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Assessment of the Vehicle's Interior Wind Noise Due to Measurement of Exterior Flow Quantities | The optimal styling of the exterior surface of a vehicle and its suspension system have a direct impact on interior wind noise. Both are determined in early project phases when no hardware prototype is available. Turbulent flows produce both external pressure fluctuations at the vehicle shell, known as hydrodynamic excitation, and sound waves, known as acoustic excitation. Hydrodynamic and acoustic sound sources are evaluated separately and relative to each other in the frequency domain in order to perform evaluations of different body shapes. The technical aim of the presented work is to investigate how acoustic quantities measured at the outside of a vehicle can be used to assess the influence of styling modifications to interior sound pressure level. The methodology is required to be capable of being integrated into the serial development process and therefore be quickly applicable. MAGNA STEYR Engineering has conducted extensive research to develop a method to ensure the best option is selected in the early project stages. |
Performance Test for Windshield Defrosting Systems for Off-Road, Self-Propelled Work Machines | This SAE Standard establishes uniform test procedures for the defrosting systems of off-road, self-propelled work machines used in construction, general purpose industrial, agricultural, and forestry machinery as referenced in table one of this document. It includes tests that can be conducted with uniform test equipment in commercially available laboratory facilities, as well as in an appropriate outdoor environment. |
Windshield with Enhanced Infrared Reflectivity Enables Packaging a Driver Monitor System in a Head-Up Display | Integration of a driver monitor system (DMS) in a head-up display (HUD) gives the monitor camera a continuous view of the driver?셲 face, since the driver always faces the road ahead. However, with both infrared (IR) illuminator and IR camera packaged in the HUD, reflectivity of the windshield is important at IR wavelengths used by the camera. Not only is windshield IR reflectivity important for a clear camera image of the driver?셲 face, but increasing windshield reflectivity also decreases the effect of ambient sunlight on the camera image of the driver?셲 face. We describe a method to measure windshield reflectivity, both for the 940 nm band used by a DMS, and for visible light for the HUD. The measurement method uses a fiber-optic spectrometer, two collimating lenses, and a method to compensate for sample tilt. The lenses are mounted on a stage that adjusts the height above the sample. As an example, this method was used to characterize an IR reflecting windshield, prepared for a prototype automotive HUD. At 940 nm, and 45째 angle of incidence, the measured reflectivity is > 85% for unpolarized incident light. For visible light at 550 nm, and 62째 angle of incidence, the measured reflectivity is 13.9% for both an IR reflecting windshield and for a reference windshield, for unpolarized incident light. The prototype windshield gives a good reflected image for the DMS IR camera and a good HUD image as seen by the driver. The method used to prepare this prototype windshield is suitable for high-volume production. |
Passenger Car Side Door Latch Systems | This SAE Recommended Practice establishes minimum performance requirements and test procedures for evaluating and testing passenger car side door latch systems. It is limited to tests that can be conducted on uniform test fixtures and equipment in commercially available laboratory test facilities. The test procedures and minimum performance requirements outlined in this document are based on currently available engineering data. It is intended that all portions of the document will be periodically reviewed and revised, as additional knowledge regarding vehicle latch performance under impact conditions is developed. |
Access Systems for Off-Road Machines | Minimum criteria are provided for steps, stairways, ladders, walkways, platforms, handrails, handholds, guardrails, and entrance openings which permit ingress to and egress from operator, inspection, maintenance or service platforms on off-road work machines parked in accordance with the manufacturer's instructions. |
Sound Measurement?봑ff-Road Self-Propelled Work Machines Operator-Work Cycle | This SAE Standard sets forth the procedures to be used in measuring sound levels and determining the time weighted sound level at the operator's station(s) of specified off-road self-propelled work machines. This document applies to the following work machines which have operator stations as specified in SAE J1116: ??Crawler Loader ??Grader ??Log Skidder ??Wheel Loader ??Crawler Tractor with Dozer ??Pipelayer ??Dumper ??Wheel Tractor with Dozer ??Trencher ??Tractor Scraper ??Backhoe ??Sweeper ??Roller/Compactor ??Hydraulic Excavator ??Pad Foot Wheel Compactor with Dozer ??Excavator and Wheel Feller-Buncher The instrumentation requirements and specific work cycles for these machines are described. The method used to calculate the time weighted average sound level at the operator station(s) is specified for Leq(5), or optional exchange rates, during continuous operation in a work cycle representing continuous medium to heavy work. The work cycles provide a repeatable reproduceable means to uniformly measure working machines against a ?쐙ard stick. A method to relate the time weighted average sound level at the operator station(s) to estimate operator sound exposure with part load work, supervision, and rest breaks is also provided. |
Integrated CAE Methods for Perceived Quality Assurance of Vehicle Outer Panels | Oil canning and initial stiffness of the automotive roofs and panels are considered to be sensitive customer ?쁯erceived quality??issues. In an effort to develop more accurate objective requirements, respective simulation methods are continuously being developed throughout automotive industries. This paper discusses a latest development on oil canning predictions using LS-DYNA짰 Implicit, including BNDOUT request, MORTAR contact option and with the stamping process involved, which resulted in excellent correlations especially when it comes to measurements at immediate locations to the feature lines of the vehicle outer panels. Furthermore, in pursuit of light-weighting vehicles with thinner roofs, a new CAE method was recently developed to simulate severe noise conditions exhibited on some of developmental properties while going through a car wash. This paper introduces such a method to discuss Fluid Structure Interaction (FSI) approach using an Arbitrary Lagrangian Eulerian (ALE) formulation in LS-DYNA짰 for vehicle roof car wash boom noise prediction. This CAE method was developed to simulate force behavior from airflow as the car wash air blowers are expelling high speed air at the vehicle roofs during car wash. LS-DYNA짰 was proven an appropriate tool to precisely simulate popping noises by creating instantaneous local instabilities - recoverable/non-recoverable - and continuous fluttering of the roof. This paper additionally briefs the history of oil canning CAE method developments from inaccurate hand push evaluation to approaches using MSC Nastran짰 to Abaqus/Standard짰, and then the final evolution to LS-DYNA짰 Implicit to provide optimized vehicle solutions. |
New Trivial Principal Component Method: System Modeling | Principal Component Analysis (PCA) is a powerful statistical technique used for understanding variation in the observed data and decomposing variation along eigenvectors, known as Principal Components (PCs), by considering variance-covariance structure of the data. Traditionally, eigenvectors that contain most of the variation or information are selected to reduce variables in data reduction. Eigenvalues of low magnitude are considered to be noise and often, not included in the dataset to accomplish dimensional reduction. Analogously, in Principal Component Regression (PCR), PCs with large eigenvalues are selected without considering correlation between the source variables and the dependent response. This inherent deficiency may lead to inferior regression modelling. While addressing this issue, an alternative to PCR is developed and proposed in this paper. In this method, a principal component associated with zero eigenvalue is termed Trivial Principal Component (TPC). This novel method involves the formulation of the TPC by including output response in the covariance matrix and then, extracting the Eigen-pairs. The TPC contains the relationship between the dependent response and the source variables and is used for extracting linear coefficients. In other words, the TPC is formulated to determine sensitivities taking into account correlation relationship between the output response and source variables. Example problems are presented to illustrate methodology and accuracy of the TPC method. Results of this method are applied on a practical production problem to make manufacturing changes for improved quality. |
Experimental Studies on Different Actuator-Sensor Configurations of Active Control Systems for the Reduction of Noise and Vibration in Vehicles | Current developments in the automotive industry such as downsizing, the use of cylinder deactivation and consistent lightweight construction increasingly enable the application of active control systems for the further reduction of noise and vibration in vehicles. In the past few years, different configurations of actuators and sensors for the realization of an active control system have been investigated and evaluated experimentally. Active engine mounts, inertial mass actuators and structural integrated actuators can be used to reduce either structural vibrations or the interior noise level. As a result, a variety of different topology concepts for the realization of an active control system arises. These can be divided into an active vibration control scenario, the direct influence of the sound field with loudspeakers or the application of structural actuators for the reduction of the interior sound pressure. In the latter case, microphones are used as error sensors for the active control system. With regard to the selection of a suitable actuator-sensor configuration special attention is required as several transfer paths for airborne and structure borne noise are existing. Furthermore, the attainable bandwidth of the applied control systems topology depends on the selection of a suitable actuator-sensor configuration and an adequate number of actuators and sensors in order to enable global control and to avoid local effects. This paper summarizes and compares different actuator-sensor configurations for the control of noise and vibration in vehicles. Beside the control performance, it highlights the electrical power requirements for the control of engine induced interior noise as a function of the selected actuator-sensor configuration. |
Development of New Test Method for Compression Load and Permanent Deformation of Weather Strip | The automotive weather strip performs functions of isolating water, dust, noise and vibration from the outside. To achieve good sealing performance, weather strip should be designed to have the high contact force and wide contact area. The compression load of weather strip is important for closing force in initial quality, but the permanent deformation is used to predict influx of wind noise over long periods of time. To check these accurately and easily, a new test method is demanded. So this paper introduces a new test method to predict the compression load and permanent deformation of 3D full vehicle by using ABAQUS. Uniaxial tension and creep tests were conducted to obtain the material data. The lab test for the permanent deformation was accelerated at high temperature during shorter time of 300 hours. Herein Proposed test method can provide accurate prediction under the different loading conditions and section shapes, and will also save time and cost. |
Ford GT Body Engineering - Delivering the Designer's Vision in 24 Months | The objective was to engineer a world-class supercar body that faithfully reproduces the 2002 Concept and pays homage to the 1960's road racer. The car had to be designed, developed and launched in 24 months, while meeting tough requirements for function, weight, occupant package and aerodynamics. Challenging features such as the cantilevered door, ?쐁lamshell??engine decklid and a deeply contoured hood were to be included. This paper will discuss how a dedicated team of enthusiasts can have a flexible approach to the engineering process, material selections and manufacturing processes to achieve the designer's vision in 24 months (Figure 1). |
Intrusion Resistance of Safety Glazing Systems for Road Vehicles | This SAE Recommended Practice specifies an intrusion resistance test method for glazing systems installed in motor vehicles. Intrusion resistance performance is determined not solely by the glazing but also by the glazing attachment to the vehicle and by the vehicle structure. Therefore, the glazing/ attachment/vehicle structure must be tested as a single unit. This test determines intrusion resistance only. The test applies to those materials that meet the requirements for use as safety glazing materials as specified in Safety Standard ANSI/SAE Z26.1 or other applicable standards. The test applies to all installation locations. |
Noise and Vibration Prediction and Validation for Off-Highway Vehicle Cab Using Hybrid FE-SEA Methodology | Operator noise is an important aspect for noise and vibration of off-highway vehicles and a quieter cab is critical for the operator comfort. The noise level inside the cab is influenced by structural and acoustic transfer paths. In this paper, we used hybrid FE-SEA approach to consider both structural and acoustic transfer path as FEM and SEA methods individually face limitations in high and low frequencies respectively. A hybrid FE-SEA cab model was built to predict the structural and acoustic transfer functions. The analysis model was built with the systematic approach validated at each step with the laboratory test results. For the structural transfer function, structural excitations were applied at four cab mount locations and accelerations at various locations on the cab were validated. For the acoustic transfer function, the cab was excited with the volume velocity source inside the cab and sound power output of various panels were calculated and compared to the test results. Good agreement was observed between the simulation and the test results for both structural transfer path and acoustic transfer path. |
Measurement and Presentation of Truck Ride Vibrations | There are two ways to assess the characteristics of ride vibrations of a vehicle during its operation. Subjective evaluation and objective measurement. Subjective assessments of the ride vibrations experienced by drivers during ride evaluations are generally performed by a panel of drivers and/or passengers who are instructed to operate or ride a group of vehicles in a predetermined manner in order to subjectively assess the levels and characteristics of ride vibrations. Figures 6A through 6C show examples of subjective evaluation forms presently in use. The disadvantages of the subjective method include need for careful experimental design, need for statistically unbiased samples, complexity of human perceptions of vibrations, and difficulty in comparing qualitative data of vehicles evaluated at different times and/or by different groups of people. Often ride characterization is not an easy task using only qualitative or descriptive terms. Therefore, it is necessary and desirable to develop objective techniques to enable ride engineers and others to measure ride vibrations during ride assessment in a quantitative manner. This recommendation details a uniform method for the measurement of ride vibrations of all Class 7 and 8 commercial vehicles, including both combination vehicles and straight trucks. Vibrations are to be measured utilizing cab and seat-pad mounted accelerometers in vertical (z axis) and fore/aft (x axis) directions. The measurement in lateral direction (y axis) is optional as these vibrations from a ride assessment standpoint are seldom significant in commercial vehicles. Several currently utilized methods of displaying, analyzing, and combining the measured accelerations are presented. This recommendation does not make any statements concerning how well any of the objective ride measures will correlate to subjective evaluations of ride, nor does it deal with any limits or establish any desirable values for acceptable ride. It is recognized that objective ride evaluation methods have some disadvantages due to the complexities of these measures, sophistication of instrumentation and analysis techniques, etc. Therefore, it is recommended that technically trained personnel conduct the objective tests and analyze the data. |
A Strategy for Developing an Inclusive Load Case for Verification of Squeak and Rattle Noises in the Car Cabin | Squeak and rattle (S&R) are nonstationary annoying and unwanted noises in the car cabin that result in considerable warranty costs for car manufacturers. Introduction of cars with remarkably lower background noises and the recent emphasis on electrification and autonomous driving further stress the need for producing squeak- and rattle-free cars. Automotive manufacturers use several road disturbances for physical evaluation and verification of S&R. The excitation signals collected from these road profiles are also employed in subsystem shaker rigs and virtual simulations that are gradually replacing physical complete vehicle test and verification. Considering the need for a shorter lead time and the introduction of optimisation loops, it is necessary to have efficient and inclusive excitation load cases for robust S&R evaluation. In this study, a method is proposed to truncate and identify the important parts of the different road profiles that are often used for S&R physical verification and then merge them to develop one representative excitation load case. The criteria for signal truncation were based on the S&R risk and severity metrics calculated from the vibration response at the critical interfaces for S&R. the method was used in a case study involving the instrument panel of a passenger car. Results of the virtual simulation and the rig tests were compared with the complete vehicle test. The proposed synthesised signal generation strategy was validated by physical testing through measuring vibration signals. The results supported the possibility of replacing multiple S&R excitation signals with one single representative inclusive signal, while the quality of S&R risk prediction from the system response was maintained. The outcome of this work can lead to a more efficient physical and virtual S&R verification in the development process of passenger cars. |
Coupled-SEA Application to Full Vehicle with Numerical Turbulent Model Excitation for Wind Noise Improvement | Wind noise is becoming a higher priority in the automotive industry. Several past studies investigated whether Statistical Energy Analysis (SEA) can be utilized to predict wind noise. Because wind noise analysis requires both radiation and transmission modeling in a wide frequency band, turbulent-structure-acoustic-coupled-SEA is being used. Past research investigated coupled-SEA?셲 benefit, but the model is usually simplified to enable easier consideration on the input side. However, the vehicle is composed of multiple interior parts and possible interior countermeasure consideration is needed. To enable this, at first, a more detailed coupled-SEA model is built from the acoustic-SEA model which has a larger number of degrees of freedom for the interior side. Then, the model is modified to account for sound radiation effects induced by turbulent and acoustic pressure. Another concern about utilizing the coupled-SEA to wind noise development is the estimation of the turbulent and acoustic input. Several options are available for identifying the input, such as on-road data measurement, CFD simulation, and numerical turbulent model estimation. Because the turbulent model can be helpful to consider the countermeasure direction, the turbulent model application to coupled-SEA is considered. However, an appropriate turbulent model is still unclear whereas there are many kinds of turbulent models proposed. Due to this, as the next step, this paper performs a validation study in a wind tunnel to identify the suitable turbulent model for the wind noise simulation. Lastly, the entire method is validated with on-road measurements. A detailed coupled-SEA model under appropriate turbulent model input simulates test case conditions and its prediction accuracy is discussed along with a wind noise. |
Prediction and Validation of Cab Noise in Agricultural Equipment | To improve overall customer experience, it is imperative to minimize the noise levels inside agricultural equipment cab. Up-front prediction of acoustic performance in product development is critical to implement the noise control strategies optimally. This paper discusses the methodology used for virtual modeling of a cab on agricultural equipment for prediction of interior noise. The Statistical Energy Analysis (SEA) approach is suitable to predict high frequency interior noise and sound quality parameters such as articulation index and loudness. The cab SEA model is developed using a commercial software. The structural and acoustic excitations are measured through physical testing in various operating conditions. The interior noise levels predicted by the virtual model are compared with the operator ear noise levels measured in the test unit. The resultant SPL spectrum from SEA correlates well with the test. This model is used to optimize the noise control treatments and improve the NVH performance of the cab. |
Theoretic Analysis of Factor to Affect Door Closing Force by Positioning Error of Assembly Fixture | In order to analyze positioning errors of assembly fixture of car SANTANA 2000, a 3D CAD model of fixture is built in this paper. Six typical deviation models are defined on the basis of six points positioning principle for fixture. The assembly gap distribution between door and side frame is analyzed and the influence of different deviation patterns on assembly gap is studied, and the effect of assembly gaps on door closing force is evaluated meanwhile. The results show that positioning errors of door assembly fixture is one of the most important factors to affect the door closing force. |
The Development of Testing Device for Compression Deformation of Automotive Door Weather-strip Seals | Automotive door system weather-strip seals play a major role in determining door closing effort, isolating the passenger compartment from water and reducing the wind noise inside the vehicle. They are typically dual extrusion bulbs of sponge and dense rubber. The bulbs can be round, triangular or free form in shape with a height of approximately 15-30 mm. The special properties of dense and sponge rubber material are (1) High extensibility. (2) Low extensional and shear modulus. Dense rubbers are nearly incompressible. Sponge rubbers are, on the other hand, very compressible. (3) Nonlinear force vs. extension behavior. Because of the above-mentioned factors, the deformation of the automotive door weather-strip seal during the compression is very complicated. A testing set has been developed for obtaining compression deformation of the door weather-strip by using stereovision theory. Precision instruments of optical grating and force sensor are also integrated in this set. Force-displacement response characteristics of compression at varied speed can be controlled. This work will lay solid foundations for characteristic and structure as well as optimization design of the automotive weather-strip. |
The Effects of Unsteady On-Road Flow Conditions on Cabin Noise: Spectral and Geometric Dependence | The in-cabin sound pressure level response of a vehicle in yawed wind conditions can differ significantly between the smooth flow conditions of the aeroacoustic wind tunnel and the higher turbulence, transient flow conditions experienced on the road. Previous research has shown that under low turbulence conditions there is close agreement between the variation with yaw of in-cabin sound pressure level on the road and in the wind tunnel. However, under transient conditions, sound pressure levels on the road were found to show a smaller increase due to yaw than predicted by the wind tunnel, specifically near the leeward sideglass region. The research presented here investigates the links between transient flow and aeroacoustics. The effect of small geometry changes upon the aeroacoustic response of the vehicle has been investigated. It was found that sideglass pressures showed close agreement at all turbulence levels while surface sound pressure levels also showed similar behaviour under a wide range of on-road flow conditions. While the overall sideglass sound pressure level changed under the various yaw conditions, the change in shape of the frequency spectrum was less significant. Geometry changes made to a base vehicle reduced the sensitivity of the in-cabin noise to on-road turbulence, showing that shape-change can modify sensitivity to on-road turbulence. |
NVH Challenges for Low Cost and Light Weight Small Cars | In worldwide automotive markets, the migration of customers towards smaller cars having compact, fuel-efficient design is well established and accepted as an engineering challenge by global automotive OEMs. Tata Motors of India has established a precedent by developing an ultra low cost and light weight car (the Nano), and has thereby created a new market segment for such cars that are more affordable to most of the population. This is now becoming established as a brand of low cost, safe transport in both rural and urban market segments. Despite the market moving towards such compact, fuel-efficient designs, customers are unwilling to lose many of the vehicle attributes to which they have been accustomed in previous types of entry-level cars. Addressing this marketing requirement places some significant challenges before the designers of this type of car. This paper considers some of the fundamental technical challenges faced in delivering acceptable NVH performance in a light weight, low cost car. One of the most significant issues is the use of engines with lower cylinder counts than conventional cars, leading to strong impulsiveness and lower firing frequencies. These can become problematic when mounted in vehicle structures that have a high interior volume in proportion to their mass and are often not able to meet established norms for benchmark vibro-acoustic performance. Other matters considered include the high ratio of power train mass to total vehicle mass and the higher ratio of laden to un-laden mass. Such vehicles are also generally intended for manufacture by lower skilled workers in regions with little or no automotive assembly heritage, so they must be designed for ease of ?쐒ight first time??assembly. Using the example of this product, some of the possible solutions to these challenges faced by the NVH team are examined. The paper will show that it is feasible to deliver market-acceptable NVH behavior despite the strong constraints inherent in such types of vehicle, by means of lean and innovative design. |
Experimental Method Extracting Dominant Acoustic Mode Shapes for Automotive Interior Acoustic Field Coupled with the Body Structure | For a numerical model of vibro-acoustic coupling analysis, such as a vehicle noise and vibration, both structural and acoustical dynamic characteristics are necessary to replicate the physical phenomenon. The accuracy of the analysis is not enough for substituting a prototype phase with a digital phase in the product development phases. One of the reasons is the difficulty of addressing the interior acoustical characteristics due to the complexity of the acoustical transfer paths, which are a duct and a small hole of trim parts in a vehicle. Those complex features affect on the nodal locations and the body coupling surface of acoustic mode shapes. In order to improve the accuracy of the analysis, the physical mechanisms of those features need to be extracted from experimental testing. The accuracy of the vibro-acoustic coupled system model for the low frequency range depends on how accurately modal characteristics are represented at the input, output, and the structure-acoustic coupling surface. Therefore, this study focus on extracting the detailed acoustic mode shapes on the coupling surface for the improvement of the model accuracy. The non-linear least square method as the one utilized in the previous study was applied to the new test data sets of an actual vehicle. In the previous study, it had one remaining issue, which was how to extract acoustic mode shapes in the frequency range of higher damping and higher acoustic modal densities. In order to solve this issue, the number of acoustic excitation was increased considering acoustic mode shapes. The eight loudspeakers were utilized as an acoustical excitation to excite acoustic modes evenly in the acoustic interior dimensions for higher frequency. With the results of this testing, the acoustic modes of an actual vehicle with heavy damping were accurately extracted as the complex mode shapes of no phase lag between nodes, which looks similar the un-coupled normal modes without rotation in animation up to 200Hz. The synthesized FRFs were replicated well with only the extracted several dominant acoustic mode shapes. |
Body Induced Boom Noise Control by Hybrid Integrated Approach for a Passenger Car | Vehicle incab booming perception, a low frequency response of the structure to the various excitations presents a challenging task for the NVH engineers. The excitation to the structure causing boom can either be power train induced, depending upon the number of cylinders or the road inputs, while transfer paths for the excitation is mainly through the power train mounts or the suspension attachments to the body. The body responds to those input excitations by virtue of the dynamic behavior mainly governed by its modal characteristics. This paper explains in detail an integrated approach, of both experimental and numerical techniques devised to investigate the mechanism for boom noise generation. It is therefore important, to understand the modal behavior of the structure. The modal characteristics from the structural modal test enable to locate the natural frequencies and mode shapes of the body, which are likely to get excited due to the operating excitations. The critical transfer paths for the excitation through the structure have been identified with the help of transfer path analysis, while running mode analysis indicate the dynamic behavior of the structure due to the excitation. Similarly, the acoustic modal analysis describes the fundamental acoustic modal characteristics of the cabin cavity. The introduction of the experimental running mode inputs of the structure to the acoustic finite element model makes the hybrid analysis possible. The panel contribution analysis focuses on the components that have the significant contribution in the booming noise for in-phase as well as out of phase panels. The modifications revealed from the systematic study by hybrid approach, has led to substantial reduction in the booming noise both objectively and subjectively. This paper also describes the improvements suggested to reduce the boom noise. |
High-Frequency Time Domain Source Path Contribution: From Engine Test Bench Data to Cabin Interior Sounds | This work presents an application of airborne source path contribution analysis with emphasis on prediction of wideband sounds inside a cabin from measurements made around a stand-alone engine. The heart of the method is a time domain source path receiver technique wherein the engine surface is modeled as a number of source points. Nearfield microphone measurements and transfer functions are used to quantify the source strengths at these points. This acoustic engine model is then used in combination with source-to-receiver transfer functions to calculate sound levels at other positions, such as at the driver's ear position. When combining all the data, the in-cabin engine sound can be synthesized even before the engine is physically installed into the vehicle. The method has been validated using a powertrain structure artificially excited by several shakers playing band-limited noise so as to produce a complicated vibration pattern on the surface. First the excited structure is studied alone; next a vehicle cabin was lowered onto the structure without touching. As a result we can compare the combination of using only in-vehicle operating/transfer data or using powertrain only operating data and in-vehicle transfer data for synthesizing interior sounds. Very good agreement between the two procedures was obtained and comparable to the actual sound measured inside the cabin during operation. In addition to verifying the above procedure, the same near-field microphone setup, whether powertrain alone or with cab on top, can be used to assess the radiated sound power from the vibrating structure. The procedure is outlined and the obtained sound power spectra are validated against a standardized hemisphere sound power measurement showing very good agreement in general. |
Further Development of the PNCA: New Panel Noise Contribution Reference-Related (PNCAR) | The Panel Noise Contribution Analysis (PNCA) is a well-known methodology for an airborne Transfer Path Analysis (TPA) in car interior. Pressure contribution from the individual panels at a reference point can be very accurately calculated. Acoustic Trim package treatment can therefore be optimized in terms of frequency and panel area which saves money and time. The method uses only one type of sensors so called particle velocity probes for measuring source strength as well as transfer function (with a reciprocal measurement). Traditionally the PNCA makes use of a big amount of probes at fixed points (about 50) hence non-stationary conditions can be measured as well. Typically the measurement is performed in 3 sessions resulting in 150 individual panels. Because of the low spatial resolution the method can only be used at mid-low frequency range. The new Panel Noise Contribution Analysis Referenced (PNCAR) implements a new post-processing technique which uses a reference sensor in order to extract the relative phase information for the individual panel and frequency of interest. This technique makes it possible to use a limited amount of probes for measuring a whole car interior. Typically 11 probes are used in 11 sessions. Consequently, the methodology becomes more robust and commercially more affordable than conventional PNCA. A real measurement in driving condition was done on the highway in order to validate the methodology. Two different approaches to apply the theory derivations are compared and discussed. |
The influence of A-pillar obscuration/location on driver visibility | During the early phase of vehicle development, one of the key design attributes to consider is visibility for the driver. Visibility is the ability to see one?셲 surrounding environment while they are driving. Therefore, it is one of the key requirements to be considered during the vehicle design. Certain vehicle characteristics such as the size of windshield and the design of the pillars influence the perception of visibility for the driver. One specific characteristic influencing satisfaction is A-pillar obscuration and location, which is the subject of this paper. The objective of this project is to analyze the relationship between the A-pillar obscuration/location with the driver satisfaction under real world driving conditions, based on research, statistical data analysis and dynamic clinics. Other influences, such as the position of the occupant in the seat was also studied and captured in this paper. |
Vehicle Passenger Door Hinge Systems | The scope of this SAE Recommended Practice is to establish recommended uniform test procedures and minimum static load requirements for vehicle passenger door hinge systems. Tests are described that can be conducted on test fixtures and equipment in laboratory test facilities. The test procedures and minimum performance requirements outlined in this document are based on currently available engineering data. It is intended that all portions of the document be periodically reviewed and revised as additional knowledge regarding vehicle hinge system performance under impact conditions is developed. |
3D Simulation Methodology to Predict Passenger Thermal Comfort Inside a Cabin | The vehicle Heating, Ventilation and Air conditioning (HVAC) system is designed to meet both the safety and thermal comfort requirements of the passengers inside the cabin. The thermal comfort requirement, however, is highly subjective and is usually met objectively by carrying out time dependent mapping of parameters like the velocity and temperature at various in-cabin locations. These target parameters are simulated for the vehicle interior for a case of hot soaking and its subsequent cool-down to test the efficacy of the AC system. Typically, AC performance is judged by air temperature at passenger locations, thermal comfort estimation along with time to reach comfortable condition for human. Simulating long transient vehicle cabin for thermal comfort evaluation is computationally expensive and involves complex cabin material modelling. Lattice-Boltzman (LBM) based PowerFLOW solver coupled with Finite element based PowerTHERM solver is employed in this study to simulate long transient soak and Cooldown along with thermal comfort. Additionally, the human thermal physiology is modeled, to account for subjective evaluation of the in-cabin thermal environment. Berkeley comfort model library is available in PowerTHERM. The model takes care of the vasodilation and vasoconstriction effects, based on the external human ambient, along with the effects of clothing and the passenger metabolic rate. Vasodilation and vasoconstriction regulate the blood flow by widening or narrowing the blood vessels depending upon the warm or cold ambient conditions. LBM based flow solver is used to predict convective heat transfer phenomenon for both the exterior and interior of the cabin. The conduction and the radiation effects including the solar loading were solved using PowerTHERM. Physical test is conducted under controlled ambient conditions of climate chamber for a car cabin. Results from the coupled approach correlates well the test results for both hot soaked and cool-down conditions with a significant reduction in simulation time. During the cabin cool-down phase, passenger thermal comfort is predicted using Predictive Mean Vote. This process is further used to study the effect of change in properties of the glazing surfaces for predicting cabin thermal environment like heat ingress and cabin surface and air temperatures. Thermal comfort is also predicted and compared with baseline design. Glazing material sensitivity is carried out for absorbing and reflective glass material and its impact on cabin surface and air temperature and thermal comfort is predicted here. This process is deployed and found useful for predicting vehicle level thermal comfort. |
Systematic CAE Approach to Minimize Squeak Issues in a Vehicle Using Stick-Slip Test Parameters | Due to recent advancements in interior noise level and the excessive use of different grade leathers and plastics in automotive interiors, squeak noise is one of the top customer complaints. Squeak is caused by friction induced vibration due to material incompatibility. To improve costumer perception, interior designs are following zero gap philosophy with little control on tolerances leading to squeak issues. Often manufacturers are left with costly passive treatments like coatings and felts. The best option is to select a compatible material with color and finish; however, this will reduce the design freedom. Material compatibility or stick-slip behavior can be analyzed with a tribology test stand. However, this test is performed on a specimen rather than actual geometry. There were instances, when a material pair was found incompatible when tested on a specimen, but never showed any issue in actual part and vice versa. Thus, interface stiffness and system sensitivity between the parts are important while analyzing the stick-slip behavior before implementing any solutions. To improve the process vehicle interiors are analyzed by CAE methods to evaluate stick-slip behavior by utilizing SSP test data. The CAE methodology considers wide range of input load cases, global and local system sensitivity, local geometries, and connection stiffness to get realistic results from squeak simulations, which otherwise not possible with stick-slip testing. In the present study, ?쐍o relative movement no squeak??philosophy is used to drive the design of interior trims to avoid squeaks. Squeak risk at interface is evaluated by comparing in-plane relative displacement with ??/ IRmax??value obtained from stick-slip testing. Meaningful information has been extracted through linear static analysis to understand the influence of preloading on contact forces between the interfaces. This approach has improved the squeak prevention process in product development without changing materials or usage of passive treatments. |
Truck Front Cabin Mount Tuning for Cabin Noise Boom, Overall Interior Noise and Vibration Reduction | In today?셲 automobile industry refined NVH performance is a key feature and of high importance governing occupant comfort and overall quality impression of vehicle. In this paper interior noise and vibration measurement is done on one of the light truck and few dominant low frequency noise booms were observed in operation range. Modal analysis was done for the cabin at virtual as well as experimental level and few modes were found close to these noise booms. Vibrations were measured across the cabin mounts and it was found that the isolation of front mounts is not effective at lower frequencies. Taking this as an input, the mount design was modified to shift the natural frequency and hence improve the isolation behavior at the lowest dominant frequency. This was followed by static and dynamic measurement of the mounts at test rig level to characterize the dynamic performance and stiffness conclusion. Finally the interior noise and vibration measurement is carried out on truck fitted with selected mounts and substantial vibration, overall noise reduction and drastic boom noise reduction was achieved. This paper takes up a real-time noise scenario, its root cause analysis and establishment of final solution for same. It covers various activities like noise, vibration measurement and analysis, virtual and experimental modal evaluation, mount transmissibility evaluation followed by design and tuning for corrects stiffness, and finally verification at rig and vehicle level. Hence this works runs through complete flow of NVH development cycle. The cabin mount design patent registration is approved. |
Electromagnetic Analysis of Permanent Magnet Brushed DC Motor for Automotive Applications?봒art 1 | Permanent magnet brushed DC (PMBDC) motors are mostly preferred in many automotive applications because of better power density and easier control. Five different automotive applications such as electric parking brake (EPB), power seat, power window, sunroof drive, and tire air pump are chosen and discussed in this paper. A step-by-step electromagnetic analysis is carried out for all the designed models. Low-cost ferrite-based magnets are used for cost reduction keeping the efficiency as high above 77% in all the models. Comparison on performance and cost are discussed in the conclusion section. |
Reinforcement of Low-Frequency Sound by Using a Panel Speaker Attached to the Roof Panel of a Passenger Car | The woofer in a car should be large to cover the low frequencies, so it is heavy and needs an ample space to be installed in a passenger car. The geometry of the woofer should conform to the limited available space and layout in general. In many cases, the passengers feel that the low-frequency contents are not satisfactory although the speaker specification covers the low frequencies. In this work, a thin panel is installed between the roof liner and the roof panel, and it is used as the woofer. The vibration field is controlled by many small actuators to create the speaker and baffle zones to avoid the sound distortion due to the modal interaction. The generation of speaker and baffle zones follows the inverse vibro-acoustic rendering technique. In the actual implementation, a thin acrylic plate of 0.53x0.2 m2 is used as the radiator panel, and the control actuator array is composed of 16 moving-coil actuators. The shape of the desired speaker zone is an ellipse, and the required amplitude of this piston source is pre-calculated to satisfy the desired sound radiation at the ear position. The gain of the actuator array to properly generate the desired vibration field is obtained by solving an inverse problem constructed by the transfer mobility between each actuator and field point on the plate. For the recruitment of the low-frequency deficiency of human auditory characteristics, the desired sound spectrum is set to follow the equal-loudness contour of 40 phons. It is confirmed that the woofer in a car can be replaced by the developed panel speaker. |
Linear Impact Procedure for Occupant Ejection Protection | The objective of this document is to enhance the test procedure that is used for ejection mitigation testing per the NHTSA guidelines as mentioned in the FMVSS226 Final Rule document (NHTSA Docket No. NHTSA-2011-0004). The countermeasure for occupant ejection testing is to be tested with an 18kg mass on a guided linear impactor using the featureless headform specifically designed for ejection mitigation testing. SAE does not endorse any particular countermeasure for ejection mitigation testing. However, the document reflects guidelines that should be followed to maintain consistency in the test results. Examples of currently used countermeasures include the Inflatable Curtain airbags and Laminated Glass. The testing procedure is as follows: 1 Determine the daylight opening 2 Identify target locations per the FMVSS226 Final Rule 짠5.2 a Target locations for all windows and daylight openings b Perform the target elimination process c Reconstitute the targets 3 Determine the zero-plane 4 In case of advanced glazing, determine if the glazing has to be part of the test and pre-brake it at a 75mm offset a If yes, than follow the procedure for pre-breaking the laminated glazing 5 Run the test a At 5.6m/s with a 1.5s delay b At 4.4m/s with a 6.0s delay |
Buffeting Noise Characteristics and Control of Automobile Side Window | The computational fluid dynamics (CFD) software STAR-CCM+, Large Eddy Simulation (LES) method, and the Dynamic Smagorinsky-Lilly sub-lattice Model (DSLM) are used to study the buffeting noise characteristics of automobile side windows. Buffeting noise control methods are studied, and a comparison with experimental data verified the correctness of the simulation. Results show that periodic vortexing of the window opening area causes the strong pressure pulsation in the passenger compartment, and the combined effect of two mechanisms, namely, acoustic feedback and Helmholtz resonance, generates the buffeting noise. The sound pressure level (SPL) of buffeting noise produced by opening only the front window is lower than that of the rear window; Adding a rear mirror convex structure and a rain baffle structure reduces the buffeting noise SPL of the front window by 4.5 dB and 7.8 dB, respectively; Adding a convex structure and a non-smooth structure in the B pillar reduces the buffeting noise SPL of the rear window by 3.8 dB and 2.2 dB, respectively. |
Analyzing Effects of Upperbody on Road Noise of Platform-Sharing Vehicles | Platform sharing is widely used for reducing time and cost of vehicle development. It has been believed that vehicles that employ the same platform show similar performances of noise and vibration. Recently, however, it is observed that two vehicles that share the same platform present a noticeable difference in road noise. The structural difference between the two vehicles is located only at the upperbody of a Body In White (BIW). In order to investigate the effects of the upperbody on the road noise, several analyses such as (1) input point stiffness, (2) noise transfer function (NTF), and (3) road noise are performed using finite element (FE) models of the vehicles. As a result, it is found that the upperbody affects the NTF of the trimmed body and the road noise, which explains the dissimilarity of the road noise for the two vehicles. A novel method based on equivalent radiated power (ERP) is proposed to assess the upperbody. It is shown that analysis results obtained using the method show good correlation to the NTF of the trimmed body, which determines the road noise. Thus the proposed method can be used to assess an upperbody and predict the road noise of platform-sharing vehicles in the early stage of vehicle development. |
An Aspect of Noise Vibration and Harshness Issues in Electric Vehicles | Electric vehicles (EVs) are gaining ground more recently. New powertrains like electric and hybrid come with new noise, vibration, and harshness (NVH) issues previously unknown. A new approach to acoustic engineering is required to study NVH issues in EVs. The two primary dominant sources in an internal combustion engine (ICE) are engine noise due to combustion, and exhaust noise would not be there for EVs. EVs are less noisy, but several motor or battery cooling noises are encountered during design and validation. NVH is an indispensable part of subsystem integration in the EV powertrain. This article deals with various noise issues generally observed in EVs and their possible treatment to achieve the comfort car, satisfying customer expectations. The NVH-related problems for EVs are categorized into five categories: motor, wind, road, auxiliary, and other noises like integration. A detailed study of each category/problem type and NVH-suppression methods are discussed. The selection of powertrain mount architecture and its impact on load transfer and crash performance are also presented in this article. A balancing approach is required for NVH, durability, and crash requirements. |
Acoustical Materials: Solving the Challenge of Vehicle Noise | For a limited time only, SAE is offering a 20% discount off the list price of $70. Purchase today for $56. What is acoustics? What is noise? How is sound measured? How can the vehicle noise be reduced using sound package treatments? Pranab Saha answers these and more in Acoustical Materials. Acoustics is the science of sound, including its generation, propagation, and effect. Although the propulsion sources of internal combustion engine (ICE) vehicles and electric motor-powered vehicles (EV) are different and therefore their propulsion noises are different, both types of vehicles have shared noise concerns: Tire and road noise Wind noise Vehicle noise and vibration issues have been there almost from the inception of vehicle manufacturing. The noise problem in a vehicle is very severe and is difficult to solve only by modifying the sources of noise and vibration. Sound package treatments address the noise and vibration issues along the path to reduce in-cabin noise. In Acoustical Materials, readers will grasp the science of reducing sound and vibration using sound absorbers, sound barriers, and vibration dampers. Sound provides information on the proper operation of the vehicle, but if unchecked, can detract from the consumer experience within the vehicle and create noise pollution outside the vehicle. Acoustical Materials provides essential information on the basics of sound, vehicle noise source, how these are measured, how vehicle owners perceive sound, and ultimately, how to solve noise problems in vehicles using sound package materials. |
Influence of Inner Panel Structure in Overall Liftgate Performance | Prevailing global industry has set an environment that fosters the search for new procedures, technology and/or knowledge that allows time reduction in vehicle development and, at the same time, to offer the best strength and reliability characteristics to the customers. Constant improvement mindset is applied to those systems that yield the highest interaction with the final user, among those, it is paramount to take notice of systems like the vehicle closures (such as liftgates, hood, doors, etc.). In automotive industry, the efforts to comply with high standards are often focused to incorporate new materials, which are resistant and lightweight, on the other hand, this project explores the liftgate behavior from a more fundamental standpoint, which is the geometry and how it is related to the requirements that the liftgate should comply with. In this article, a research was conducted to establish which components have a high influence in the structural integrity of the liftgate, using as a starting point the structural testing?셲 that are performed to sign off the closures design during the product development stage. Furthermore, a comparison analysis between different liftgate structures, stand out the geometric design patterns of the interior panel of the liftgate that is present in the hatchback and sport utility vehicles. Finally, this project includes optimization proposals that determined the inner panel geometric form that enables the liftgate to comply with the structural requirements and comparison of the liftgate assessments results between the commonly used profiles across the industry. |
The 747-400 Dreamlifter - Swing Tail Door Alignment and Latch Mechanism | One essential feature of the 787 production system is the 747-400 Large Cargo Freighter (LCF), also known as the Dreamlifter,[1] and its ability to quickly and efficiently transport large components from global manufacturing locations to the final assembly site in Everett, Washington. This unique airplane has a tail section (Swing Tail) that opens to allow cargo loading. Quickly loading and unloading cargo is largely dependent on the reliable operation of the integral swing tail door alignment and latching systems. The swing tail door is approximately 23 feet horizontally by 29 feet vertically in size. The alignment and latching systems are required to function in a wide range of environmental conditions including temperature extremes and high winds. At the same time, these systems must ensure that flight loads are safely transmitted from the tail to the airplane fuselage without inducing undue fuselage preloads and without excessive play in the latching system. These requirements presented a developmental challenge that called for an innovative solution for adjustment of the latching and alignment mechanisms. |
Evaluating Self-Unlocking Doors in Rollover Accidents using a Shock Testing Machine | Automotive manufacturers often rely upon features such as automatic locking to enhance the security and crashworthiness of doors in rollover accidents. This can be verified in warnings conveyed to vehicle owners through some owner's manuals. At the present time, there are no requirements on the dynamic performance of door locking systems within the Federal Motor Vehicle Safety Standards (FMVSS), although some static inertia requirements exist for latch systems. Field accident investigation and laboratory testing has revealed that some locked doors can self-unlock in rollover accidents when a vehicle sustains a roof impact. Using standard laboratory shock testing machinery, the acceleration boundaries required to trigger self-unlocking have been mapped for some sample doors. Impact pulses of surprisingly low levels of acceleration, when combined with sufficient duration have been found to trigger this response. Furthermore, two entirely different failure mechanisms have been identified and documented thus far. One failure mode results directly from inertial triggering of the locking system; this mode is anticipated by FMVSS. The second failure mode is the unexpected consequence of the vibratory response of the lock system linkage. This failure mode has not yet been recognized in the safety literature. This paper presents the findings of a field accident investigation where self-unlocking was believed to have occurred as well as test data from doors exhibiting the two different self-unlocking mechanisms. |
Investigation of Crash Impact Induced Oscillatory Response of Elements of Automotive Latch Systems | Vehicle door closure systems often include self-balancing double pendulum mechanisms. For example, the counterweight in the outside handle assembly is used to reduce handle motion under inertia loadings occurring during crash events. The system is configured in such a way that the inertia forces developed during a crash are applying opposite moments to each of the pendulums (i.e., to the handle and the counterweight). Investigation of crash impact induced oscillatory response of such mechanisms is presented in this paper. A comprehensive dynamic model is developed that captures all essential characteristics of the double pendulum mechanism. An important aspect of the model is its discontinuous nature due to potential impacts between both pendulums and between one of the pendulums and the base part. Analytical conditions of self-balancing of the double pendulum system are formulated and used to provide an insight into the principles of self balancing. During dynamic simulations of the system, high frequency / high acceleration amplitude oscillatory motion of the base part provides inertia input to the system. It is shown that the double pendulum systems usually respond to such excitation with irregular motion. A methodology has been developed to study this system behavior and to analyze the resulting motion of the system. The multi-level analysis presented in the paper is used to investigate the conditions under which the system may not respond to external excitations, and to quantify the irregular response of the system when it does. The sensitivity of the solutions of the dynamic model to variation of system parameters and input characteristics is also addressed in the paper. |
Testing and Modeling of Elevator Door Retention During Hallway Applied Lateral Loads | Most do not consider there to be a risk in pushing on, bumping into or falling against an elevator door from the hallway side. However, the lack of the elevator cars presence alone, and the potential for severe injury or even death make this seemingly mundane situation potentially critical. Standards exist relative to such situations, and past and current designs attempt to account for this possibility, still people get injured interacting with these doors every year. In order to evaluate a real-world elevator door system's ability to withstand the quasi-static and impactive loads that can be placed on it by the general public during its life, both intentionally and unintentionally, a predictive tool is needed. This work represents the combination of empirical laboratory testing and numerical modeling of a typical elevator door system exposed to quasi-static and dynamic loading. The test procedures and methodology employed in this work provided repeatable and reliable results in quasi-static and dynamic testing. Numerical simulation using MADYMO established a robust and accurate quasi-static model of a primary door failure mode. The quasi-static MADYMO model can be used for quasi-static loading at any height of load application on the door and at any gib engagement depth up to full engagement with reliable and repeatable results. The dynamic MADYMO model showed accuracy at the 3 mm (0.12 in.) gib engagement depth at any contact height and any contact speed. A preliminary 6 mm (0.24 in.) gib engagement depth dynamic model has been verified for full-mass impacts of up to 1.5 m/s (4.8 ft/s). |
DRE NVH Contribution Analysis of Vehicle Cavity Fillers - NVH Target Setting Process | The goal of this study is to measure the Noise, Vibration and Harshness (NVH) performance of passenger vehicle cavities under different drive conditions. Until now, little attention has been given to the impact of NVH performance of cavity fillers with respect to the driver's perception. To further understand this phenomenon, a four door sedan was instrumented with several microphones placed within different vehicle cavities. After instrumentation, the vehicle was tested under various road conditions; cruise, idle, street run, rough road and wide open throttle. The resulting data shows that there is a substantial noise presence in the hinge pillar and lower rocker cavities for all test conditions. The data also provides a means to rank the importance of the sound contribution of each vehicle cavities with respect to other cavities. To understand the NVH contribution of individual cavities to the driver's perception, the vehicle was placed inside a semi-anechoic chamber. The goal was to compute the transfer function of each cavity with respect to the driver's ear (DRE). The individual transfer functions could have been calculated by placing the random noise generator within each cavity while measuring the response at the DRE. This technique would have required several iterations of moving the noise generator from cavity to cavity. However, using the reciprocity concept, the noise generator can be placed at the DRE and the responses at all cavities can be measured simultaneously. Finally, having the road data along with all transfer functions, the relative importance of each cavity was determined with respect to the driver's ear. This methodology would enable vehicle manufacturers to understand the importance of cavity fillers to the vehicle's overall NVH performance. This technique would also help to optimize the application and provides NVH target setting goals for the vehicle cavity fillers. |
Numerical Investigation of the Transmission Loss of Seals and Slits for Airborne SEA Predictions | Seals and slits are often an important transmission path for vehicle interior noise at mid and high frequencies, and they are therefore often included in system level SEA models of interior noise. The transmission loss of seals and slits in such models is typically either measured experimentally or predicted using simple analytical models. The problem with the former is that it is expensive to investigate different design options using test; the problem with the latter is that simple analytical models often do not contain enough detail. The objective of this paper is therefore to investigate how much detail is needed in order to predict the transmission loss of typical slits and seals. Typical door seals are not directly exposed to exterior and interior sound fields, but instead are inserted in complicated ?쐁hannel??sections formed by the door and pillar or rail structures. This study is therefore divided in two parts. The first part focuses on the effect of the channel (a ?쐓lit??type aperture between two acoustic spaces). The acoustic performance of various slits is investigated using fast 3D numerical models based on the Hybrid FE-SEA method. The use of this method makes it possible to diagnose the parameters controlling the transmission loss of a slit or seal across a broader frequency range than is possible with standard numerical methods such as BEM. The second part of the paper focuses on the transmission loss of the seal itself (with and without the presence of the channel). The sensitivity of the transmission loss to the deformation of the seal is also investigated (the deformation of the seal is predicted using a full non-linear deformation/contact analysis). |
Practical Application of Six Sigma with a Focus on Transmitted Variation ??A Door Check Arm Opening Effort Case Study | This paper presents an approach for Six Sigma strategies to reduce the occurrence of failure mechanisms. In general terms, there are two ways to reduce the failures: a) shifting or tuning - DMAIC approach or b) shrinking - DCOV approach. When shifting or tuning, we move the mean output away from the failure mode boundary and when shrinking, we reduce the variability of the output. Also, the paper illustrates with a case study - Cargo truck door opening effort check arm - where demand and capacity distributions had its distance to failure mode increased leading to high-quality low-cost alternative in vendor tooling. |
Simulation of Outer Door Handle and Latch Responses in Side Impact using Component Test Methodology | A dynamic component test methodology using a door sub-system was developed to simulate the outside door handle/latch responses (accelerations and deformations) as in a full-vehicle NHTSA FMVSS 214 side impact test. The test methodology consists of a door sub-system (with door inner components) which is allowed to pivot by means of a hinge at the top of the door. The lateral structural load path affecting the door/rocker response was accounted and simulated (obtained from full-vehicle FE analysis) in this methodology by means of an energy absorbing material (Aluminum honeycomb) of predetermined stiffness. A bullet sled simulating the Moving Deformable Barrier (MDB) surface and stiffness at the same relative location to the door/rocker (as in full-vehicle test) strikes the stationary hinged door at an initial velocity of approx. 30 mph (longitudinal component of crab cart velocity of 33.5 mph). Upon impact, the door sub-system rotates about the hinge simulating both the acceleration at the outer handle and latch, and overall deformation of the door. The front door responses (acceleration and velocity) near outer handle and latch from the component test methodology are compared to full-vehicle for validation. |
Development of Door Module Plate with Long-fiber-reinforced Thermoplastic Polypropylene | These days, many new applications for long-fiber-reinforced thermoplastic Polypropylene (PP-LFT) have been coming in the worldwide automobile market. Main issue of this paper is to explain how PP-LFT door module plate was developed, which processes were executed, and what kind of advantages we can get, once it is used as door module plate. Some of steel parts in the car have been changed to the reinforced PP-LFT with weight-saving. Change of material can make modularity more efficient, and then improvement of manufacturing process results in cost-saving. Stress analyses and MoldFlow analyses have been performed to choose the optimized conditions and a product model. Then various tests including waterproof test, drop-weight test and stiffness test have been executed to check if the weight-reduction is suitable for mass-production. PP-LFT door module plates including 40% glass-fiber were used in this paper using above mentioned methods, and, as a result, it is proved to get 21.5% weight reduction of plate and 12% reduction of door module assembly versus conventional steel module plates. |
CAE Virtual Door Slam Test for Plastic Trim Components | Visteon has developed a CAE procedure to qualify plastic door trim assemblies under the vehicle door slam Key Life Test (KLT) environments. The CAE Virtual Door Slam Test (VDST) procedure simulates the environment of a whole door structural assembly, as a hinged in-vehicle door slam configuration. It predicts the durability life of a plastic door trim sub-assembly, in terms of the number of slam cycles, based on the simulated stresses and plastic material fatigue damage model, at each critical location. The basic theory, FEA methods and techniques employed by the VDST procedure are briefly described in this paper. Door trim project examples are presented to illustrate the practical applications and their results, as well as the correlation with the physical door slam KLTs. The successful application of CAE virtual KLT has demonstrated that VDST can reduce product development time and cost, by evaluating and improving the durability of plastic door trim components at early design stage, before a prototype is made and physically tested. |
An Application of Car Crash Test Technology to a Causal Investigation of a Revolving Door Accident | On March 26, 2004, a fatal accident occurred when the head of a 6-year-old child was trapped in a large revolving door in a high-rise building in Tokyo. To investigate the cause of the accident, Prof. Yotaro Hatamura, representing Hatamura Institute for the Advancement of Technology, gathered experts in various fields including architecture and door manufacture, and initiated the ?쏡oor Project,??with the cooperation of the building company. Nissan Motor Co. participated in this project, and conducted load measurement tests on various doors. Applying car crash test technology, including production of special door test dummies and high-speed photography, it was possible to simulate the accident while taking human movement into account. As a result, we obtained important data for accident cause investigation. In this paper, we report the results of application of car crash test technology through an introduction of test results on various doors, and envisage the possibility of future contribution of this technology to man-machine safety issues. |
Modeling of Door Slam Noise Index by using Sound Quality Metric | Door slam noise is very important sound, because Door Slam noise gives a big effect in high-class feeling of vehicle and brand identity. But it is very difficult to analyze door slam noise by traditional analysis and overall sound level. Moreover, the short occurrence time of Door Slam noise makes the analysis more difficult. In this paper, we used the latest developed sound quality methods for analyzing Door Slam noise. And we had performed jury test for luxury vehicles. After that we had carried out correlation analysis between objective analysis and subjective test. Finally, we could suggest Door Slam noise Index by linear regression analysis. |
Simple Test Method for Squeak & Rattle Evaluation of Door Trim by Using Statically Repeated Loading Robot Arm | Recently, major car maker is specified squeak and rattle test method for subsystems or components by objective method. Generally these test method is focused on vibration environmental conditions. Especially, door trim which is located close to occupant is required additional test for squeak and rattle which is produced by occupant's interaction with door trim. To evaluate this condition, generally it can be tested by subjective method such as striking or pushing and twisting several positions of door trim. Dosing so is very time consuming and including variation results as different decisions. So, this paper suggest a new approach for evaluating squeak and rattle which is relating occupant contacting conditions to interior part, especially interior door trim. Multi-axis robot arm is examined to push automatically several points of door trim. Subjective response index for noise is checked at each point and compared with objective values which are evaluated by acceleration level of vibration. Results on subjective and objective method show that they have similar trend at each test point and is thus to adapt to new test method. |
Blind Spot Monitoring by a Single Camera | A practical and low cost Blind Spot Monitoring system is proposed. By using a single camera, the range and azimuth position of a vehicle in a blind spot are measured. The algorithm is based on the proposed RWA (Range Window Algorithm). The camera is installed on the door mirror and monitoring the side and rear of the host vehicle. The algorithm processes the image and identifies range and azimuth angle of the vehicle in the adjacent lane. This algorithm is applied to real situations. The 388 images including several kinds of vehicles are analyzed. The detection rate is 86% and the range accuracy is 1.6[m]. The maximum detection range is about 30[m]. |
Optimization of MAC Side Window Demister Outlet by Parametric Modelling through DFSS Approach | In recent years clearing the mist on side windows is one of the main criterions for all OEMs for providing comfort level to the person while driving. Visibility through the side windows will be poor when the mist is not cleared to the desired level. ?쏻indows fog up excessively/don't clear quickly??is one of the JD Power question to assess the customer satisfaction related to HVAC performance. In a Mobile Air Conditioning System, HVAC demister duct and outlet plays an important role for removing the mist formation on vehicle side window. Normally demister duct and outlet design is evaluated by the target airflow and velocity achieved at driver and passenger side window. The methodology for optimizing the demister outlet located at side door trim has been discussed. Detailed studies are carried out for creating a parametric modeling and optimization of demister outlet design for meeting the target velocity. In this methodology, a parametric modeling of demister outlet design using the factors such as length, width, vane angles and demister outlet to window angle is created using CATIA. Design for six sigma methodologies is followed for robust optimization and arrive at the combination of appropriate design factors which influences the velocity at side windows. L18 orthogonal design array matrix has been created and flow simulations are carried out using the commercial CFD software STAR CCM+. The impacts of each design factors and levels on the side window velocity have been analyzed extensively and best combination of design factors have been found out. Parametric modelling of demister outlet significantly aids in reducing the manual design time for simulation by 50% and DFSS approach helps in finding out the optimized design factors of demist outlet during the design phase of new programs. |
A New Method of Characterizing Wind Noise Sources and Body Response for a Detailed Analysis of the Noise Transmission Mechanism | Interior noise caused by exterior air flow, or wind noise, is one of the noise-and-vibration phenomena for which a systematic simulation method has been desired for enabling their prediction. One of the main difficulties in simulating wind noise is that, unlike most other noises from the engine or road input, wind noise has not one but two different types of sources, namely, convective and acoustic ones. Therefore, in order to synthesize the interior sound pressure level (SPL), the body sensitivities (interior SPL/outer source level) for both types of sources have to be considered. In particular, sensitivity to the convective input has not been well understood, and hence it has not been determined. Moreover, the high-frequency nature of wind noise (e.g., the main energy range extends up to 4000 Hz) has limited the effective application of CAE for determining body sensitivities, for example, from the side window glass to the occupants??ears. This paper presents a new approach to the analysis of wind noise which has been restricted by the intrinsic nature of the noise sources (i.e., a mixture of convective and acoustic components). To cope with this dual-input complexity, a new transmission model was built to treat noise sources characterized simply as ?쐄orces??impinging upon the body surfaces regardless of the type of source and noise transfer functions (NTFs) employed as body sensitivities to the forces. This model enables a quantitative synthesis of interior noise and also a contribution analysis of the sources and/or body sensitivities with high accuracy. |
Vibration Design of Experiments with Varying Factors on a Panel-Beam System | Both vehicle roof systems and vehicle door systems typically have viscoelastic material between the beams and the outer panel. These materials have the propensity to affect the vibration decay time and the vibration level of the panel with their damping and stiffening properties. Decay time relates to how pleasant a vehicle door sounds upon closing, and vibration level relates to how loud a roof boom noise may be perceived to be by vehicle occupants. If a surrogate panel could be used to evaluate decay time and vibration level, then a design of experiments (DOE) could be used to compare the effects of different factors on the system. The purpose of this paper is to show the effect of varying test factors on decay time and vibration level on a panel-beam system with viscoelastic material applied. The results were calculated using DOE software, and they were used to construct optimized systems for validation testing. The test regimen used a modal hammer to excite the system and a piezoelectric accelerometer to measure the response. The input force measured with the modal hammer was used to normalize the structural responses. The conclusions of this work are presented and examined. |
Interior Noise Reduction in a Passenger Vehicle through Mode Modulation of Backdoor | Inside cabin of a passenger car, low frequency booming noise still presents a major hurdle for NVH engineers to fine tune a vehicle. Low frequency booming noise is presently taken care with addition of mass damper and large reinforcements. These conventional countermeasures add weight to the vehicle as well as increase the overall production cost. The study presented in this paper proposes a countermeasure model that not only reduces the booming noise but also avoids any weight and cost addition. It has been focused for low frequency booming noise around 30 ??40 Hz. Within the range mentioned, one of the major reasons for booming noise in hatchback models is the bending resonance of backdoor. By modifying the mode of the backdoor in such a manner that it cancels the effect of bending on the vehicle acoustic cavity, improvement can be achieved in terms of sound pressure level at the driver?셲 right ear location (DREL). Present study utilizes an innovative approach to change the bending mode of the backdoor into twist mode. This has been achieved by offsetting the latch and striker assembly from conventional center location to either side on the transverse axis. The study has been done on a correlated full vehicle trimmed model of a subject vehicle. Maximum improvement of 6 dB(A) has been achieved through the proposed countermeasure. The countermeasure has been applied horizontally to all hatchback models having a backdoor that opens downside-up. The effect of the countermeasure was found to be substantial. |
Novel Aircraft Ground Operation Concepts Based on Clustering of Interfaces | The projected uptick in world passenger traffic challenges the involved stakeholders to optimise the current aviation system and to find new solutions being able to cope with this trend. Since especially large hub airports are congested, operate at their capacity limit and further extensions are difficult to realise. Delays due to late arrival of aircraft or less predictable ground operation processes disrupt the airport operations in a serious way. Various concepts improving the current turnaround processes have been presented thus far, whereby radical aircraft design changes have little chances for realisation in the short term. By maintaining the established overall aircraft configuration, the concepts promote higher probability to become commercially available for aircraft manufactures and operators. Based on a clustering of aircraft interfaces, such as doors and service panels, for state-of-the-art passenger aircraft, concepts targeting to reduce the required resources and time are presented. First studies show that relocating and installing wider passenger doors allow shortening the passenger egress and ingress process by up to 55% compared to current short-to-medium haul aircraft. From a cabin layout point of view, a merger of two galleys and spatial separation from the cabin entrance area would enable a parallelisation of de-/boarding and catering operations which save up time to 20%. The implementation of these single improvements radically shortens the average turnaround time by almost 55% for a full-service carrier and 32% for a low-cost carrier scenario. Furthermore, weight penalties due to additional installed aircraft systems are translated into block fuel deltas of around +0.3% on a 500 nm (926 km) trip. The presented concepts promote a large improvement potential to turnaround time with minor-to-moderate aircraft modifications as well as a higher level of process robustness and thus have the potential to increase airline revenues. |
Design Methodology of an Automotive HVAC Mechanism and Its Numerical Validation Using Multibody Simulation | In order to ensure a comfortable space inside the cabin, it is very essential to design an efficient heating ventilating and air-conditioning (HVAC) system which can deliver uniform temperature distribution at the exit. There are several factors which impact on uniformity of temperature distribution. Airflow distribution is one of the key parameter in deciding the effectiveness of temperature distribution. Kinematics links and linkage system typically termed as ?쁬echanism??is one of the critical sub-systems which greatly affects the airflow distribution. It is not the temperature uniformity but also the HVAC temperature linearity also depends on airflow distribution. Hence the design of mechanism is incomparably of paramount importance to achieve the desired level of airflow distribution at HVAC exit. The present paper describes the design methodology of automotive HVAC mechanism system. To this context various parameters which contribute in designing the mechanism were studied and then a layout was made in CAD. Further the design was evaluated numerically using the MBD (multibody dynamics) of Hypermesh software from which torque to drive the mechanism was predicted as well the reaction force at doors. The design was fine tuned to reduce the operating effort. Finally the predicted operating effort was validated by making the physical sample and it is found that numerical results are in good agreement with that of experimental results. So adoption of such methodology in the early stage of design ensures better and better design of automotive HVAC system. |
Closures weatherstrips with variable cross sections | Closures systems performance is a trade-off between NVH (Noise, Vibration and Harshness) and DCE (Door Closing Efforts) requirements. Dynamic sealing performance and sheet metal rigidity are the key contributors for a stable system. The seals actuate like a spring on the system. Higher seal load is good for NVH performance, adding more dumping to the system, but it will negatively affect DCE, as it will demand additional energy to close the system. Nominal seal load must be defined to achieve a balance between these attributes. This study is about dynamic sealing profiles with variable seal load, which provides tunable solutions to address the trade-off between NVH and DCE on the side doors or rear closures. Dynamic sealing weatherstrips are made of sponge EPDM extruded profiles with a specified load, defined by its CLD (Compression Load Deflection), which is given by the cross section design. While standard extrusion process produces a single cross section profile, a new extrusion technology provides the possibility of varying the profile cross section along the extrusion, thus the possibility to have different CLDs along the length of door perimeter. This technology can assist on the issues that demand quick solutions on vibrations and load relieves, providing good results for these critical attributes. Timing and costs are very attractive as well on the small car segments. |
Aeroacoustics of Heavy Duty Truck Side Mirrors - An Experimental Study | Side mirrors are a known source of aerodynamically generated noise in vehicles. In this work we focus on mirrors for heavy duty trucks, they are large, often not designed with main focus on aero-acoustics and are located in a cumbersome position on the up-right A-pillar of European trucks. First the test method itself is discussed. To allow fast and cost effective design loops a bespoke vehicle, where the powertrain is separated from the cab, is developed. This vehicle can be run on a standard test track. While running the tests the wind speed is monitored, any variations are then compensated for in the post processing allowing averaging over longer time periods. For the mirror tests the door of the vehicle was especially trimmed to reduce other transmission paths into the cab than the side window. Additionally other possible aeroacoustic sources were reduced as much as practically possible. The generated wind noise was monitored with surface microphones both on the mirror (in the wake) and on the window. Additionally arrays of microphones were placed inside the cab and also accelerometers on the window. First the method is evaluated using a dummy mirror that basically is a Strouhal tone generator. Then actual mirrors were tested. It is seen that although the hydrodynamic turbulence noise dominates at the surface microphones on the window, the noise that actually is seen inside the cab is the acoustic sources generated by the separation around the mirror and A-pillar and convected at the speed of sound to the window. |
Localization of BSR Noise Source Using the Improved 3D Intensity Method | A three-dimensional (3D) sound intensity probe is used to identify the trim components generating buzz, squeak, and rattle (BSR) noise in a vehicle interior. The 3D intensity probe has the advantages of compact overall size, small number of microphones, and low-frequency detection capability. Although the 3D sound intensimetry has been not popularly applied in practical problems due to various bias errors, a new error compensation method is adopted in this work, substantially improving the estimate?셲 precision. Linearization of the phase function of the cross-spectral density function between a set of two microphones is used to calculate the intensity avoiding spectral bias error, and an error map for spatial angles is used to compensate for the difference in directivity index around the microphone array. An intensity probe with an even microphone spacing of 30 mm in tetrahedral arrangement is used for the source localization. The interior space is usually a nearly dead room in terms of absorption, but the reverberation effect cannot be neglected due to the small space. Experiments are conducted by using the artificially generated and edited signals pertaining the typical characteristics of each BSR noise. Various source positions are selected, such as the instrument panel, door hinge, seat, etc., and the sound levels of the source and background are changed. The estimated bearing angles of the noise sources are analyzed on a two-dimensional plot. It is found that the localization error is generally less than 6째, which demonstrates the full possibility of using this improved 3D intensity technique for the localization of BSR noise sources in the real time. |
NVH Analysis of Lightweight Steel Components in Full Vehicle | With tighter environmental regulations, as well as political and public opinion pressure, the reduction of automotive polluting gas emissions is subject to intense debates and interests. Before a potential transition to full electrical vehicles as the long term solution, the reduction of mass remains of prime importance to permit direct reduction of emissions in internal combustion engine (ICE) vehicles. In addition to the challenges of structural integrity and safety issues, the acoustical and vibration performance of vehicles can be greatly influenced by mass reduction. This article presents a case study of lightweight design of an automotive door with a high strength steel thin gauge outer panel. An experimental comparison between a reference and a lightweight door was conducted in a complete vehicle, allowing assessing the potential effect of the mass reduction on the acoustic and vibrational performances. Several conditions were assessed: rolling on different surfaces, transient events such as heavy vehicle crossing and door closing events. The comparison method included the determination of main transfer paths on the full vehicle. The study indicated that the different acoustic and vibration performances of the vehicle were preserved. |
Full Vehicle NVH CAE Methodology Development to Address Tailgate Rattling on a Future Tata SUV | In recent years, car manufacturers have been working intensively on new ways to improve the quality of interior trims. Elimination of squeak and rattle has become one of the main concerns for car manufacturers lately, given the significance of these incidences in customers' perception of overall quality. Traditionally, rattle problems are found and fixed with physical tests at the late design stage, mainly due to lack of up-front CAE simulation prediction methodology and tools availability. This article presents a finite element based methodology for the improvement of rattle performance of a vehicle tailgate. In this study, appropriate finite element (FE) modeling technique was introduced to accurately predict occurrence of tailgate rattle. Simulation process using commercial software ?쏯astran??employing modal and forced frequency response analyses was illustrated. Design modifications were incorporated for performance improvement of rattling on present and future SUVs. The simulation methodology and results were validated with experiments on an existing SUV model, with BSR inputs at left rear tire and acceleration responses measured on body and tailgate. Usefulness of this study to predict tailgate rattling in future SUVs was underlined with an example. |
A Test Methodology for Vehicle Wind Noise Reduction and Acoustic Quality Improvement | Aeroacoustics of vehicles is becoming an important design criterion as it directly affects passenger?셲 comfort. The wind noise at highway speeds (>80 KMPH) is a critical quality concern under normal and crosswind conditions and dominant factor in assessing acoustic comfort of the vehicle. Wind noise is caused by the vortex air flow around a vehicle body and air leakage through the sealing gaps of attached parts. This majorly contributes to high frequency noise (>250 Hz). Accurate identification and control of noise sources and leakage paths result in improved acoustic comfort of the vehicle. In this paper, aero-acoustic quality characteristics of validation prototype vehicle are studied. The major wind noise sources and leakage paths in the vehicle are identified through in-house blower set up in the semi anechoic room. The overall wind noise level and articulation index of vehicle at various speeds are determined through on- road measurements. The improvement in the vehicle articulation index (AI) by 14% and reduction in noise level by 4 dB (A) are achieved through design modification of seals, door structure and trim parts. |
Design of Automotive Structures Using Multi-Model Optimization | The use of structural optimization in the design of automotive structures is increasingly common. However, it is often challenging to apply these methods simultaneously for different requirements or model configurations. Multi-model optimization (MMO) aims to simplify the iterative design process associated with optimizing multiple parts or configurations with common design variables especially when conflicting requirements exist. In this paper, the use of MMO is demonstrated to evaluate the feasibility of an automotive door concept using an alternative material. |
Vibration Fatigue for Chassis-Mounted, Cantilevered Components | Vehicle chassis mounted cantilevered components should meet two critical design targets: 1) NVH criterion to avoid resonance with road noise and engine vibration and 2) satisfied durability performance to avoid any incident in structure failure and dysfunction. Generally, two types of testing are performed to validate chassis mounted cantilevered component in the design process: shaker table testing and vehicle proving ground testing. Shaker table testing is a powered vibration endurance test performed with load input summarized from real proving ground data and accurate enough to replicate the physical test. The proving ground test is typically performed at critical milestones with full vehicles. Most tests are simplified lab testing to save cost and effort. CAE procedures that virtually replicate these lab tests is even more helpful in the design verification stages. A method for defining load input, Power Spectral Density or Sine Sweep, to predict the fatigue life of chassis component will be discussed. The CAE process for this topic, with an air suspension compressor support bracket as an example, is presented for vibration stress and fatigue as well as a process to predict and correlate a vibration shaker table key life test. |
Simulation and Optimization Driven Design Process for S&R Problematic - PSA Peugeot Citro챘n Application for Interior Assembly | NVH (Noise Vibration & Harshness) is one of the main focus areas during the development of products such as passenger cars or trucks. Physical test methods have traditionally been used to assess NVH, but the necessity for reducing cost and creating a robust solution early in the design process has driven the increased usage of simulation tools. Development of well-defined methods and tools for NVH analysis allows today?셲 OEMs to have a virtual engineering based development cycle from concept to test. However, a subset of NVH problems including squeak and rattle (S&R) have not been generally focused upon. In a vehicle, S&R is a recurring problem for interior plastic parts such as an instrument panel or door trim. Since 2012, Altair has been developing S&R Director (SnRD), which is a solution that identifies and combats S&R issues by embedding the Evaluation-Line (E-Line) methodology [1] [2]. This methodology is based on industry best practices, as described in the paper SAE 2012-01-1553. This simulation based approach consist of predicting the risk of S&R for trim parts, identifying the root causes, and proposing solutions to the projects via robustness analysis and optimization. This type of simulation integrates design & manufacturing data (GD&T) as well as advanced material testing data. |
Cabin-Ambient Air Exchanges and Their Relation to In-Vehicle CO 2 Concentration | It is common for users of commuting passenger cars in Thailand to use the vehicle?셲 HVAC (Heating, Ventilating and Air Conditioning) system predominantly in recirculation (REC) mode. This minimizes the compressor work, thereby saving fuel, and reduces dust and odor infiltration into the vehicle cabin. The car windows are rarely opened for ventilation purposes, except for exchanges at service stations such as garage entrances and tollway booths. As such, there are few opportunities for fresh air to enter the cabin with the consequent accumulation of CO2 in vehicle cabins due to occupants??exhalations being well documented. Field experiments conducted showed that the in-vehicle CO2 concentrations could reach up to 15 times that of the ambient concentration level during typical city commutes. Preliminary experiments were also conducted to quantify the air exchanges between the cabin and the ambient when the doors are opened for occupant egression. The results indicated that the amount of air exchange depends on the prevailing wind speed and direction, the number of doors opened, and the duration of the door opening. |
Prediction of Mirror Induced Wind Noise Using CFD-FEM Approach | Wind noise is becoming important for automotive development due to significant reductions in road and engine noise. This aerodynamic noise is dominant at highway speeds and contributes towards higher frequency noise (>250Hz). In automotive industry accurate prediction and control of noise sources results in improved customer satisfaction. The aerodynamic noise prediction and vehicle component design optimization is generally executed through very expensive wind tunnel testing. Even with the recent advances in the computational power, predicting the flow induced noise sources is still a challenging and computationally expensive problem. A typical case of fluid-solid interaction at higher speeds results into broadband noise and it is inherently an unsteady phenomenon. To capture such a broad range of frequency, Detached Eddy Simulation (DES) has been proven to be the most practical and fairly accurate technique as sighted in literature. Present work talks about the application of Detached Eddy Simulation (DES), as a computationally faster and cheaper method for predicting the flow and sound generation. In the present case a mirror mounted on SUV has been investigated numerically using Finite Volume Code, FLUENT in flow domain and FEM methodology with appropriate aero acoustic analogies in structural domain. In this study, the effect of mirror configuration on the vehicle interior noise has been presented. The analysis has been carried out on baseline mirror, new mirror (door mounted) and no mirror cases. The average sound pressure level inside the vehicle observed to be reduced by 17% with door mounted mirror compared to baseline mirror case. |
Stiffness Simulation Techniques and Test Correlations in Automotive Interior Cockpit Systems (IP, Door Trim and Floor Console Assembly) | An automotive cockpit module is a complex assembly, which consists of components and sub-systems. The critical systems in the cockpit module are the instrument panel (IP), the floor console, and door trim assemblies, which consist of many plastic trims. Stiffness is one of the most important parameters for the plastic trims' design, and it should be optimum to meet all the three functional requirements of safety, vibration and durability. This paper presents how the CAE application and various other techniques are used efficiently to predict the stiffness, and the strength of automotive cockpit systems, which will reduce the product development cycle time and cost. The implicit solver is used for the most of the stiffness analysis, and the explicit techniques are used in highly non-linear situations. This paper also shows the correlations of the CAE results and the physical test results, which will give more confidence in product design and reduce the cost of prototype testing. |
A Case Study for Automotive Door Closing Effort Uncertainty Analysis based on Monte Carlo Simulation Method | Quality in the automotive industry means development and manufacturing of vehicles whose specifications meet customer requirements. Among many other quality issues, door closing effort is a vehicle characteristic that strongly affects the customer first opinion about vehicle design. The door closing effort is affected by uncertainties in materials and manufacturing processes. The present paper presents a reliability-based method to evaluate the uncertainties associated with door closing effort due to manufacturing processes. A formulation is proposed to calculate that energy based on three components: energy used to compress air into the vehicle, energy used to compress the sealing and energy used to lock the door. In order to quantify the probability that the door closing effort is greater than a target value, reliability analysis concepts are used based on the uncertainties associated to latch position. The Monte Carlo simulation is used to define door closing effort variability due to variation of the side door latch position. That analysis allows defining maximum allowable latch and striker position variability in order to keep door closing effort below a target value. The latch position uncertainty is modeled by a probability distribution defined based on data collected from the assembly process. The probability of having a door closing effort magnitude lower than a target value is then calculated. Simulated distribution is compared to experimentally door effort analysis showing very good agreement between them. The simulation based model is used to evaluate the feasibility of manufacturing processes changes to reduce door closing effort. |
Simulating Human Body Touch Automotive Tests Using Industrial Robot & Intelligent Grippers Equipped With Sensors | All Automotive companies conduct various performance and Endurance tests on automotive bodies, doors by using Pneumatic Actuators. These Actuators can only give linear or rotary motion. Therefore these can neither simulate the complex motion of Human arm nor can they simulate the Force and pressure induced by the Human palm or Human back on the body domain parts. Each test need to have different test setup. This paper discusses how a system of industrial Robot coupled with intelligent Gripper with sensors and feedback signal to robot can be used to simulate the effect of Human touch during testing. |
Motor Control in Auxiliary Drive Systems How to Choose the Best Fitting Electronic Solution | In modern vehicles, the number of small electrical drive systems is still increasing continuously for blowers, fans and pumps as well as for window lifts, sunroofs and doors. Requirements and operating conditions for such systems varies, hence there are many different solutions available for controlling such motors. In most applications, simple, low-cost DC motors are used. For higher requirements regarding operating time and in stop-start capable systems, the focus turns to highly efficient and durable brushless DC motors with electronic commutation. This paper compares various electronic control concepts from a semiconductor vendor point of view. These concepts include discrete control using relays or MOSFETs. Furthermore integrated motor drivers are discussed, including system-on-chip solutions for specific applications, e.g. specific ICs for window lift motors with LIN interface. In most cases, system suppliers have the choice between several electronic partitioning concepts, based on specific technical and economic conditions up to given specific preferences of the supplier. |
Supporting Hinge Arrangement for Heavy Weight Side Opening Tailgate | The tailgate is the fifth or the rearmost door of an SUV (Sports Utility Vehicle)[1]. It can be side opening or top opening. It is attached to the BIW (Body In White) with two hinge arrangement. The hinges are designed to take the cantilever load of a normal side opening tailgate along with the passenger ingress/egress load. This means that apart from the doors own weight, the hinges have to take the extra load which a passenger exerts on it by resting his/her forehand on the handle. The hinges are designed to take these loads and under normal circumstances, they do not fail for acceptable number of cycles of opening and closing of the tailgate. But in case of an armored vehicle side opening tailgate, it is quite a challenge for the normal hinges to take the heavy load of the tailgate along with passenger ingress / egress load. The normal hinges (Refer figure-1) obviously fail under such heavy loads either in their design or material configuration. To take this extra load, designers had to think of an innovative arrangement/concept that was simple yet convenient from retrofitting point of view on an armored vehicle configuration. Such an innovation was thought off, designed and implemented successfully on first prototype of the armored SUV. Figure 1 Figure showing the view of a portion of a tailgate from outside of the SUV. Normal hinges are visible as shown in yellow color. Also visible is the aperture plate of the arrangement in blue. (BIW not shown.) |
An Improved Methodology for Calculation of the Inertial Resistance of Automotive Latching Systems | This paper outlines an improved methodology to perform calculations to verify the compliance of automotive door latch systems to minimum legal requirements as well as to perform additional due diligence calculations necessary to comprehend special cases such as roll over crashes and locally high inertial loadings. This methodology builds on the calculation method recommended by SAE J839 and provides a robust and clear approach for application of this method to cable release systems, which were not prevalent at the time J839 was originally drafted. This method is useful in and of itself but its utility is further increased by the application of the method to a Computer Aided Design (CAD) template (in this case for Catia V5), that allows some automation of the calculation process for a given latch type. This will result in a savings of time, fewer errors and allows for an iterative concurrent analysis during the design process. |
The Topology Optimization Analysis on Rope-Wheel Glass Lifter | Glass lifter is a key part of automobile door system. Guide rail is the carrier of glass lifter, and it bears various load cases when glass lifer works. Mass, stiffness and natural frequencies are the factors that influence the performance of glass lifter. In order to design a lighter and reasonable glass lifter, topology optimization methods are studied in this paper. In a rope-wheel glass lifter, design domain is determined by the mechanical structure and working conditions. Firstly, the single target continuum structure topology optimization mathematic models of guide rail are built in this paper, and analysis of multi-stiffness topology optimization are carried out accordingly in which volume fraction is set as 0.4, 0.5 and 0.6. These models are based on SIMP (Solid Isotropic Material with Penalization) theory. Secondly, multiobjective topology optimization models of guide rail are built to consider the influence of dynamic characteristics, and volume fraction is also set as 0.4, 0.5 and 0.6. These models are based on the weighted compromise programming approach. A new formula is proposed in this paper, and optimization objectives are static stiffness and dynamic frequencies, constraint is volume fraction. Comparing these two methods, single target optimization method is more efficient, whereas the structures of optimized guide rail are not reasonable due to the appearance of a large minimum density area in the middle of guide rail. The topology optimization method of considering dynamic characteristic makes the structures of the optimized guide rail more reasonable. The structural load path is clear, and more triangular structures generate which strengthen stiffness of the structure. In addition, values of optimized compliance are lower than that of the single target topology optimization and the first three order frequencies of multi-objective topology optimization are higher than that of single target. So the topology optimization method of multi-objectives makes guild rail have better rigidity and vibration characteristics, which provides a valuable basis and method for the design of guild rail. |
Development of Paint-Less Black Gloss Decorative Technology for Frame Molding | The need to add more color variations to the traditional black gloss has increased globally in recent years. The intention is for automobile manufacturers to differentiate their products in terms of appearance design. The most noticeable trend is to add embellishment around the front grill. The same trend can be seen in the areas around vehicle doors. It is most common to use a coating material to emphasize the black gloss. However, in overseas countries it is a challenge to meet the required appearance quality, and under the current circumstances CKD is imported from Japan to meet such requirements. Recently, a new film-transfer technique has been established that can express black gloss as well as any coating material by transferring the roughness of the film surface. It is achieved by crimping the PET film onto the vinyl-chloride surface after the extrusion molding is performed. Moreover, we have successfully localized this technique and reduced the manufacturing cost. Thus, the development process will be described. |
Closure Slam CAE Method Investigation for Automobiles | In the current scenario, the major thrust is to simulate the customer usage pattern and lab test using virtual simulation methods. Going ahead, prime importance will be to reduce the number of soft tool prototype for all tests which can be predicted in CAE. Automotive door slam test is significantly complex in terms of prediction through simulation. Current work focuses on simulating the slam event and deriving load histories at different mounting locations through dynamic analysis using LSDyna. These extracted load histories are applied to trimmed door Nastran model and modal transient analysis is performed to find the transient stress history. This approach has a significant advantage of less computation time and stress-convergence with Nastran for performing multiple design iterations compared to LSDyna. Good failure correlation is achieved with the test using this approach. Using these load histories, design improvements are evaluated and robustness of the approach is validated. An attempt is made to extract load histories using virtual mule in LSDyna. So, at an early stage in a project, using the only hinge and latch CAD location with closure mass, inertia and center of gravity, the load histories can be extracted and design improvement can be evaluated. Detailed analysis of predicting over-slam through simulation and effect of the position of glass on strain at different locations is highlighted. |
A Multi-Function Automotive MM-Wave Radar Design | A 24GHz multi-function assist system has been developed for advanced automotive radar, which includes different applications in Blind Spot Detection (BSD), Lane Change Assist (LCA), Doors Open Warning (DOW) and Rear Cross Traffic Alert (RCTA). The multi-function radar is based on the micro-strip antenna, which has a reasonable design on main-lobe and side-lobes. According the antenna, the radar can operate in mid-range mode with a high gain and a narrow beam width, whilst performing well in short-range and wide-angle mode. |
Prediction of Aeroacoustical Interior Noise of a Car, Part-1 Prediction of Pressure Fluctuations on External Surfaces of a Car | A wall-resolving Large Eddy Simulation (LES) has been performed by using up to 40 billion grids with a minimum grid resolution of 0.1 mm for predicting the exterior hydrodynamic pressure fluctuations in the turbulent boundary layers of a test car with simplified geometry. At several sampling points on the car surface, which included a point on the side window, the door panel, and the front fender panel, the computed hydrodynamic pressure fluctuations were compared with those measured by microphones installed on the surface of the car in a wind tunnel, and effects of the grid resolution on the accuracy of the predicted frequency spectra were discussed. The power spectra of the pressure fluctuations computed with 5 billion grid LES agreed reasonably well with those measured in the wind tunnel up to around 2 kHz although they had some discrepancy with the measured ones in the low and middle frequencies. The Dynamic Smagorinsky Model (DSM) was adopted for the subgrid-scale turbulence model of LES while the resulting spatially-filtered Navier-Stokes equations of the incompressible fluid flow were solved by a Finite Element Method. In the second paper of this series of studies, the hydrodynamic pressure fluctuations computed on the car surfaces will be used as the unsteady loading for computing the panel vibration of the test car by using Finite Element Method, and finally the interior acoustical fields will be predicted by solving the Helmholtz equation for sound propagation. The contribution from the external acoustical field to the interior noise, which was not simulated by the present incompressible LES-based approach, was estimated based on the acoustic analogy, and was confirmed to be negligibly small compared with those from the hydrodynamic loading in the present case. |
Construction and Kinematics of Automotive Side Door Latch Mechanisms | Automotive side door latches are considered safety-critical systems due to both federal and automotive OEM regulations. The paper presents a kinematical study, in terms of degrees of mobility, and the basic construction for an example mechanism utilized as an automotive side door latch. This system is represented and approximated with mechanisms with articulated bars, cams and gears. Mobility calculations for such type of mechanisms involve both the determination and the investigation of all involved kinematical elements and the nature of their mobile restraints (called kinematical couples). By applying the principles and the methods described in this paper similar investigations in terms of the degree of mobility for other side door latch design applications can be investigated. |
Multi-Objective RBDO for Automotive Door Quality Design | This paper develops a multiobjective optimization methodology for automotive door quality design under uncertainty, in which the tradeoffs between two competing objectives need to be considered. Two important quality issues, door closing effort and wind noise, are of concern and the corresponding probabilities of unsatisfactory performance are considered in the optimization. Model-based reliability analysis methods are used to compute these probabilities. Both component and system-level reliability analyses need to be performed in RBDO. While a first order reliability method (FORM) is found adequate for the reliability estimation with respect to door closing effort, an adaptive Monte Carlo simulation method is found suitable for reliability analysis of the wind noise problem with multiple limit states. An efficient decoupled RBDO approach is used to solve the multiobjective optimization and the Pareto frontier is generated for decision-making. The proposed method can be applied to solve a wide variety of RBDO problems with competing objectives and reliability constraints at both component and system levels. |
The Application of Magnesium Die Casting to Vehicle Closures | During the last decade, advances in magnesium die casting technology have enabled the production of large lightweight thin walled die castings that offer new approaches for low investment body construction techniques. As a result, many OEMs have expressed an interest in magnesium door closure systems due to investment reduction opportunities, coupled with potential weight savings of up to 50%. However, for such applications, product engineers are faced with the challenge of designing for stiffness and strength in crash critical applications with a material of lower modulus and ductility compared to wrought sheet product. Concept designs for side door systems have been presented in the literature, and indicate that structural performance targets can be achieved. However, to date, series production designs feature a multitude of supplementary sheet metal reinforcements, attached to die castings, to handle structural loads. While this approach can still offer performance benefits, the additional cost of tooling and assembly has a negative impact on both overall weight and the business rationale. On the contrary, the magnesium door concepts presented in this paper describe the development of side door systems designed to replace the bulk of sheet metal stampings by a single magnesium die casting. A summary of the design, analysis, prototyping and testing stages is reported, in addition to the development of a series production door system for a 2004 model year vehicle. A review of manufacturing and test results demonstrate how magnesium can be used effectively in the manufacture of low investment, lightweight vehicle closures. |
Detecting and Classifying Secondary Impacts in Door Closing Sound | One of the primary correlates to customer annoyance with door-closing sound is peak loudness. In addition, customer annoyance also increases with the existence of secondary impacts, such as rattles. While these secondary impacts are typically not seen in the time-varying loudness trace (or other common sound quality metrics), it is often possible to visually identify the impacts in a time-frequency display of the door-closing sound. But the reduction of this display information to a single-number objective metric that agrees with subjective assessments has previously proved elusive. This paper summarizes the recent development and application of an objective metric that agrees with subjective classifications of secondary impacts in door-closing sounds. |
Antenna Embedded Door Handle for Smart Key System | It is necessary for a door handle for the smart-key system to adapt for various door handle structures. The smart-key door handle, of course, should have competitiveness. For developing the next generation of the smart-key door handle, we considered that compact sizing and easy manufacturing are the key issues. Therefore, we tried to use the wire harness as an antenna and a sensor for the smart-key system. Moreover, the bending-forming method has been developed to achieve this idea. We will introduce the development process with the commitment to improve commercial value exampling the smart-key door handle development. |
A Study on the Modelling Technique for the Passenger Out-Of-Position Simulation | There was a regulation to reduce injuries caused by airbags for OOP (Out-Of-Position) impact loading conditions. Also, many tests are needed to meet the regulation regarding design variation. And the main effect of airbag design variable has not been well known. Therefore, numerical simulation modelling method and technique were required to reduce the test numbers and recommend the airbag design guideline for OOP condition. To establish modelling procedure for OOP situations in this paper, simulation model was built and correlated with test. Also, the body block test for airbag cushion correlation, a pendulum test for opening stiffness correlation of airbag door and low risk deployment static test using 3-year-old dummy for OOP simulation correlation were performed. And, airbag door and folding condition were evaluated using full factorial DOE (Design of Experimental) technique. Finally, airbag inflator, vent hole, opening stiffness of door and friction coefficient were evaluated using orthogonal array (L9). From the DOE results, the airbag door modelling was insignificant for In-position situation whereas it was significant for OOP modelling. And the direct folded mesh shows a good correlation for OOP condition. Especially, the direct folded mesh by MOBIS folder was validated. The OOP simulation results had been mainly influenced by the inflator model and airbag door opening stiffness. |
SEA Modeling of A Vehicle Door System | The Door system is one of the major paths for vehicle interior noise under a variety of load conditions. In this paper we consider the elements of the door lower (excluding glass) in terms of noise transmission. Passenger car doors are comprised of the outer skin, door cavity, door inner sheet metal, vapor barrier, and interior trim. Statistical Energy Analysis (SEA) models must effectively describe these components in terms of their acoustic properties and capture the dominant behaviors relative to the overall door system. In addition, the models must interface seamlessly with existing vehicle level SEA models. SEA modeling techniques for the door components are discussed with door STL testing and model correlation results. |
Experimental Study On the Energy Flow Analysis of Vibration of an Automobile Door | The Energy Flow Analysis (EFA) can be effectively used to predict structural vibration in medium-to-high frequency range. In this paper, Energy Flow Finite Element Method (EFFEM) based on EFA has been used to predict the vibration of an automobile door. The predicted results for the frequency response function of the door have been compared with corresponding experimental results. In the experiment, the automobile door has been divided into several subsystems and the loss factor of each subsystem has been measured. The input mobility at a source point has been also measured. The data for the loss factors and the input mobility have been used as the input data to predict the vibration of the automobile door with EFFEM. The frequency response functions have been measured over the surface of the door. The comparison between the experimental results and the predicted results for the frequency response functions showed that EFFEM could be an effective tool to predict the structural vibration. |
Low Frequency Transient CAE Analysis for Vehicle Door Closure Sound Quality | Improvement of vehicle door closure sound quality is one of the major customer wants. It is very desirable to understand how different door elements radiate sound during a door-closing event and how to optimize a door structure to design for a specific sound target. In this paper, a CAE tool is developed based on transient FEA and BEA for the analysis of structural-borne vehicle door closure sound quality in the low frequency range (up to 300Hz). Design sensitivity analysis (DSA) are performed for investigating effects of major design variable changes on the door closing sound quality. A SUV model was studied to validate the simulation results and to demonstrate the capability of the developed CAE tool for providing design guidelines on door closing sound quality. |
The Door Mounted Inflatable Curtain | It has been shown that Inflatable Curtains have the potential to reduce head injuries in side impacts and the system has accordingly been introduced on a growing number of car models. There is also a potential benefit in rollover situations. This paper only consider performance in situations with belted occupants. To date, it has not been possible to implement an Inflatable Curtain in convertible vehicles because they lack a roof. The challenge of the Door Mounted Inflatable Curtain (DMIC) has been to overcome the lack of support and fixation possibilities offered by a roof. This paper includes a description of the DMIC and how it was integrated into the vehicle structure. The paper will also show how to create the space and support needed to utilize the internal stiffness and make it possible to fill the bag in time. The impact attenuation and ejection protection functions of the DMIC will be demonstrated. |
Benefits of a New Concept Window Lift System in a Typically Constrained Door Environment | A new design concept for a mechanism to raise and lower side dropping automotive windows provides greater in-board/ outboard compliance than conventional window lift systems. These design aspects provide advantages over current technologies. Among these advantages are: A reduction and control of vectored load inputs on the associated window lift system, having the effect of improved efficiency. A lower cost construction than conventional devices. A window lift system that is more capable of providing one-touch-up functionality meeting the anti-pinch safety criteria outlined in the Federal Motor Vehicle Safety Standard (FMVSS) 118. Drastically reduced prototyping time. This reduction is achieved by producing a general purpose product, then shaping / modifying it to approximate door geometry. The freedom of the inboard / outboard constraints makes imperfect geometry inconsequential in the evaluation of the prototypes. The method of research includes data collection of comparative systems and demonstrations of performance. a general financial analysis contrasting with conventional systems. direct comparative examples, along with anecdotal examples of actual prototype lead times. This new concept window lift regulator system, known as the Racklift??system, due to its combination of material construction, mechanical drive geometry, low weight, consistently low power consumption, and dual axis directional flexibility, is unique in its ability to address these various functions and quality of operation. The conclusions drawn support the effects of reduced load variation as measured through velocity, current draw, noise variation, and seal wear. The conclusions also demonstrate the financial advantages and rapid prototyping of the device over conventional systems. |
An Assessment of Door Openings in NASS-CDS Resulting From Combined Longitudinal Compressive and Lateral Tensile Latch Loading | The April 1st, 2005 Global Technical Regulation (GTR) [ECE/TRANS/180/Add.1] Working Party for door locks and door retention components reviewed a combination loading static bench test for latch systems (combination test) that is capable of evaluating the strength of the latching systems and is designed to detect fork bolt detent bypass failures. In the combination test, the latch is mounted on a flat steel plate that moves horizontally. The striker is mounted on a vertically moving ram device. During the test, lateral tension of 6,650 N is applied and maintained on the coupled latch-striker system by moving the flat steel plate and then applying a longitudinal compressive force of 16,000 N by moving the striker at a constant rate. A study of field data from the National Automotive Sampling System - Crashworthiness Data System (NASS-CDS) data files for the years 2003 to 2007 was conducted to determine the prevalence of real world crashes with latch/ striker separation due to a loading environment similar to that in the combination loading test. The study also assessed whether requiring door latches to pass this combination test would translate into a significant safety benefit by reducing deaths and injuries that result when a vehicle occupant is ejected from a vehicle during a crash. Data was limited to later model year vehicles (1995+) and to cases that comprised the necessary information needed to determine impact location, direction, and severity. A total of 330 NASS-CDS cases from 2003 to 2007 were coded with at least one door latch/ striker separation. Photographic evidence and crash parameters were utilized to determine whether each door latch/ striker separation was due to loading environments represented by the combination loading test. Of the 330 cases of latch/ striker separations, 290 cases occurred in very severe crash conditions with significant vehicle damage. The latch/ striker separation in these cases was deemed to have resulted from excessive loads and vehicle deformation. Of the remaining 40 latch/ striker separation cases, only 14 had loading conditions similar to that simulated in the combination loading test for latch systems. This study also found that in recent years there has been a trend that clearly reflects a significant reduction in both the number of door latch/ striker separations and the deaths and injuries that are traceable to these failures. As a result of the small number of cases identified and the trend toward reduced numbers of door latch/ striker separations, this study found that imposing a requirement that door latches pass the combination test would prevent 1.38 to 5.37 fatalities and 0.98 to 27.20 serious injuries per year. |
CAD - Based Synthesis of a Window Lifter Mechanism | The kinematic layout is an essential part in the early development phase of an automotive door. Apart from the door opening mechanism, the main focus lies on the synthesis of the window lifter, which has a high impact on the glass shape and on window tightness properties. The main task is to find a proper window motion with respect to the space requirements and the maximum seal deflection. Boundary conditions are given by the shape of the pillars and the window which are mainly styling driven. In this contribution a method is described to compute an optimized motion allowing for all such restrictions. The applied method is based on a CAD platform and combines simulation with parametric-associative design. This leads to a high level of flexibility and simple handling. The presented approach is an example of an upfront design analysis significantly supporting the door development process. |
Pressure Sensor Simulation Capability for Side Impact Sensing Calibration | There is a growing interest in using pressure sensors to sense side impacts, where the pressure change inside the door cavity is monitored and used to discriminate trigger and non-trigger incidents. In this paper, a pressure sensor simulation capability for side impact sensing calibration is presented. The ability to use simulations for side impact sensing calibration early in the vehicle program development process could reduce vehicle development cost and time. It could also help in evaluating sensor locations by studying the effects of targeted impact points and contents in the door cavity. There are two modeling methods available in LS-DYNA for predicting pressure change inside a cavity, namely airbag method and fluid structure interaction method. A suite of side impact calibration events of a study vehicle were simulated using these two methods. The simulated door cavity pressure time histories were then extracted to calibrate the side sensing system of the study vehicle. The calibration result shows that both the airbag method and the fluid structure interaction method are capable of predicting the pressure change inside the door cavity for side impact sensing calibration purposes, albeit the former requires much less computer run time than the latter. |
A Simple Method to Calculate Vehicle Heat Load | The first challenge to properly size a vehicle A/C system is to define the vehicle air conditioning heat load requirement. Within automotive industry, a model to accurately define vehicle heat load is still under development. In this study, a simple method to calculate vehicle heat load is developed. The cooling load temperature differential (CLTD) method[1] is used to calculate the heat gain of a sunlit roof and wall (door). This is done in one step by using ASHRAE data. The calculation presented here takes into account the geometrical configuration of the vehicle compartment including glazing surfaces (shading), windshield and roof angle, and vehicle orientation, Special attention is given to the calculation of direct and diffuse incidence solar radiation through the windshield and skylight glass. The vertical glass' solar heat gain is evaluated by using ASHRAE[1] data. The U value method is used to calculate heat transfer between the outside and inside cabin. Heat gains from infiltration, occupant, and HVAC unit blower motors are considered in the cooling load calculation. The method accuracy was validated using wind tunnel tests. The results showed the predicted cooling load is very close to the tested value, and the deviation between calculated and tested heat loads is smaller with fresh air mode than that with recirculation mode. |
Control of Airborne Road Noise Using Sealers | Noise generated during tire/road interaction has significant impact on the acoustic comfort of a vehicle. One of the most common approaches to attenuate road noise levels consists on the addition of mass treatments to the vehicle panels. However, the acoustic performance of sealing elements is also relevant and has an important contribution to the noise transmission into the vehicle interior. In this paper the correct balance between the mass added to treat vehicle panels and sealing content is investigated. The procedure to quantify the critical road noise transmission paths consists of recording interior noise levels as applied treatment is removed from potential weak areas, such as wheelhouses, floor, doors and body pillars. It is observed that the noise propagation through body pillars has a direct influence on road noise levels. In this case, the use of acoustic sealers placed in the body pillar sections can reduce noise transmission particularly at high frequencies leading to the achievement of desired vehicle acoustic comfort levels. |
Objective chime sound quality evaluation | Customer perception of vehicle quality and safety is based on many factors. One important factor is the customers impression of the sounds produced by body and interior components such as doors, windows, seats, safety belts, windshield wipers, and other similar items like sounds generated automatically for safety and warning purposes. These sounds are typically harmonic or constant, and the relative level of perception, duration, multiplicity, and degree of concurrence of these sounds are elements that the customer will retain in an overall quality impression. Chime sounds are important to the customer in order to alert that something is not accomplished in a right way or for safe purposes. The chimes can be characterized by: sound level perception, frequency of the signal, shape of the signal, duration of the ?쐀eep??and the silence duration. The purpose of this work is to use psychoacoustic parameters and time-frequency tools in order to quantify the sound quality perception of chime sounds like key off headlamp on and the unclosed door with gear out of parking mode. |
A Novel Test Rig for the Aerodynamic Development of a Door Mirror | Door mirrors have a small but measurable contribution to the overall aerodynamic drag of a road vehicle. Typically for passenger cars and SUVs this is in the range 2.5??%. It can be difficult to refine the shape of door mirrors as the improvements are, sometimes, too small to measure with any accuracy. A test rig has been developed which allows a full size door mirror to be tested in a model wind tunnel facility, which has better balance resolution, where the mirror is mounted to a partial vehicle body. This also results in a faster and cheaper method to develop shapes for door mirrors. The rig is described and the initial correlation tests presented. The limitations of the rig and some further applications are discussed. |
Design of Dual Sliding Door for a Small-size Car and Its Validation Using CAE Tools | Sliding doors are usually employed on the rear side of minivans and some large vehicles for easy egress and ingress. Furthermore, dual sliding doors are frequently observed in various concept models. This paper describes design of a dual sliding door for a small-size car. A new sliding mechanism with two sliding contact points is proposed with the B-pillar incorporated in the door structure made of high strength steel. Two sliding tracks are located in the door and the rocker panel. The door linkages first swivel and then slide with the help of the rollers in the tracks to open the door. The sliding mechanism and the door structure were validated using CAE tools such as HyperMesh, MSC/NASTRAN [2] and LS-DYNA[3]. This validation process was divided into three parts: (1) Dynamic Stiffness Analysis or the normal mode analysis to understand the natural frequency response of the door. (2) Static Stiffness Analysis or the Door Sag analysis was conducted to see the structural strength of the door in static loading. Finally, (3) Quasi-static side intrusion analysis was performed to see the resistance of the door structure against an intruding pole. The analysis results showed that the door structure achieved the desired structural performance requirements. |
Automotive Side Glazing for Primary and Secondary Occupant Retention | The occupant retention performance of laminated and tempered side glazing during rollover collisions is analyzed. A brief history of automotive glazing is given, including a discussion of current technology. A summary of glazing failure mechanisms is provided, along with the results of impact and quasi-static pushout testing of undamaged commercial and prototype door windows. The investigation shows that supported laminated side glazing gives performance comparable to windshield glazing and can effect both primary and secondary containment of occupants. Results of documented unplanned rollover collisions and staged rollover tests are presented in support of the conclusions drawn. |
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