Paragraph
stringlengths 6
919
| Details
stringlengths 6
4.93k
|
|---|---|
Sound Quality Prediction Modelling for the Transient Sound of Vehicle Door Latch Closure | Door latch closure noise has contribution on sound quality of vehicle door slam sound. This paper focuses on the modelling of sound quality for door latch closure sound. 24 various latch closure sound samples were recorded to be evaluated subjectively. A novel Dynamic Paired Comparison Method (DPCM) was introduced for subjective evaluation. By eliminating the redundant comparison pairs the DPCM dramatically reduced the evaluation work load comparing to the traditional Paired Comparison Method (PCM). Correlation between subjective evaluation results and psychoacoustic metrics was analyzed to find out the most relevant metrics as inputs for the subsequent prediction model. Besides, the shudder effect induced by multi-impact of latch components during closing movement was also found strongly affecting the subjective perception of door latch closure sound. Therefore, a new metric Shudder Level which is graded in 3 levels describing this shudder effect was developed and then quantified as one of the model inputs. The sound quality of door latch closure was modeled by means of Multi-Linear Regression Function (MLRF) both with and without the Shudder Level. The results show that the model which takes the shudder effect into account gives a better prediction on door latch closure sound quality. |
The Analysis and Control of Aural Discomfort inside a Car at the Instant of Door Closing | With the continuous improvement of vehicle air leakage performance, an aural discomfort phenomenon had been occurred at the instant of vehicle door closing. There are many studies on door closing sound quality in past 20 years, but there is little publications on the study of the aural discomfort due to a transient high air pressure fluctuations. In this paper, the relationships of passenger?셲 aural discomfort produced by interior air pressure fluctuations are systematically studied. The ratio of door surface area to passenger compartment volume and other related parameters such as the cross-sectional area of a vehicle, the air extractor size, and the vehicle body air leakage under positive pressure are also studied through CAE analysis and verified through a large number of objective measurements and subjective vehicle evaluation. Base on this study, a new threshold value of air pressure fluctuation for human aural comfort, and a new objective evaluation index for aural discomfort due to the transient air pressure fluctuations are defined. Some guidelines for the pressure exhaust system design and development to improve the door closing aural comfort of passenger vehicles are provided. |
A Robust Methodology to Predict the Fatigue Life of an Automotive Closures System Subjected to Hinge and Check Link Load | In order to provide an accurate estimation of fatigue life of automotive door hinges and check strap mounting location, it is crucial to understand the loading conditions associated with opening and closing the door. There are many random factors and uncertainties that affect the durability performance of hinge and check strap mount structures in either a direct or indirect way. Excessive loads are generated at the hinge and check arm mounting region during abuse conditions when opening the door. Repeating the abuse conditions will lead to fatigue failures in these components. Most influencing parameter affecting the fatigue performance for the door was the loads due to hinge-check arm sensitivity stoppage and the distance between hinge and check strap attachments. However, the probability of occurrences was low, but the impact is high. In this proposed investigation, Monte Carlo simulation methodology is applied on the randomly selected samples with predicted distribution of all dependent factors to know the fatigue life variations in the hinge mount structure. Weibull distribution is the most efficient way of estimating the fatigue failure or fatigue life. This can be estimated on the basis of the function of the populated size. The mean and standard deviation of the simulated fatigue life converged with a greater number of randomly varied samples. This technique defines the maximum allowable load cycles on the hinges and the check arm mount structure, and their variability. It helps in keeping the door opening efforts below the target value. The fatigue life cycle of the door is predicted closest to the experiments by applying the proposed method on more number of samples. It also keeps the probability of failure under check |
A Study on Optimization of the Cross-Section of Door Impact Beam for Weight Reduction | This paper focuses on the optimization of the cross-section of a panel type impact door beam. The key parameters of the cross-section of the beam were artificially changed by using a geometry morphing tool FCM (Fast Concept Modeler), which is plugged in to CATIA. Then, the metamodel of FE (Finite Element) analysis results was created and optimized using LS-OPT. The ANOVA (Analysis of Variance) analysis of results was carried out to find the factor of weight reduction. Finally, a new cross section concept was proposed to overcome the limitation of old structure. The optimization was carried out for the beam with the final cross-section to have 10 % or more reduction in total weight. |
A Research on Kinematic Optimization of Auto Flush Door Handle System | Today, many car manufacturers and their suppliers are very interested in power-operated door handles, known as auto flush door handles. These handles have a distinguishing feature in terms of the way they operate. They are hidden in door skins and deployed automatically when users need to open the door. It is obvious that it is a major exterior styling point that makes customers interested in the vehicles that apply it. To make this auto flush door handle, however, there lie difficulties. First, because there is no sufficient space inside a door, applying these handles can be a constraint in exterior design unless the structures of them are kinematic optimized. The insufficient space can also cause problems in appearance of the handles when they are deployed. The purpose of this study is to establish the kinematic system of auto flush door handle to overcome the exterior handicaps such as the excessive exposure of the internal area on the deployed position. In order to resolve these issues, the Scott-Russell mechanism is applied to the auto flush handle system, and the key parameters are optimized by the methodology of DFSS dynamic characteristics method. Therefore, the engineering solutions are given to resolve the finger jamming in the handle due to the high speed retraction and the incongruity of the relative retraction speed between the handle and outside mirror. Thus, in this paper, the engineering solutions and optimized criteria to resolve all related issues are introduced to enhance the values of vehicles for customers. |
Robust Assessment of Automotive Door Structure by Considering Manufacturing Variations | The automotive door structure experience various static and dynamic loading conditions while going through an opening and closing operation. A typical swing door is attached to the body with two hinges and a check strap. These mechanisms carry the loads while the door is opened. Similarly, while closing the door, the latch/striker mechanism along with the seal around the periphery of the door react all loads. Typically, computer aided engineering (CAE) simulations are performed considering a nominal manufacturing (or build) tolerance condition, that results in one loading scenario. But while assembling the door with the body, the build variations in door mechanisms mentioned above can result in different loading scenarios and it should be accounted for design evaluation. This paper discusses various build tolerances and its effect on door durability performances to achieve a robust door design. |
CAE Simulation of Automotive Door Upper Frame Deflection Using Aerodynamic Loads | Upper frame deflection of automobile doors is a key design attribute that influences structural integrity and door seal performance as related to NVH. This is a critical customer quality perception attribute and is a key enabler to ensure wind noise performance is acceptable. This paper provides an overview of two simulation methodologies to predict door upper frame deflection. A simplified simulation approach using point loads is presented along with its limitations and is compared to a new method that uses CFD tools to estimate aerodynamic loads on body panels at various vehicle speeds and wind directions. The approach consisted of performing external aerodynamic CFD simulation and using the aerodynamic loads as inputs to a CAE simulation. The details of the methodology are presented along with results and correlation to experimental data from the wind tunnel. |
Evaluation of Energy Efficiency Performance of Refrigerated and Heated Van Semitrailers | The objective of this project was to provide pertinent information on the performance of refrigeration and heating transportation units to help fleets make decisions that will improve efficiency and increase productivity. To achieve this objective, tests were designed to measure the performance of selected refrigeration and heating units, mounted on refrigerated and heated van semitrailers. Cooling and freezing tests were carried out in summer conditions while heating tests were carried out in winter conditions, for various temperature settings. Two fundamental approaches were considered: the design of the refrigerated or heated trailer and the temperature setting of the refrigeration or heating unit. For cooling and freezing tests, the fuel consumption comparison between similar trailer models of different ages showed that newer units performed better than older ones. However, other factors such as trailer design, presence of a ventilation system, and type of insulation may also influence fuel consumption of such units. For refrigerated trailers of the same make and of similar age, those with swing doors performed better than those with roll-up doors with regards to both fuel consumption and insulation. For trailers with the same make of refrigeration unit, those without side doors performed better than those with side doors. For heating tests, it was observed that newer heated trailers with composite or insulated doors generally consumed 1.5 to 3 times less fuel then the older trailers with wood or metal doors. The tests confirmed that the interior temperature setting has a significant impact on the fuel consumption of the refrigeration or heating unit when the difference in set temperature is considerable. |
Effect of Hinge Axis Inclination and Hinge Tolerance on Door Strength under Abuse Loads | As revealed from J. D. Power surveys, today most vehicle owners consider perceived quality as a direct indicator of the vehicle build quality and durability. [5] The problem has become more prominent and noticeable in recent times, due to the desire for reduced cost, reduced weight targets, aesthetic demands, and crash requirements. The performance of the door assembly when subjected to an abuse load of sag and over opening is one such perceived quality indicator which gives the customer the first impression about the engineering and build quality of the vehicle. Door hinge inclination and hinge contact flushness tolerance are the major design parameters affecting this performance. Although these are an important design parameter, the precise quantification of the effect of these design parameters on door performance under abuse loading has remained somewhat elusive. Traditionally, this assessment was done using physical testing, thumb rules and best practices rather than using computer aided techniques. However with the automotive industry moving towards higher durability targets, reduced product cycle time and lower design costs, the need for virtual simulation has increased. The scope of this paper includes, study of load distribution on the top and bottom hinge pair of the door under over opening abuse load due to hinge contact flushness tolerance and the effect of change in door axis inclination on the door performance under door sag abuse loading. The Finite Element Modelling (FEM) techniques, boundary conditions and the interpretation of the changes in design parameters on the door assembly performance under sag and over opening loading are detailed in the subsequent discussion. |
Magna?셲 New Ultralight Door - A Comparative LCA Study of the Lightweight Design as per ISO 14040/44 LCA Standards and CSA Group LCA Guidance Document for Auto Parts | In response to ever more challenging global fuel economy and environmental regulations, automakers will rely on lightweighting to continue to meet the established goals. As ?쐀olt-on??subassemblies, closure panels provide a unique opportunity to tailor the vehicle mass to achieve local environmental compliance relative to a global vehicle platform while maintaining equivalent functionality and safety performance. This paper is aimed at communicating the results of a life cycle assessment (LCA) study which compares the lightweight auto parts of the new Magna?셲 Ultralight Door design to the conventional auto parts of the baseline 2016 MY Chrysler 200C 6 cyl, 3.6 L, automatic 9-spd, an ICE vehicle (gasoline fueled) built and driven for 250,000 km in North America (NA) [1]. Magna International Inc. (Magna), in cooperation with the United States Department of Energy (U.S. DOE) and partners FCA US LLC (FCA US) and Grupo Antolin, developed a new ultralight door architecture in 2017 that achieved around 40% overall mass reduction compared to the baseline door. Magna?셲 Ultralight door LCA study is conducted in accordance with International Organization for Standardization (ISO) standards 14040/44 and follow the specific rules and guidance provided in the CSA Group 2014 LCA Guidance document for auto parts [2, 3, 4]. |
Optimal Study on the TL of Automotive Door Sealing System Based on the Interior Speech Intelligibility | Wind noise becomes the foremost noise source when a car runs at high speeds. High frequency characteristics of wind noise source and effective performance of seal rubbers for insulating leakage noise make research on the Transmission Loss (TL) of automotive door sealing systems significant. The improvement of TL of automotive door sealing system could effectively decrease the interior noise due to wind noise for vehicles at high speeds. In this study, compression simulation of seal rubbers for an automotive door is performed through a Finite Element (FE) tool firstly. Compressed geometries of the seal rubbers are obtained. Then, based on the final compressed geometries and pre-stress modes of the automotive door seal rubbers, the TL of the whole door sealing system is acquired by hybrid Finite Element - Statistic Energy Analysis (FE-SEA) method. The fluctuating surface pressure on a car body was captured by a Computational Fluid Dynamics (CFD) tool. The wind noise source is obtained by the Corcos model and the Boundary Element Method (BEM). A full vehicle SEA model is built to predict the interior sound pressure level. The TL of the automotive door sealing system is included in the full vehicle SEA model. After the SPL in the car is obtained by SEA simulation, the Articulation Index (AI) is calculated. Finally, the TL of the automotive door sealing system is optimized by orthogonal design of experiment based on AI. This integrated approach can be used to optimize TLs of automotive door sealing systems. |
Research on Stick & Sprag-Slip Phenomenon of Door Waist Belts | The squeak noise generated during the moving of the door glass has a influence on the performance of vehicles felt by the consumer. In order to improve the noise, it is necessary to understand the principle of a friction vibration. In this paper, it is confirmed that the principle on the waist belt is most closely related to stick-slip and sprag-slip among various vibration characteristics. Stick-slip is expressed by energy accumulation and divergence due to difference in static and dynamic friction coefficient. Sprag-slip define instability of geometric structure due to angle of lips on the belt. In this paper, the physical model and the energy equation are established for the above two phenomena. Stick-slip can be solved by decreasing the difference of the static and dynamic friction coefficient. Sprag-slip is caused by the ratio of compressive and shear stiffness of the lips. The belt uses flocking to ensure durability, not coating. Therefore five factors that can be considered in the production of flocking are selected such as thickness. This study introduces an approach to improve the noise using DFSS. To predict the sprag-slip, the lips was modeled by a spring-damper system, and the stiffness value could be derived by applying shear deformation after compression load. The shapes of the lips were designed with 18 cases and the guide for the optimum was provided. It is found that positional deviation occurs due to the equilibrium of forces rather than merely by the tolerance when the glass of the vehicles can be moved from 0 to 2.6 mm. The optimization was confirmed that no squeak noise occurred even under the condition of 3 mm. |
Bumper on Striker: Improve Customer Perception Regarding Door Closing Sound Quality | Did you had opportunity to hear any unpleasant noise when closing some vehicle door? In some cases reminds a metallic touch condition, in other cases reminds several components loose inside the door. The fact is that this kind of noise is definitely unpleasant to the human ears. The good news is that this undesirable condition can be solved easily through of add a soft bumper in the striker; however, needs to pay attention in the material properties and tolerance stack-up conditions to avoid generate side effect, like as high door closing efforts, break parts, lose parts, etc. |
Drivmatic짰 Automatic Fastening System with Single Robot Positioner | The focus of this technical paper is a unique automatic fastening system configuration for loading, positioning & unloading pre-tacked door assemblies within a static C-Frame Drivmatic짰 fastening machine using an off-the-shelf, high accuracy Fanuc robot. In 2011, PMC was awarded a significant contract for supplying commercial OEM aircraft doors and recognized automation was the most feasible approach for fastening each door assembly. At the time of contract award, PMC was an established aero structure supplier with significant automation capability for machining high tolerance parts & assemblies and manual fastening resources to support many different OEM programs however PMC did not have automatic fastening experience or capability. In support of this new Tier-2 contract, PMC reached out to Gemcor to propose a collaborative robot solution for automatically fastening 5 different door assemblies that were historically fastened using a semi-automatic configuration. Demand for quality rivet & Hi-lok installation, preventing rework, fast throughput and avoiding a foundation paved the way for Gemcor to develop a lean approach for fastening some of the most challenging and labor intensive aero structure assemblies. |
Ultra-Light Weight Automotive Door: Design and Validation | An Ultra-Light Door (ULD) has been developed that is 40% lighter than a baseline 2016 mid-size vehicle?셲 driver side door. The ULD scope encompasses the entire door, including the door-in-white (DIW), interior trim, glazing, hardware, wiring, etc. To achieve such a substantial mass reduction while still meeting the baseline vehicle?셲 performance metrics (including safety, durability, NVH, appearance, etc.) at a minimal cost increase, the door design relies on a comprehensive full system approach that includes a unique architecture in addition to lightweight materials and components. This paper details the ULD design concept, simulated performance results, the current status of vehicle level validation, and comparisons between component level CAE predicted performance and physical test results. |
Numerical Simulation Research on Pressure during Door Closure of Commercial Vehicle | The magnitude of door closing force is important in vehicle NVH characters, and in most case, it is not fully studied by computer aided engineering (CAE) in an early developing stage. The research took a heavy-duty truck as the study object and used Computational Fluid Dynamic (CFD) method with dynamic mesh to analyze the flow field of the cabin during door closing process. The change trend of pressure with time was obtained, and the influence of different factors was studied. The experiments were conducted to verify the results. Results show that the velocity of closing door and the size of relief holes have a significant influence on cabin interior pressure, and greater velocity leads to larger the pressure in cabin. The initial angle of the door affects interior pressure less comparing with the velocity of closing door. The interior pressure could be reduced effectively with the method of decreasing the velocity of closing door and increasing the size of relief holes. |
Using Air Walls for the Reduction of Open-Door Heat Losses in Buses | A vital contribution for the development of an environmental friendly society is improved energy efficiency in public transport systems. Increased electrification of these systems is essential to achieve the high objectives stated. Since the operating range of an electrical vehicle is heavily influenced of the available energy, which primarily is used for propulsion and thermal passenger comfort, all heat losses in the vehicle systems must be minimized. Especially for urban buses, the unwanted heat losses through open doors while passengers are boarding, have to be controlled. These energy fluxes are due to the large temperature gradients generated between in- and outdoor conditions and to install air-walls in the door opening areas have turned out to be a promising technical solution. Based on air-wall technologies used for climate control in buildings, this paper presents an experimental investigation on the reduction of heat losses in the door opening of urban buses. Devices for creating the air-wall were located on top of the door opening of an articulated bus of Dresden public transport service DVB AG. Measurements of temperatures were conducted using distributed NTC-sensors. An extensive measuring program was performed and it was found that the air walls had a significant influence on the energy exchange process. On a short door opening time the energy losses increased, while for longer door opening times major reduction on the energy losses were achieved. |
AUTOMOTIVE DOOR CLOSING EFFORTS STUDY | The door is the first system to interact with the customer, allowing the entrance into the vehicle, so it has been given great importance to its performance in all requirements. The automotive door related phenomena studies increased in the past years, once the customer and the market itself have changed their quality standards. The door closing effort is considered a quality issue by the customer, cases it is too high it contributes to quality decrease, based on ergonomics study, each OEM specifies to each vehicle an acceptable value for the closing effort. There is software that uses the finite element method and specific calculation plans for the door closing effort at project phase, but it is necessary lots of data usually not available for the engineer at concept phases. This study's objective is to measure each component contribution in door closing effort with the use of a simplified plan in order to help the product engineer in the door concept phases. Also to help on decisions related to the door Design concept early in the development, minimizing the impacts from possible required changes in later project phases. From a simplified model this plan was made and the output of it was compared to simulations of complex models (CAE). The proposed model has acceptable error, when compared to CAE models, showing the simplifications made were made using criteria in order to impact the less possible in the door closing effort value. |
A Case Study: Application of Analytical and Numerical Techniques to Squeak and Rattle Analysis of a Door Assembly | Squeak and rattle (S&R) problems in body structure and trim parts have become serious issues for automakers because of their influence on the initial quality perception of consumers. In this study, various CAE and experimental methods developed by Hyundai Motors for squeak and rattle analysis of door systems are reported. Friction-induced vibration and noise generation mechanisms of a door system are studied by an intelligent combination of experimental and numerical methods. It is shown that the effect of degradation of plastics used in door trims can be estimated by a numerical model using the properties obtained experimentally. Effects of changes in material properties such as Young's modulus and loss factor due to the material degradation as well as statistical variations are predicted for several door system configurations. As a new concept, the rattle and squeak index is proposed, which can be used to guide the design. The predicted S&R of the door system from the CAE process were compared with experimental results. Practical applications of the developed process and possible future directions of CAE based S&R analysis are discussed. |
A CAE Study on Side Doors Inner Panel Deflection under Glass Stall Up Forces | Not only well-functioning, but also the way operating everyday items "feel", gauges costumer perception of an automobile robustness. To prevent costumer dissatisfaction with door trim panel movement when operating power windows, deflections must be kept small. Deflections of inner panel are seen through trim panel and are responsible for giving a flimsy idea of the door. In this paper, inner panel movement for a fully stamped door in full glass stall up position is analyzed. Through CAE analyses, inner panel behavior was compared, considering different types of reinforcement for belt region. |
Comparative Dynamic Analysis of Sliding Door Based on LS-Dyna and ADAMS | Nowadays, the design and development of the sliding door has been gained great attention for its easy egress and ingress. However, most studies on the kinematic and dynamic characteristics of sliding doors were based on the commercial code ADAMS, while the accuracy of flexibility in modal synthesis method and the ability of complex contact condition may not be guaranteed. Thus, a new dynamic analysis method by using the commercial code LS-Dyna was proposed in this paper to take into account the complex deformation and boundary conditions based on the finite element model. The impact force obtained from the Ls-dyna was compared with that from ADAMS when their monitoring points speed and closing time maintained the same during the sliding process. The impact force between the rollers and the guides was employed as evaluation criterion for different methods because of its effect on the roller wear and the moving smoothness in the sliding process. To validate the results, the impact force was measured by using the strain gauges and optical fibers measure. It turned out that the impact force from LS-Dyna agrees better with the experimental test than that from ADAMS. LS-dyna outperforms ADAMS, in terms of modeling method, dynamic analysis theory and boundary condition. In addition, the dynamic analysis based on finite element method in LS-Dyna environment can simulate the structural deformation and the motion space coupling boundary condition during the sliding process of door better. |
Re-design of Power Sliding Door Pulley System | The power sliding door system(PSD) is being equipped in the MPV(Multi-Purpose Vehicle/minivans) vehicle for convenience in the door operation. This study will focus on package space optimization for interior design and overall vehicle packaging for the vehicles equipped with PSD. To optimize the package, investigation for PSD's structure need to be done and the examples of other vehicle maker will be investigated and compared. The study that considers performance and package requirements resulted in a unique PSD design. And finally, this study will show the result vehicle in which the optimized mechanism is applied. |
Rivet and Bolt Injector with Bomb Bay Ejection Doors | Electroimpact's newest riveting machine features a track-style injector with Bomb Bay Ejection Doors. The Bomb Bay Ejection Doors are a robust way to eject fasteners from track style injector. Track style injectors are commonly used by Electroimpact and others in the industry. Using the Bomb Bay Doors for fastener ejection consists of opening the tracks allowing very solid clearing of an injector when ejecting a fastener translating to a more reliable fastener delivery system. Examples of when fastener ejection is needed are when a fastener is sent backwards, when there are two in the tube, or when a machine operator stops or resets the machine during a fastening cycle. This method allows fasteners to be cleared in nearly every situation when ejecting a fastener is required. Additional feature of Electroimpact's new injection system is integrated anvil tool change. Anvils with fingers are parked on each Injector and an indexing system automatically changes tools for different fastener diameter. Fundamentally, this track-style Injector has only one moving part, the Pusher, used in every fastening cycle. With the Bomb Bay Door ejection system and the integrated automatic tool change, this injection system is very flexible, and is likely one of the fastest in the industry with injection times of under a second. In addition to speed, the new eject system is a robust way to recover from common errors, adding to machine reliability. Overall the new injection system featured on Electroimpact's new riveting machines is a fast, flexible, and robust new system for fastener delivery. |
Challenges Associated with a Complex Compound Curvature Passenger Doors | This study investigates challenges associated with integrating a passenger (PAX) door on complex compound curvature (CCC) fuselages. Aerospace companies are investigating concepts that no-longer have constant cross-section (CS) fuselages. The PAX door is based on a generic semi-plug door for a long range business jet (BJ). This study investigates limitations of locating the door by varying the transition zone angle. A parametric CATIA tool, coupled with the use of finite element model (FEM) results can highlight key drivers in the design and location of PAX doors, creating a first-draft structural layout. The associated impact on the design and structural architecture for a fold down PAX door with integrated stairs is discussed. The impact of CCCs on the PAX door design is investigated with consideration to location, kinematics and function of the door. Design requirements, when coupled with stress analysis to simulate pressurization effect of the load applied to the stops, can create a powerful tool. Combining the architectural layout, design requirements and top-level stress analysis can be used to define limit curves and understand key design drivers that impact the door position, with reference to weight, design and human factor constraints. The design conclusions to-date suggest for a transition angle above 5 degrees, the structure is too complex to use a traditional frame and lintel design and will be an interesting case for bird impact. Below 5 degrees is the limit for conventional door and kinematic designs in-line with frames. |
InCar - Advanced Door Design | The ThyssenKrupp InCar Project is a comprehensive R&D development that gives automotive manufacturers modular solution kits for body, chassis and powertrain applications. The solution kits developed within this project offer weight reduction, cost savings or improved functionality. This paper will focus on the two front door solutions developed within the InCar project. The first door solution, called the Lightweight Door, achieved a 13% weight reduction. This door features a 4-piece tailored blank inner panel and a sandwich material outer panel. The second door solution, called the Advanced Door, is a completely new and innovative door architecture that uses a 2-piece tailored blank mid panel and ultra thin Dual Phase 500 outer panel to achieve an 11% weight reduction. Prototypes were manufactured and tested for both door solutions. This paper will provide a detailed description of everything related to the development of these door solutions, including manufacturing and assembly processes, performance, materials, and cost estimation. |
Study of the Sliding Door Shaking Problem and Optimization Based on the Application of Euler?셲 Spiral | This study focuses on the sudden shaking phenomenon of a sliding door passing through a corner. This phenomenon requires attention because shaking during movement can lead to a harsh operation feeling and a short service life. An experiment based on a test setup was conducted, and the sudden change in the acceleration of a sliding door panel was measured. Based on multi-body dynamics (MBD) analysis and a rigid-flexible coupled model of the sliding door system, the cause of the sudden shaking was determined to be the discontinuous curvature of the middle rail trajectory. A transition curve was proposed as the solution for the discontinuous curvature, and Euler?셲 spiral was applied in the redesign of the middle rail trajectory. Verified by simulations, the results exhibit considerable improvement in sliding door movement stability, with large reductions in the maximum center of mass (CM) acceleration and guide roller impact force. |
Application Study of Blind Spot Monitoring System Realized by Monocular Camera with CNN Depth Cues Extraction Approach | The image from monocular camera is processed to detect depth information of the obstacles viewed by the rearview cameras of vehicle door side. The depth information recognized from a single, two-dimensional image data can be used for the purpose of blind spot area detection. Blind spot detection is contributing to enhance the vehicle safety in scenarios such as lane-change and overtaking driving. In this article the depth cue information is inferred from the feature comparison between two image blocks selected within a single image. Convolutional neural network model trained by deep learning process with good enough accuracy is applied to distinguish if an obstacle is far or near for a specified threshold in the vehicle blind spot area. The application study results are demonstrated by the offline calculations with real traffic image data. |
Utilizing Weathering Effect to Understand Squeak Risk on Material Ageing | Squeak and rattle concerns accounts for approximately 10% of overall vehicle Things Gone Wrong (TGW) and are major quality concern for automotive OEM?셲. Objectionable door noises such as squeak and rattle are among the top 10 IQS concerns under any OEM nameplate. Customers perceive Squeak and rattle noises inside a cabin as a major negative indicator of vehicle build quality and durability. Door squeak and rattle issues not only affects customer satisfaction index, but also increase warranty cost to OEM significantly. Especially, issues related to door, irritate customers due to material incompatibilities. Squeaks are friction-induced noises generated by stick-slip phenomenon between interfacing surfaces. Several factors, such as material property, friction coefficient, relative velocity, temperature, and humidity, are involved in squeak noise causes. For example, door armrest leather is exposed longer to sunlight and when customer places his hand on the armrest, an annoying squeak noise is generated due to permanent or temporary weathering effect. In this study, an experimental work is conducted to investigate squeak performance of door trim materials against weather ageing effect. As per the standard SAE-J2412, one thousand five hundred hours of polymer weathering test which is considered equivalent to 5 years of product life were performed to door trim material samples. Material compatibility test were performed on door trim samples at different time intervals of 0, 250, 500,750, 1000& 1500 hrs to evaluate its squeak risk behavior. On basis of RPN results, it was found that some material combination failed at 500 and 750 hrs highlighting squeak risk due to weathering effect. This paper introduces a new DVP, where a process can be established for material selection and avoid customer irritants and improve the perceived quality not only for a new vehicle but even after mileage degradation. |
Door Seal Behavior Prediction and Enhancement in Performance Using Digital Simulation | Automotive door seal has an important function which is used extensively where interior of the vehicle is sealed from the environment. Problem with door seal system design will cause water leakage, wind noise, hard opening or closing of doors, gap and flushness issue which impair customer?셲 satisfaction of the vehicle. Moreover, improper design of seal can lead to difficulty in installation of door seal on body panel. The design prudence and manufacturing process are important aspect for the functionality and performance of sealing system. However, the door sealing system involves many design and manufacturing variables. At the early design stage, it is difficult to quantify the effect of each of the multiple design variables. As there are no physical prototypes during rubber profile beading-out stages, engineers need to carry out non-linear numerical simulations that involve complex phenomena as well as static and dynamic loads for door seal. This paper presents a digital simulation design tool based on FEM, basic governing laws and incompressibility constraints. Door seal was analyzed for compression load deflection (CLD) behavior using nonlinear finite element analysis in MSC Marc Mentat?? The analysis results provided some major parameters, such as seal deformation, contact pressure and contact length of seal, which would influence the functionality and performance of the door sealing system. The analysis results have been compared with available test data, and very good correlation was obtained. This analysis also evaluated the influence of manufacturing deviations. This analysis method developed into a tool that is capable of predicting water leakage, wind noise and hard to open/close problems caused by either product design or manufacturing process. |
Sink Butt Welding for 120 Degree Door Frame Design | This paper deals with vehicle door 120-degree joint rust issue and water leak faced in most of SUV cars. Generally based on vehicle segment its styling curves and exterior design are defined. A Sedan or Hatchback is provided with curves to show its fluidic design but a SUV is provided with Straight lines to show its aggressive look. In existing condition door frame Joint has sharp joints where weld bead is added to prevent rust in joint area, but still improper seating of weather strip on weld bead cause water leak. Door?셲 A Pillar Frame and Horizontal Frame match at 120 degree joint edges are chamfered straight to match perfectly. Weld bead runs over the matching profile to join it. But weld bead project over the Frame surface and affects weather strip seating & results in poor sealing. Adhesive added for better sealing also follows the same path on bead and create a path way for water entry. Thus in long run this water stagnates and cause chronic rust issues in frame. This in turn results in high claim cost within warranty period. It is serious issue which should be addressed. This paper investigates deeply the process of eradicating the rust issue and water leak issue simultaneously. Edges of frame are provided with forming at 120 Joint matching areas. So that weld bead gets sink into shallow depth without projecting out from the surface. This flattened profile of weld bead on frame surface results in perfect sealing of weather strip. This is how sink weld prevents rust and arrest water entry. |
Squeak Noise Prediction of a Door Trim Panel Using Harmonic Balance Method | Squeak and rattle noise in a vehicle?셲 interior is perceived as an annoying sound by customers. Since persistent noise (e.g. engine, wind or drive train noise) has been reduced continuously during the last decades, the elimination of sounds, which have their origin in the vehicle?셲 interior components, is getting more important. Therefore, noise prediction based on simulation models is useful, since design changes can be realized at lower costs in early virtual development phases. For this task, linear simulation methods are state of the art for the identification of noise risk, but in general without knowing if a sound is audible or not. First approaches have been developed based on the Harmonic Balance Method to predict squeak noise and assess their audibility. This paper presents vibroacoustic measurements at a door trim panel for squeaking and non-squeaking configurations. Vibrations are excited harmonically by a force controlled low noise shaker. The system response is measured in a semi-anechoic chamber by acceleration sensors and audibility is assessed. Additionally, a 3D finite element model is built and the Harmonic Balance Method using a dry friction law is applied to predict the acoustic behavior. Finally, the simulation results are compared to the measurements. A good agreement between simulation and experiment can be observed. |
Development of a Thin-Wall Magnesium Automotive Door Inner Panel | Cast magnesium (Mg) door inner panels can provide a good combination of weight, functional, manufacturing, and economical requirements. However, several challenges exist including casting technology for thin-wall part design, multi-material incompatibility, and relatively low strength versus steel. A project was supported by the US Department of Energy to design and develop a lightweight frame-under-glass door having a thin-wall, full die-cast, Mg inner panel. This development project is the first of its kind within North America. The 2.0 mm Mg design, through casting process enablers, has satisfactorily met all stiffness and side-impact requirements, with significant mass reduction and part consolidation. In addition, a corrosion mitigation strategy has been established using industry-accepted galvanic isolation methods and coating technologies. The performance of the Mg design has been demonstrated through component and vehicle tests. This article is an updated publication of a previously published International Mg Association (IMA) proceedings paper [1] (with agreement from the Association). |
Damping out booming noise | NVH improvement techniques are gaining traction with the goal to improve the quality perception of off-highway equipment performance and operator comfort. As NVH gains importance in the quality of off-highway machine performance and operator comfort, it is essential to understand every aspect of the machine noise and its annoyance effect on the operator, then reduce the noise to a level that does not affect comfort and performance. Booming noise-a low-frequency NVH phenomenon below 200 Hz often described as a continuous bass drum roll, distant thunder sound, or a deep resonant sound like an explosion-is a major concern in off-highway machines. The booming noise in off-highway machines can be caused by a combination of factors: the low natural frequencies and damping of the large panels of machine cabs; the low acoustic modes of the cab cavity; low-frequency excitation into the cab from machine noise sources such as engine, exhaust, cooling fan, etc.; and low frequency excitation to the machines from machine work tools and ground interaction inputs (tire lug, road profile, etc.). |
Recent Advances in Powertrain Sound Quality Hardware Tuning Devices and Perspectives on Future Advances | Over the past decade there have been significant advances made in the technology used to engineer Powertrain Sound Quality into automobiles. These have included exhaust system technologies incorporating active and semi-active valves, intake system technologies involving passive and direct feedback devices, and technologies aimed at tuning the structure-borne content of vehicle interior sound. All of these technologies have been deployed to complement the traditional control of NVH issues through the enhancement of Powertrain Sound Quality. The aim of this paper is to provide an historical review of the recent industry-wide advances made in these technologies and to provide the author's perspective on what issues have been addressed and what opportunities have been delivered. The paper will offer the author's perspective on how these existing Sound Quality hardware tuning technologies have evolved, how they will continue to evolve, what new technologies are showing potential, and how they will have an increasingly significant contribution to make in the medium and long term future of Vehicle NVH and Sound Quality development. |
Applications of the Statistical Energy Analysis to Vibro-Acoustic Modeling of Vehicles | In recent years, SEA has been recognized as an important tool to model the vibro-acoustic behavior of vehicles in mid and high frequencies. Through SEA it is possible to develop vehicle models early in the design stage, reducing the risk of future noise problems and allowing the optimization of noise control treatments. Moreover, at the final design stages, a SEA model can be use to evaluate changes at the project, reducing costs with experiments. In a SEA model, the structure under study is divided in subsystems. The capacity of each subsystem of storekeeping, dissipating and transmitting energy is described by three parameters: modal density, loss factor and coupling loss factor. The noise and vibration sources are include in the model as power inputs to subsystem and, based on an equilibrium power balance, it is possible to calculate the energy of each subsystem. The results obtained by SEA models should be interpreted as average values in time, in the frequency band, in space and at an ensemble of random structures. In this work, the applications of SEA at the vibro-acoustic modeling of vehicles are discussed. The details that should be observed when defining the structural and acoustic subsystem are pointed out. The main methods for the determinations of the SEA parameters are introduced. Special emphasis is given to the calculation of the power inputs of the main noise and vibration sources in a vehicle. Finally, some practical applications of SEA at the automotive industry are presented and discussed. |
TREASURI: An Innovative Simulation Method for the Vibro-Acoustic Design of Passenger Compartments | 0 The accuracy of nowadays CAE tools for simulation of sound pressure level distributions in the passenger compartment of vehicles is not satisfactory because of the simplify models, especially with regard to the description of common passive acoustical treatments. This report describes the application of the TREASURI method on a complete vehicle, equipped with sound deadening treatment sound absorbing material sound insulation treatment and interior trim material (e.g. instrument panel, seats, center console). In order to validate the method, the simulation results were compared with the measurement results from the corresponding vehicle. The evaluation shows that the TREASURI approach yields considerable improvements in simulation accuracy up to 300 Hz compared to classical approaches [1]. This method now enables reliable predictions of acoustical influence on structural modifications and changes of the sound package. |
Visualization of Sound Field in Automobile Cabin using Sound Intensity Technique | For examining sound field in automobile cabin, it is important to visualize a noise source and it's behavior. This paper reports the results of visualized sound field using measurement data of sound intensity analysis. In general, it is difficult to obtain an appropriate result for source localization in reflective sound field where normal mode can be occurred with sound intensity analysis. We tried to distribute many receiving points and examined noise source localization in automobile cabin with this technique and found it effective. After the treatment of sound insulation, we found that measurement results reveals difference with and without countermeasure. |
Real-Time Pass-by Noise Source Identification Using A Beam-Forming Approach | Noise source identification is becoming a key issue in the dimensioning and troubleshooting steps of the design process. In the automotive industry, OEM's and suppliers need to assess the entire description of vehicle noise emission, both for interior comfort and exterior radiation concerns. The resolution of pass-by noise issues pose one of the most significant problems to vehicle designers. While many commercially available systems allow the evaluation of the overall noise emission at any speed and position during the test the task of identifying specific sources is still mainly performed using component masking. A new measurement technique has been developed using a microphone array (typically 2m 횞 2m with 64 transducers or more) and acoustic beamforming techniques that allows visual source identification at any point during the test. Typically, the entire side of a vehicle can be evaluated with one single measurement run. This paper describes the method employed and presents results obtained from a high-speed pass-by test on a minivan. |
Development of a Hybrid SEA Modeling Scheme for a Passenger Car | A hybrid SEA modeling scheme has been developed and applied to obtain an accurate SEA model for a passenger car. In this study, the detailed workflow associated with the hybrid SEA modeling scheme will be described. Each step in the workflow will be discussed in terms of the obtained data, the corresponding analysis and results. In those steps, several innovative methods for developing the hybrid SEA model will be presented. Finally, a road noise analysis will be performed using the hybrid SEA model to validate the SEA model for the passenger car. In order to demonstrate the accuracy of the model, the analysis results such as the sound pressure level of car interior will be compared with the measurements. |
Development of a Parametric Blend Door Computer-Aided Design System | This paper describes the development of an analytical tool for the design automation of the temperature blend door mechanism in an automotive HVAC system. The function of the blend door is to control the temperature of the air blown into the cabin interior by regulating the mix of air passing through the heater core. The objective in the design process is to achieve a prescribed function of temperature with respect to control position at the instrument panel. The control effort to effect the desired temperature change is also another important consideration for customer satisfaction. The current design process is empirical in nature and relies on laboratory and vehicle testing with prototypes. The process is also iterative in nature and may continue until the end of the overall design cycle of the complete air handling subsystem. A parametric feature-based computer model, described subsequently in detail, allows for virtual prototyping of the blend door control mechanism. With this model, various blend door designs can be explored early in the design cycle. Late changes required for packaging can also quickly be analyzed. Kinematic analysis of the blend door mechanism allows the control curve and control effort to be predictive. This desktop simulation tool will enable designs to be optimized or permit the number of options to be narrowed, which will reduce test time and shorten design cycle time. Illustration of the desktop tool is based upon predicting control curves and efforts for a production HVAC system. Also, airflow and temperature data from CFD analysis for this production system is presented. Finally, predicted results are compared and correlated with actual laboratory and vehicle test data. |
Development of a Film Door Type Air Conditioning Unit | Recently, an increasing demand for comfort has been accelerating the trend toward multifunctional car air conditioners, including zone air conditioning which controls the cabin temperature independently for the driver and the passenger and compensates for the side solar radiation. In addition, the multifunctional air conditioner should be compact to save cabin space and ensure passenger comfort. This report describes the development of a compact and multifunctional car air conditioning unit. |
Design and Development of Automatically Deployed Entry Steps for a Fire Truck Cab | An automatically deployed fold-down step has been developed for use on fire apparatus cabs. The step operates pneumatically as the cab doors are opened. This feature optimizes the ergonomics of cab entry while maximizing the interior space available for occupants and equipment. |
Measures to Quantify the Sharpness of Vehicle Closure Sounds | Impulsive sound events (i.e. door closing) are often characterized as being undesirably sharp sounding. A high degree of perceived sharpness is normally related to large amounts of high frequency energy relative to the low frequency energy. In this project third octave data generated from a filterbank was used to calculate the center of gravity (cg) of the third octave bands. The result is the frequency corresponding to the centroid of the third octave data. Sounds with substantial high frequency energy have a centroid location that occurs at a higher frequency. The mean of the third octave cg over the duration of the transient event was investigated, in addition to sharpness as defined by Aures [1] and calculated on a commercially available analyzer. Correlation analyses to subjective data indicate that the mean third octave cg and the commercially available method produce comparable results for the vehicle closure sounds studied here. Sounds with more high frequency energy during the Initial impact were sharper, while sounds with substantial low frequency energy following the impact were less sharp. |
Extended Cab Side Access Panels - Compact Pick-Up Trucks | In the past, all known, compact pickup truck structures have been limited to the use of two doors to allow for access to the interior regions of the cab. This paper will address the issue of locating a side access panel to an existing vehicle structure, the development criteria used for the panel hinges, the integration of the safety belt system and the advantages of the interior trim attachment methods. Examination will include a review of specific design considerations used to meet governmental and consumer requirements. |
POGO??Flexible Tooling Universal Holding Fixture for Cutting, Drilling and Assembly in the Aerospace Industry | The aerospace industry has entered a new level of World Class Manufacturing, in which manufacturing functions require fixturing to be just as flexible as the machine tool doing the operation. Flexible tooling has opened new doors for the aerospace industry by creating new tools which are automatically reconfigurable and totally reusable on future programs. Benefits include decreases in non-recurring costs, (such as in the area of tool design and fabrication) and recurring costs, (such as in the area of tool setup / removal and storage). |
Improving Recyclability Through Planned Product Revisions | Whether propelled by a concern for the environment, increasingly stiff legislation, or higher disposal costs, companies are trying to reduce the environmental impacts of their products. At the same time, designers are forced to balance the need to get a product out the door with the desire to improve the product's functionality. Candidate designs are often so constrained that addressing environmental goals proves impossible. In this paper, we discuss the improvement of recyclability for vehicle assemblies through a process of planned design changes over multiple revisions of the product. Specifically, we present the results of a case study describing the creation of a strategy for focusing the recyclability improvement effort to a generic instrument panel (I/P). The possible improvement in recyclability is examined as well as the impact on other design characteristics as the limiting factors for the instrument panel are chosen. Based on this analysis, a plan for focusing the design effort to improve vehicle recyclability is provided. |
Application of a Laser Vibrometer for Automotive Aeroacoustic Analysis | The Scanning Laser Vibrometer can make full field, high resolution measurements of the normal surface velocity of automotive door glass and sheet metal vibrations. These properties make the vibrometer a very useful tool for locating compliant and noisy areas on the surface of a vehicle, generated by exterior wind noise. An advantage of the vibrometer is that it measures the vibration of the surface, capturing the transfer of noise through the surface, rather than simply measuring the exterior wind noise. Methods of experimental setup, testing, and problem analysis on outside rear view mirror/A-pillar/Sideglass configurations and body panel vibrations are discussed in the paper. |
Optimizing Parts and Systems Integration with Engineering Thermoplastics to Meet the Challenges of Future Automotive Door Systems | As automakers struggle to meet often conflicting safety, weight, styling, and performance requirements, engineering thermoplastics (ETPs) are making increasing inroads into applications that once were the exclusive domain of metals, glass, and thermosets. A good example of this is in the door systems area, where the performance, design flexibility, aesthetics, parts integration, and lower specific gravity offered by ETPs are allowing highly integrated and efficient modules to be created that, in turn, increase assembly efficiency and reduce mass, part count, warranty issues, and systems costs. This paper will use several case studies on innovative door hardware modules and door panels to illustrate the advantages offered by this versatile class of engineering materials. |
Development of a Sled-to-Sled Subsystem Side Impact Test Methodology | A sled-to-sled subsystem side impact test methodology has been developed by using two sleds at the WSU Bioengineering Center in order to simulate a car-to-car side impact, particularly in regards to the door velocity profile. Initially this study concentrated on tailoring door pulse to match the inner door velocity profile from FMVSS 214 full-scale dynamic side impact tests. This test device simulates a pulse quite similar to a typical door velocity of a full size car in a dynamic side impact test. Using the newly developed side impact test device three runs with a SID dummy were performed to study the effects of door padding and spacing in a real side impact situation. This paper describes the test methodology to simulate door intrusion velocity profiles in side impact and discusses SID dummy test results for different padding conditions. |
Experimental Assessment of Wind Noise Contributors to Interior Noise | Wind noise reaches the interior of a vehicle through a variety of mechanisms including: aerodynamic excitation of vibration and reradiation from the greenhouse surfaces; acoustic transmission through door seals including gaps and glass edge leaks, and due to airborne transmission of noise generated by wind interaction with body panels. This paper presents experimental results that quantify contributions to interior noise from individual greenhouse surfaces and from airborne sources on the underbody. The measurements were carried out on a production vehicle in a wind tunnel. Greenhouse surfaces, in addition to the driver window are important contributors to interior noise along with airborne transmission of noise generated due to the flow over and through the vehicle underbody. |
Sound Transmission Through Primary Bulb Rubber Sealing Systems | Structural sound transmission through primary bulb (PB) sealing systems was investigated. A two-degrees-of-freedom analytical model was developed to predict the sound transmission characteristics of a PB seal assembly. Detailed sound transmission measurements were made for two different random excitations: acoustic and aerodynamic. A reverberation room method was first used, whereby a seal sample installed within a test fixture was excited by a diffuse sound field. A quiet flow facility was then used to create aerodynamic pressure fluctuations which acted as the excitation. The space-averaged input pressure within the pseudo door gap cavity and the sound pressure transmitted on the quiescent side of the seal were obtained in each case for different cavity dimensions, seal compression, and seal designs. The sound transmission predictions obtained from the lumped element model were found to be in reasonable agreement with measured values. The measured noise reduction was found to be very similar for both types of excitation. This confirmed that an acoustic excitation may be used instead of aerodynamic pressure fluctuations for sound transmission measurements, and that the barrier performance of the PB seal was not significantly affected by the presence of a static pressure gradient associated with the mean flow. The wind tunnel method was also found to yield a better signal-to-noise ratio than the reverberation room method. |
Static and Dynamic Dent Resistance Performance of Automotive Steel Body Panels | In recent years, strict weight reduction targets have pushed auto manufacturers to use lighter gauge sheet steels in all areas of the vehicle including exterior body panels. As sheet metal thicknesses are reduced, dentability of body panels becomes of increasing concern. Thus, the goal becomes one of reducing sheet metal thickness while maintaining acceptable dent resistance. Most prior work in this area has focused on quasi-static loading conditions. In this study, both quasi-static and dynamic dent tests are evaluated. Fully assembled doors made from mild, medium strength bake hardenable and non-bake hardenable steels are examined. The quasi-static dent test is run at a test speed of 0.1 m/minute while the dynamic dent test is run at a test speed of 26.8 m/minute. Dynamic dent testing is of interest because it more closely approximates real life denting conditions such as in-plant handling and transit damage, and parking lot damage from car door and shopping cart impact. The dent resistance performance of the three steel types are examined and compared for both static and dynamic test conditions. |
DEVELOPMENT OF A UNIQUE, GAS-INJECTION MOLDED DOOR HARDWARE MODULE FRAME | A unique design, engineering, and manufacturing approach has been used to create the first all-plastic door hardware module frame. The result of many years of intensive development efforts by a team of companies, the gas-assist injection molded frame features a high degree of parts consolidation and has been critically acclaimed as ?쐔he first major metal-replacement automotive part since the bumper, a quantum leap in injection molding complexity, and the biggest commercial breakthrough ever in gas assist molding [1].??The program also proved to be an excellent example of the types of technological breakthroughs that can come from concurrent engineering and strategic partnering. This paper will provide an overview of the component's development, describe the many challenges facing the team, and share solutions that contributed to the success of the program. It will also illustrate the benefits of successfully implementing a design and production strategy that carefully matches design, materials, tooling, and processing. |
Automotive Body Component Field Corrosion Behavior in the De-Icing Salt Zone | Doors were removed from recycle-yard vehicles in Syracuse, N. Y. and examined in the laboratory as part of an on-going field study on corrosion behavior trends in the de-icing salt region of the U. S. Lower doors, including hem-flange internal surfaces, were examined, and performance trends as a function of materials selection, age and mileage were determined. The results to date on doors from 167 Syracuse vehicles are indicative of the nature and history of salt-induced corrosion in the region, and they indicate the degree of benefit from galvanized construction and body design features. |
Material Options for Automotive Interior Trim | This paper outlines the relationship between airbag door choices and instrument panel coverstock materials which are being used in the global automotive market for passenger vehicles as well as those materials that are being considered for use in future vehicles. The introduction of an invisible airbag door into the instrument panel is changing the material and testing requirements as safety and reliability are now key considerations. Increasing material options are available to meet these requirements. In this paper, we review the material options, processing methods available, advantages/disadvantages of each, and the current market status of the different materials. |
Design and Development of a Magnesium/Aluminum Door Frame | This paper describes the methodology by which a combination die cast magnesium and extruded aluminum door frame was developed using a current production steel door design as the base model for comparison. Product performance data, such as side impact requirements and overall door stiffness, along with the packaging of existing internal hardware, is presented. The results are verified by computer modeling. A prototype casting was produced to validate and compare castability requirements and geometry constraints of the door frame. An economic study is included that investigates the potential of developing such a system suitable for production. The results suggest that economic benefits may be obtained by using such a lightweight door system compared to an existing steel door design. |
Measurement of Airborne Noise Reduction of Production Door Components on a Buck | Various automobile door components were evaluated for air-borne noise reduction using production and prototype door assemblies which were modified to fit an SAE J-1400 test fixture. The in-door laboratory evaluation provided a single noise reduction rating in decibels for diverse door assembly components, with different noise reduction mechanisms. This test method overcame some of the shortcomings associated with evaluating each component individually in accordance with an acoustical material test standard. |
Nd:YAG Laser Welding for Automotive Manufacturing Applications | The power output of commercially available continuous wave (CW) Nd:YAG lasers has increased substantially over the last few years. Models which can deliver 4 kW to the workpiece are now available. At this power level, the Nd:YAG laser can effectively compete with the CO2 laser in many laser welding applications. The easier, fibre optic based, beam delivery of the high power Nd:YAG laser makes a number of applications possible which were considered impractical using CO2 laser technology. This paper will first describe the general characteristics of an Nd:YAG laser system as configured for welding, and contrast these features with a typical CO2 laser welding system. Points of discussion include: laser power, beam delivery options, focus spot characteristics including the capabilities of twin spot beam delivery with an Nd:YAG laser, and the interaction of the laser beam with the metal surface, including a brief description of the laser generated plasma. Some specific configurations for an Nd:YAG laser-based weld cell will then be described. In the second section, a number of applications for Nd:YAG laser welding will be described, and sample parts and weld characteristics will be shown. These applications include: welding of tailored blanks for body stampings using 1D and 2D weld geometries, welding of reinforcing patches onto blanks for shock towers, laser welding of hemmed door and hood joints, laser welding of tailored tubes for hydroforming, laser welding of aluminum panels, and laser welding for auto body assembly. The Nd:YAG laser is not expected to replace the CO2 laser completely, but there are a number of applications which are better suited to laser welding with an Nd:YAG than a CO2 laser. The ability to deliver the laser power to the workpiece through a flexible fibre also opens new laser welding applications, and creates more competition for traditional joining techniques. |
Intelligent Audio Amplifier | An intelligent amplifier has been developed which delivers output power to either a two or four speaker audio system. The amplifier determines the number of speakers present during the start-up sequence and configures itself either as two BTL amplifiers or four single ended amplifiers. The system does not require any wiring modifications to operate in either mode and will reconfigure itself on each start-up cycle allowing system modifications, such as adding speakers, without additional wiring or hardware modifications. Difficulties arise when determining the presence of speakers in an automotive environment. Extraneous noise sources such as door slams, hatch slams and engine cranking can cause erroneous measurements thus inappropriate configurations. The presented circuit was determined to be immune to these noise sources and is based upon: 1. Integration of measurements over a fixed period of time 2. Applying a large voltage to overcome noise sources without creating audible disturbances 3. Fixed switch on behavior |
Concept to Production: Continuous Surface Keypad Switch | The objective of this paper is to impart the challenges presented and the solutions derived to transform an artist's rendering into a production driver's door switch to be used in the interior of a high profile sports car. The challenges took many forms throughout the process, from data translation and packaging, to the final decorative issues. The results are a finished product providing a new approach to automotive interior switch design. It incorporates a low profile, continuous plane keypad with ?쐓oft touch??feel, tactile feedback, and integrated back lighting. |
Optimized Radii for Draw Dies | This paper deals with the radii of draw dies for sheet metal parts, like fenders, hoods, and doors. For relative flat parts, like hoods, it is important to get at least a 2% forming rate in the middle of the part to reach minimum of stiffness, work hardening, and sufficient geometric accuracy. This can be influenced by the punch radii. Therefore, optimal punch radii should be known. First experimental results about optimal punch radii where published by J.L. Duncan and B.S. Shabel in the SAE-Paper No. 780391. At the Institute for Metal Forming Technology of the University of Stuttgart, Germany, a ?쏮odified Duncan Shabel Test??(MDS-Test) has been developed. This test makes it possible to investigate not only the punch radii but also the die radii. This paper shows optimal punch and die radii as a function of sheet metal, sheet thickness, as well as of the die material. |
High Mileage Squeak and Rattle Robustness Assessment for Super Duty Cab Weight Reduction Using High Strength Steel and Adhesive Bonding | Squeak and rattle is one of the major concerns in vehicle design for customer satisfaction. Traditionally, squeak and rattle problems are found and fixed at a very late design stage due to lack of up-front CAE prevention and prediction tools. An earlier research work conducted at Ford reveals a correlation between the vehicle overall squeak and rattle performance and the diagonal distortions of body closure openings under a static torsional load. This finding makes it possible to assess squeak and rattle performance implications between different body designs using body-in-prime (B-I-P) and vehicle low frequency noise vibration and harshness (NVH) CAE models at a very early design stage. This paper presents an application of this squeak and rattle assessment method for a design feasibility study concerning a cab structure of a super duty truck for weight reduction using high strength steel and adhesive bonding. The study indicates that downgaging and substitution of mild steel with high strength steel combined with adhesive bonding in selected areas of a cab structure can achieve 12.7 Kg (4% of B-I-P) weight reduction without tooling changes while maintaining high mileage squeak and rattle performance of the baseline vehicle. |
High Frequency Effects on Localization and Sound Perception in a Small Acoustic Space | As compared to home audio, the automobile has a different spatial and spectral distribution of sound. This can cause stereo images to blur or shift due to conflicting localization cues. The impact of interaural time and level differences is discussed, along with frequency-selective pinna and head cues. Review of the literature shows that our poorest localization is for mid frequencies (??kHz). Yet in an automobile, low frequencies are severely relocated with a minimum effect on fidelity. It is suggested this is because middle frequencies dominate the perception and localization of sound. Therefore, some high frequency information might also be relocated. |
Prediction of Flow-Induced Noise in Automotive HVAC Systems Using a Combined CFD/CA Approach | Noise emission from automotive HVAC systems has become an important factor for passenger comfort. Consequently, efforts are made during the design phase to minimize noise generation, and to improve sound quality. Predictive tools for the aeroacoustic behavior of components, subsystems and whole systems early on in the design phase are therefore desirable. In this paper a combined Computational Fluid Dynamics (CFD) and Computational Acoustics (CA) approach for the prediction of sound generation and propagation is investigated. Three different experimental setups, ranging from a more academic example to examples relevant in the design process of climate control systems, have been devised to provide test data for the evaluation. Experimental and numerical results are presented and discussed. |
Experimental Investigation of the Response of the Human Lower Limb to the Pedestrian Impact Loading Environment | Three limbs were taken from post mortem human subjects and impacted on the lateral aspect by a free-flying (30 km/h) impactor below the knee joint. Tri-axial MHDs and tri-axial accelerometers were used to determine the kinematics of the limb; strain gages were used to measure surface strain on the tibia and femur; and acoustic sensors were used to identify the onset and timing of injury. This data set was analyzed to compute the response of the knee joint to a bumper impact. Post-test necropsy results showed that the primary injury mechanism in each case was complete avulsion of the Medial Collateral Ligament (MCL) and the Anterior Cruciate Ligament (ACL). |
Geometric Visibility of Mirror Mounted Turn Signals | Turn signals mounted on exterior rearview mirrors are increasingly being used as original equipment on passenger cars and light trucks. The potential for mirror-mounted turn signals (MMTS) to improve the geometric visibility of turn signals is examined in this paper. A survey of U.S. and UN-ECE regulations showed that the turn signals of a vehicle that is minimally compliant with U.S. regulations are not visible to a driver of a nearby vehicle in an adjacent lane. Measurements of mirror location and window geometry were made on 74 passenger cars and light trucks, including 38 vehicles with fender-mounted turn signals (FMTS). These data were combined with data on driver eye locations from two previous studies to assess the relative visibility of MMTS and conventional signals. Simulations were conducted to examine the potential for signals to be obstructed when a driver looks laterally through the passenger-side window. With a vehicle population that is fifty percent light trucks, MMTS are visible 52 percent more often than FMTS in this scenario. Based on the lateral visibility analysis, the optimal height for geometric visibility of a signal in the adjacent-vehicle scenario is 124 cm above the ground, approximately the average height of a light truck mirror. A plan-view eccentricity analysis showed that an MMTS is much closer to the viewing driver?셲 forward-directed line of sight than rear-mounted turn signals when the viewing driver?셲 vehicle is in or near the blind zone between the signaling driver?셲 mirror and direct peripheral fields of view. MMTS can improve the geometric visibility of turn signals in the adjacent-vehicle scenario that is believed to precede many lane-change/merge crashes. Further research will be necessary to determine if improved geometric visibility is accompanied by improved detection of turn signals by viewing drivers, and whether improved detection of turn signals has important safety implications. |
Dynamic Element Analysis | A new formulation for dynamic analysis of the response of vibro-acoustic systems is developed. The method is based on a discrete element formulation similar in geometry to a finite element model. However, the Dynamic Element Analysis uses transcendental functions for the response interpolation functions. The phase of the functions converges at high frequencies to the Statistical Phase. At low frequencies the interpolation functions converge to the polynomials used in finite elements. Thus, the Dynamic Element Analysis covers a wide frequency range without requiring a refinement of the mesh, and it provides a deterministic response in the mid-frequency range before converging to a statistically correct response at high frequencies. Examples are shown of the response of structures and acoustic radiation. |
Lessons Learned Through Working With General Motors | In many companies and corporations, a number of very good ideas never reach fruition, even after a substantial investment in time and money. Can corporations afford to squander such assets?쫛r is it a result many other forces and variables that inadvertently conspire to failure? The Vibration Advisor Expert System is one of these great ideas with a significant amount of time and money invested and a proven functionality that didn't make it. This paper will describe the project and offer for discussion and thought, some of the reasons for implementation failure. It was the right tool at the right time - but it did not benefit the Corporation. |
Measurement of Sound Impulses Due to Airbag Deployment in a Standardized Enclosure | The consistent measurement of airbag deployment noise places special demands on the enclosure in which the measurements are performed. The acoustical characteristics of the enclosure must be stable over long periods. It must also be sufficiently robust to withstand the loads involved. The use of a standardized enclosure provides a uniform basis for comparable measurements in different laboratories. The reasons for selecting a specific small cabin as the standard enclosure are discussed in this paper. Some examples of tests performed in the small cabin with a wide range of airbag systems are presented. High-speed film recordings of the deployment of the airbags were made simultaneously with the acoustic measurements. The stability of the acoustic environment and of the enclosure were important factors in obtaining reliable and comparable results. |
Road Noise Reduction Using a Source Decomposition and Noise Path Analysis | It is considered that improper usage of rubber bushes and weak dynamic characteristics of chassis and body structures yield interior road noise problems. This paper describes systematic processes for road noise improvement along with measurement and analysis process. Firstly, the noise sources are identified by using a source decomposition method. Secondly, the main noise paths are identified by using a noise path analysis (NPA) method. Thirdly, the design modification of body panels is suggested for road noise reduction by using a panel contribution analysis. Finally the method is validated by applying to road noise improvement process for a new vehicle. |
A Study on the Development Process of a Body with High Stiffness | Design optimization of a vehicle is required to increase a product value for noise and vibration performances and for a fuel-efficient car. This paper describes the development process of a high stiffness and lightweight vehicle. A parameter study is carried out at the initial stage of design using the mother car, and a design guide with a good performance is achieved early prior to the development of the proto car. Influences of body stiffness based on the relative weight ratio of the floor and side structures are analyzed. Results show that bending and torsional stiffness has a significant effect on weight distribution ratio. Influences of the distribution of side joint stiffness are analyzed through numerical experiments. Results reveal that the stiffness difference between the upper and lower parts should be small to increase the stiffness of a body. In addition, the process of designing the body attachment stiffness is summarized to ensure the vibration isolation of the suspension mounting unit. In the case of the rear suspension mounting unit, the body attachment stiffness is found to increase in the left and right direction, when the package tray pass-through structure is used on the rear wheel housing and rear floor joint, to minimize rear seat noise. This paper is expected to shorten the development period by the present stiffness analysis process. And a body with high stiffness and lightweight is developed for the vibration and noise performance at the initial stage of design. |
Statistical Energy Analysis of a Fuel Cell Vehicle | In this paper the application of Statistical Energy Analysis (SEA) to the sound package design for a fuel cell powered sedan is presented. Fuel cell vehicles represent a different challenge to a vehicle with a conventional powertrain. With the replacement of the internal combustion engine (ICE), a principal source of airborne and structure-borne powertrain noise, the expectation is that the cabin noise levels would be significantly reduced as the main noise sources would be road and wind noise. A fuel cell powertrain, however, has a number of mechanical sources on the body structure that will radiate airborne noise and may transmit significant structure-borne noise to the vehicle interior. With this alternative power train, much of the conventional wisdom on vehicle sound package developed from experience with ICE's must be reconsidered. Utilizing an SEA model, the paper discusses the unique problems encountered in designing a noise control package for a fuel cell-based vehicle, the packaging design issues related to space, weight and design restrictions, and presents some initial correlation results. It is concluded that an SEA model can be used to provide design recommendations on the high frequency NVH performance of the vehicle structure. |
Development of a New Standard for Measurement of Impulse Noise Associated With Automotive Inflatable Devices | The SAE Recommended Practice for measuring impulse noise from airbags, SAE J247, ?쏧nstrumentation for Measuring Acoustic Impulses within Vehicles?? was first published in 1971 and last affirmed in 1987. Many advances have occurred in understanding and technology since that time. Work in the automotive industry to investigate the characteristics of noise from airbag deployments has shown that large components of low frequency noise can be present when an airbag deploys in a closed vehicle. Others have shown that this low frequency noise can have a protective effect on the ear. Likewise, work for many years at the US Army Research Lab has investigated the risk of hearing loss for a human subjected to an acoustic impulse. That research led to the creation and validation of a mathematical model of the human ear, called Auditory Hazard Assessment Algorithm - Human (AHAAH). In 1998, the SAE Impulse Noise Task Force (INTF) of the Inflatable Restraint Standards Committee performed a series of experiments to help understand the predictions of the AHAAH model. This work compared in-vehicle test results with those obtained from an acoustic reverberation chamber. These tests used a method published by a German Airbag Consortium called the AK-ZV Working Committee and documented in report AK-ZV01. Much of this work was summarized in SAE J2531, an Information Report developed by the SAE Impulse Noise Task Force, documenting the state-of-knowledge in 2003. Also in 2003, Banglmaier and Rouhana reported on the results of over 100 tests performed to help clarify test conditions for the assessment of noise-induced hearing loss (NIHL). Based on all of this information, a new revision of SAE J247 has been drafted and is in the process of committee editing. This paper describes the changes made to SAE J247 and the rationale for those changes. |
Application of Statistical Noise Generation and Radiation for Aeroacoustic Predictions in the Automotive Industry | Flow-induced noise is an important issue in the automotive industry. TNO in cooperation with AVL developed an efficient hybrid Computational AeroAcoustics (CAA) method, aimed at actual engineering applications, i.e. fast, robust, accurate and able to handle highly complex geometries. The hybrid method is based on standard Reynolds Averaged Navier-Stokes solution of the flow field under consideration, and combines an Statistical Noise Generation and Radiation (SNGR) technique to generate a time-accurate realization of the turbulence and a high order, quadrature-free discontinuous Galerkin - Linearized Euler Equation (LEE) solver to predict the propagation of the acoustic waves. Owing to the unstructured grid strategy the present approach is both particularly well suited for the complex geometries common to car design as well as sufficiently flexible in selecting acoustically interesting subdomains. This paper demonstrates the capabilities of the CAA method in two cases on the noise induced by the flow around a car, and more specifically, by the A-pillar and rear-view mirror on the side window. |
Xtreme Make-Over In 24 Hours | Our conference chairman told me that this special technical section was structured to provide ?쐓ome words of wisdom from the old guys??or something to that effect. I know I can meet most of his requirements. I am a pensioner and an oak tree. However, ?쐗ords of wisdom??maybe a challenge. Solving noise problems, setting acoustical performance targets and guidelines, and developing noise control systems for new and carry-over vehicles can be very challenging and time consuming particularly in today's culture. In the 1970's and 80's, and 90's we had the same challenges. Our customers demanded and appreciated a quiet vehicle. They want to talk to each other without shouting or to enjoy a favorite music selection regardless of weather, road conditions, or vehicle speed. The use of ear plugs or cotton is not acceptable! Noise Gremlins (Figure 1) can ruin a good day! Management, on the other hand, reasonably requires that we accomplish all of these objectives as soon as possible (yesterday preferred), don't spend any money, design it for easy assembly and above all keep-the-lead-out! Don't add any weight to the vehicle! Did your boss make any of these demands recently? |
A Study of NVH Vehicle Testing Variability | At certain key stages in the vehicle development process, prototype vehicles are available for NVH testing. This testing fulfills two functions: primarily it is used to assess the status of the vehicle to the program NVH performance targets, but it also provides an opportunity to validate the vehicle SEA model. These single vehicle test events provide a snapshot of the NVH performance but do not provide any understanding of the variability of the NVH performance, which is due to many factors: components, build or assembly and test setup variability. SEA models can be used to estimate the vehicle level variability, if the variability of the interior components is understood, but there is limited data available to confirm the accuracy of these predictions. In this paper we examine the repeatability and reproducibility through a standard gage R&R study of Engine Noise Reduction (engine NR) and Tire NR testing. We also examine the variation in NR from vehicle-to-vehicle through testing on six compact sedans of the same vehicle line. A more limited chassis dynamometer study on three of the six vehicles is also presented to look at typical running vehicle measures such as articulation index, loudness and overall SPL for tire and powertrain noise. Although the sample population is small, we have extracted estimates of variation in body noise reduction due to test setup, actual component and build variation and the implications for predicting variability through SEA models. |
Electromagnetic Compatibility of Direct Current Motors in an Automobile Environment | As the volume and complexity of electronics increases in automobiles, so does the complexity of the electromagnetic relationship between systems. The reliability and functionality of electronic systems in automobiles can be affected by noise sources such as direct current (DC) motors. A typical automobile has 25 to 100+ DC motors performing different tasks. This paper investigates the noise environment due to DC motors found in automobiles and the requirements that automobile manufacturers impose to suppress RF electromagnetic noise and conducted transients. |
CAE Virtual Test of Air Intake Manifolds Using Coupled Vibration and Pressure Pulsation Loads | A coupled vibration and pressure loading procedure has been developed to perform a CAE virtual test for engine air intake manifolds. The CAE virtual test simulates the same physical test configuration and environments, such as the base acceleration vibration excitation and pressure pulsation loads, as well as temperature conditions, for design validation (DV) test of air intake manifolds. The original vibration and pressure load data, measured with respect to the engine speed rpm, are first converted to their respective vibration and pressure power spectrum density (PSD) profiles in frequency domain, based on the duty cycle specification. The final accelerated vibration excitation and pressure PSD load profiles for design validation are derived based on the key life test (KLT) duration and reliability requirements, using the equivalent fatigue damage technique. The coupled vibration and pressure simulation is then implemented by applying both the base acceleration and pressure pulsation loads to the manifold CAE model, in terms of PSD functions, using the frequency response analysis technique. The computer simulation generates dynamic response of the air intake manifold structure, in terms of stress PSD results at identified hotspot locations. The durability life of the air intake manifold design is then evaluated based on the simulated stress and material fatigue damage model. The fatigue damage model is established from fatigue data of the manifold material obtained at different test temperatures. The presented procedure has helped the engineering team to identify potential durability design problems without a prototype, and to guide the design changes and modifications. It has shown that CAE virtual tests provide a way to speed up air intake manifold product development, and to minimize prototypes and costs. |
Development of the Vibrational EFA (Energy Flow Analysis) Software EFADSC++ R4 and its Applications to Automobiles | The Energy Flow Analysis (EFA) offers very promising results in predicting the noise and vibration responses of system structures in medium-to-high frequency ranges. We have developed the Energy Flow Finite Element Method (EFFEM) based software, EFADS C++ R4, for the vibration analysis. The software can analyze the built-up structures composed of beam, plate, spring-damper, rigid body elements and so on, and has many useful functions. For the effectiveness and convenience of software, the main functions of the whole software are modularized into translator, model-converter, and solver. The translator module makes it possible to use of finite element (FE) model for the vibration analysis at low frequencies. The model-converter module changes FE model into energy flow finite element (EFFE) model. It is generates joint elements to cover the vibrational attenuation in the complex structures composed of various elements and can solve the joint element equations by using the wave transmission approach very quickly. The solver module supports the various direct and iterative solvers for multi-DOF structures. EFADS C++ R4 can also use the analytic parameters input by user. The simulation about the local part of real automobile is performed sucessfully. |
Diagnostics of Engine Noise During Run-up Using HELS Based Nearfield Acoustical Holography | This paper describes the diagnostics of noise sources and characteristics of a full-size gasoline engine during its run-up using Helmholtz Equation Least Squares (HELS) method based nearfield acoustical holography (NAH). The acoustic pressures are measured using an array of 56 microphones conformal to the contours of engine surfaces at very close range. Measurements are collected near the oil pan, front and intake sides. The data thus collected are taken as input to HELS program, and the acoustic pressure mappings on the oil pan, front and intake surfaces are calculated. These reconstructed acoustic quantities clearly demonstrate the ?쐆ot spots??of sound pressures generated by this gasoline engine during its run-up and under a constant speed condition. These acoustic pressure mappings together with order-tracking spectrograms allow for identification of the peak amplitudes of acoustic pressures on a targeted surface as a function of the frequency and engine rpm. This information enables one to correlate a particular drive train order at a specific frequency and rpm to the peak amplitude of the sound pressure at a specific location on the engine surface, e.g., an oil pan. The depth and breadth of clearly defined information obtained can be very helpful to identify noise sources and how they change with the engine speed. |
The Effects of Body Joint Designs on Liftgate Chucking Performance | Liftgate chucking is one of the major squeak and rattle concerns for vehicles with a large body closure opening in the liftgate area. High frequency chucking noise is generated as a result of the contact between the latch and striker of a liftgate. Traditionally, liftgate chucking problems (if present) are found and fixed by using a more robust latch/striker mechanism at a very late design stage that normally results in cost penalties for vehicle programs. Significant effort has been made at Ford in identifying and clarifying up-front drivers or body performance metrics that predominantly influence downstream squeak and rattle sensitivity. Two key body performance metrics (diagonal distortions at the liftgate opening and relative displacement between the latch and striker of a liftgate) are found to affect liftgate chucking sensitivity. The effects of body joint designs on liftgate chucking performance are discussed using these metrics in CAE analyses. A joint design that balances performance, weight and cost is identified in the process. |
On the Relation Between Exposure to Sound and Auditory Performance | This paper presents the results of 10 years of work on the relation between exposure to sound and its effect on hearing. More than ten thousand persons were examined. Highlights of the results are: (a) a person's everyday exposure to sound can have a beneficial effect on hearing such as reducing the effect of aging and lowering the susceptibility to damage; (b) women are more susceptible to low-frequency noise than men; (c) impulsive sound is particularly dangerous to hearing; (d) three different resonances appear to cause most damage after being exposed to intense impulsive sound; and (e) there is a strong relation between the structure of impulsive sound and damage to hearing. With regard to the effect of the peak sound pressure from airbag deployment, driver airbags are less damaging to the ears than firearms because of masking effects. |
An EFEM0-SEA Integrated Model of a Trimmed Van | High frequency responses of structural-acoustic systems may be predicted by statistical energy analysis (SEA) or energy finite element method (EFEM). To combine the good features of these two techniques, a simplified energy finite element method, referred to as EFEM0, has been developed recently. The EFEM0 technique, which is compatible with SEA, integrates the joint coupling procedures for discontinuous systems and the finite volume formulation for continuous system. The EFEM0 models have been verified either analytically or experimentally for one- and multi-dimensional systems. In this study, the EFEM0 technique is applied to a passenger van for a noise control investigation. The general scheme is to incorporate the EFEM0 coupling factors into a SEA model in order to release some SEA assumptions and improve the SEA model, especially for relatively high damping, strong coupling and direct field cases. The EFEM0-SEA integrated model for the trimmed van is validated by experimental data. Several noise control strategies will be discussed for the integrated model to optimize the sound package. |
Sound Package Design for a Convertible by Statistical Energy Analysis | The application of SEA (Statistical Energy Analysis) to the sound package design for a convertible is presented. SEA modeling was used optimize the soft-top construction and the acoustic insulation in the top-stack area (where the soft-top is stored) which were shown to be important transmission paths for tire noise. Correlation between measurement data and predictions from the SEA model is presented and good agreement shown. It is concluded that SEA can be applied to determine the special sound package requirements for convertible vehicles. |
Novel Design of a Multi-Function Acoustics Laboratory for the Testing and Evaluation of Automotive Acoustics Systems and Components | The acoustic performance requirements of vehicle interior trim elements and sound package elements have increased significantly in recent years. Additionally, the burden of developing these products has been shifted from the Original Equipment Manufacturers (OEMs) to suppliers. To aid in developing lightweight, low cost, and high performance parts, a flexible acoustic testing facility was designed for use in many different applications. Specific, purpose-built chambers for only one type of measurement are typically not cost effective facilities. |
Towards a Standard for Material Friction Pair Testing to Reduce Automotive Squeaks | Today vehicle owners perceive squeaks and itches inside a vehicle cabin as a major negative indicator of vehicle build quality and durability. Manufacturers struggle to bear the high costs of squeak and rattle (S&R) related warranty. Although the benefits of structural integrity and tight manufacturing tolerances with respect to the prevention of S&R are known, today's cost, weight, crash requirements, aesthetic demands and environmental/fire hazard rules quite often dictate the design of S&R prone sub-systems. Even sub-systems with the best possible structural design and manufacturing tolerances are not immune to extreme environmental conditions, and mating materials can initiate contact leading to S&R. One method of minimizing the possibility of squeaks is by the judicious selection of mating material pairs. This paper describes a test process aimed at the quantification of material pair compatibility. Also described is a state of the art, flexure-based (virtually frictionless) test instrument that has been developed for such material pair compatibility studies. A group of 17 material pairs with known historical problems were identified by experienced automotive designers and were put through 374 tests encompassing several realistic temperature and humidity extremes in a complex test matrix. Material pair samples were ?쐒ubbed together??in an accurately controlled manner. The types of relative displacement that were used were single excursion pull and realistic road inputs in the form of a shaped random profile. The material pairs included combinations of PVC, ABS, TPO, PP and painted metal from sub-systems such as instrument panels, center consoles, body panels, door trim and weather-strips. Instationary Zwicker loudness was used as a metric for quantifying the squeak in addition to classical friction parameters. From the test data, a classification of the material pairs was made pertaining to their propensity to generate squeak and itch (S&I). Initial levels of correlation with GM material experts' classifications of the same pairs are promising and are the motivation for further studies. The Team (Defiance, GM and MB Dynamics) feels strongly about the need for a comprehensive materials database that is the result of a uniform experimental procedure to identify pertinent material characteristics in order to understand, verify and significantly reduce stick-slip in automotive applications. The Team feels that the test equipment, test procedures and analysis methods that were developed during this project and that are described in this paper, greatly contribute towards this cause. The Team wants to extend the invitation to other interested parties (tribology researchers, scientists, automotive or other engineers), to bundle efforts, share best practices and lessons learned, and work towards a standard for material friction pair testing. |
Design of a World-Class Vehicle Acoustical Laboratory Facility | This paper examines the critical design elements and issues associated with converting facility goals and business objectives into a functional facility. The design of the General Motors Noise and Vibration Analysis Laboratory (NVAL) will be discussed to help clarify key points. A team-oriented design approach is essential to meet the stringent safety, flexibility and operational requirements associated with noise, vibration and harshness (NVH) facilities. The first step is establishing the design team and their respective roles in the process. The challenge of ?쐆ow to build a facility that meets the specified objectives??is addressed in the programming phase. Operational and financial objectives are reviewed and validated. Upon completion of the programming effort, the team attacks the special technical challenges borne out of that process. This is the beginning of the design development phase of the project and involves tackling such issues as acoustic isolation, vibration isolation and HVAC system noise control. The goal is to meet the technical challenges associated with actual facility capabilities and simultaneous testing of different operations within the building. At the conclusion of these critical elements, the design team is prepared to complete the detailed design of the facility and plan for the ensuing construction.(1) This paper offers a summary of the NVH facility design process, as well as key items learned through the course of the GM NVAL design effort. |
Development of Windshield Defogging | South America is traditionally a follow source region where vehicles are mostly developed and validated in the lead development regions with the goal of having a single design applied globally. Most of these developments are proven efficient, which is the case of air conditioning systems, however heating and ventilation systems have particular regional requirements according to details suggested at this paper where we explore regional needs (tropical climate condition) and unique development specifications for windshield defogging. |
Wavelet-Based Visualization of Impulsive and Transient Sounds in Stationary Background Noise | Scalograms based on shift-invariant orthonormal wavelet transforms can be used to analyze impulsive and transient sounds in the presence of more stationary sound backgrounds, such as wind noise or drivetrain noise. The visual threshold of detection for impulsive features on the scalogram (signal energy content vs. time and frequency,) is shown to be similar to the audible threshold of detection of the human auditory system for the corresponding impulsive sounds. Two examples of impulsive sounds in a realistic automotive sound background are presented: automotive interior rattle in a vehicle passenger compartment, and spark knock recorded in an engine compartment. |
Validation and Improvement of Body Panels FE Models from 3D-Shape and Vibration Measurements by Optical Methods | In this paper, we propose a strategy for validation and improvement of structural finite elements (FE) models using vibration and 3D-shape optical measuring method. The main advantage of these methods is to provide a whole field information allowing to speed-up the measurements, combined with an high spatial resolution ensuring updating quality. This strategy is especially adapted to the improvement of light weight body panel structures. Several application examples are presented. |
Evaluation of Wind Noise Sources Using Experimental and Computational Methods | Experiment and CFD have been performed to clarify the distribution of wind noise sources and its generation mechanism for a production vehicle. Three noise source identification techniques were applied to measure the wind noise sources from the outside and inside of vehicle. The relation between these noise sources and the interior noise was investigated by modifying the specification of underbody and front-pillar. In addition, CFD was preformed to predict the noise sources and clarify its generation mechanism. The noise sources obtained by simulation show good agreement with experiment in the region of side window and underbody. |
Electromagnetic Compliance Issues of Project Oculus | Project Oculus, an experimental configurable sensor platform for deploying airborne sensors on a C-130 aircraft, is currently in its pre-flight testing phase. The electronics driving the platform are available commercially off the shelf (COTS) and as such are not automatically rated to comply with stringent military electromagnetic standards as defined in MIL-STD-461. These COTS electronics include efficient switching power converters, variable frequency motor drives (VFD), and microprocessor based equipment, all of which can present electromagnetic interference (EMI) issues. Even in a design where EMI issues were not considered up front, it is often possible to bring the overall configuration into compliance. Switching and digital clock signals produce both conducted and radiated noise emissions. Long cable runs and enclosure apertures become noise transmitting antennas. Large switching currents place noise on the power lines causing interference with other equipment. These problems became apparent during initial EMI compliance testing. This publication will outline the shielding and filtering techniques used to resolve these problems in preparation for flight testing and evaluation. |
University of Idaho's Clean Snowmobile Design Using a Direct-Injection Two-Stroke | The University of Idaho's entry into the 2005 SAE Clean Snowmobile Challenge (CSC) was a second-generation gasoline direct-injection (GDI) two-stroke powered snowmobile. A battery-less direct-injection system was used to decrease exhaust emissions and improve fuel economy without reducing the power output of the engine. A spiral exhaust silencer was used to reduce exhaust noise. Under-hood noise was targeted by using sound absorbing materials and a sealed hood. Chassis noise was addressed by using a spray-on rubberized material that absorbs vibrations transferred through the chassis. Power transfer and space issues were addressed with the addition of a direct-drive system that eliminated the jackshaft. The snowmobile entered into the 2005 SAE CSC competition was lightweight, fun-to-ride, powerful, and had reduced exhaust emissions. |
Active Noise Control Simulation in a Passenger Car Cabin Using Finite Element Modeling | According to the importance of Active Noise Control (ANC) in 3D spaces such as vehicle cabins for reducing unwanted noises inside cabins, the purpose of this paper is to demonstrate the finite element (FE) modeling, simulation and analysis of an ANC in a 3D acoustic passenger car cabin with filtered-X LMS adaptive feed forward controller. For this purpose, after creating an acoustic FE model of the passenger car cabin and calculating its resonance frequencies and mode shapes; several transfer functions of primary, secondary and feedback paths of the acoustic field is estimated in digital domain in accordance with frequency responses obtained from FE model in order to simulate the behavior of ANC system. In all simulations, acoustic feedback effect is considered and the acoustic feedback neutralization technique is used to reduce or overcome the instability potential of this effect. The performance of different configurations of multi-channel ?쏤XLMS??ANC systems is studied with ?쐎ff-line??modeling technique using Finite Impulse Response (FIR) filters. The obtained results are useful for optimal placement of secondary sources and error microphones. It is found that, the acoustic pressure attenuation inside cabin can be significantly reduced if the control source is placed in close proximity to the reference microphone. However, increasing the number of sensors and/or the number of control sources located remotely from the primary source, have little impact on the maximum achievable reduction in the acoustic pressure in the cavity. |
Productive measurement of transmission loss characteristics using Nearfield Acoustic Holography | A continuously growing demand comes from the automotive industry for optimisation of materials and sound insulating products implementation inside the car, in order to propose the best acoustic performance at reduced costs. As already presented last year at SEA Brazil [9], the approach based on extensive use of the acoustical holography system dBVISION of 01dB-METRAVIB provides part of the solution to such a demand. Whereas the first paper was dedicated to some general considerations and practical aspects of NAH implementation inside a car, the one proposed for the 2005 session is focused on a very important aspect of NAH measurements, namely productivity, for both inside and outside measurements. The paper reviews the NAH technique advantages for measuring the acoustic field inside and outside a vehicle and performing extensive studies on transmission loss characteristics of panels and car openings, with the aim of: detailed localization of possible acoustic weakness points on single components, ranking of the tested components in terms of global and partial radiated power contribution driving possible optimisation of component in the early stages of the design cycle The applied test set-up will be presented and its main features regarding productivity improvement will be highlighted, with a special attention to the compact and versatile robotized instrumentation used for this type of measurements. The presentation will be illustrated by operational results in different situations and some possible extension will be proposed in order to open this technique to the efficient characterization of 3D-shaped structures. |
Reference vs. Preference: The ?쏶urround??of Surround Sound | Surround sound provided by stereo and 5.1 systems may not be satisfying all its listeners. Whether in the automobile or in the home, customers complain of ?쐍othing from the rear speakers?? or about the sound ?쐍ot filing the room?? etc. While 5.1 systems promise more surround, the economics of music production and concerns of music professionals are likely causing stereo to dominate production resources and causing 5.1 mixes to miss their full potential. The author believes that post-processing electronic and acoustic manipulation can produce sound that customers will prefer. A controlled experiment was performed which compared reference stereo and surround systems to ones augmented by extra surround equipment. This paper: 1 Discusses a very brief history of stereo and surround sound 2 Describes an experiment used to test listener preference, 3 Details experimental results when comparing reference-like music presentation with envelopment enhancing sound processing using both stereo and 5.1 recorded music. |
Application of Novel Viscoelastic Microcellular Foams for Passive Noise Control in Automotive Body Structures | This paper discusses the development of lighter weight, superior acoustic performance and cost effective viscoelastic microcellular foams for the use in automotive passive noise control panels. The study incorporates the control of the foaming process for production of variable microcellular structures and morphologies for the novel foams under investigation. For that purpose, the foaming process was controlled for production of foam samples with various microcellular structures. Cross linked LDPE was used as a base material for the produced foams. Very high open-cell content (ranging between 43 - 95%), high microcellular cell densities (9E108 - 1.6E109 cells/cm3) and desired expansion ratios (3 - 9 folds) were successfully obtained. While the material is overly porous, it is noted that the unfoamed skins on the outer surfaces of the samples have prevented sound waves from penetrating the samples. Manual skin removal resulted in slight improvement in sound absorption testing. However, in order to get more reliable data, skinless samples need to be produced. |
Creation of a Brake Development City Traffic Vehicle Test in Shanghai / Suzhou, China | As automotive manufacturing increases in China, boosting the sales of OEM and aftermarket brake system components, it becomes increasingly important to address customer and manufacturer concerns regarding the implementation of localized testing. In response to the growing demand to understand noise and component wear characteristics, research to assess representative city traffic patterns in the city and suburbs of Shanghai/Suzhou, China has been conducted. With this data, a procedure for operating a city traffic vehicle test in China has been developed and documented in this paper. This testing process provides data that quantifies lining and rotor wear, brake energy levels, lining temperatures, component NVH, and other brake system qualities. Through the standardization of this procedure, OEM suppliers, aftermarket vendors, and other interested parties will have the means necessary to execute controlled and standardized vehicle level brake testing which generates data for the purposes of predicting brake wear and noise performance. |
Noise Suppression chips in Small Motors | Expanding the applied frequency bandwidth to include higher frequencies of conducted and radiated electromagnetic interference (EMI), has brought all inductive devices including the small sub-fractional motor to the attention of vehicle manufacturers5. The surface mounted noise cancellation chip can be combined with design strategies to reduce, contain, and attenuate the natural occurring broadband EMI phenomenon in the permanent magnet direct current motor. |
Optimization Study for Sunroof Buffeting Reduction | This paper presents the results of optimization study for sunroof buffeting reduction using CFD technology. For an early prototype vehicle as a baseline model in this study a high level of sunroof buffeting 133dB has been found. The CFD simulation shows that the buffeting noise can be reduced by installing a wind deflector at its optimal angle 40 degrees from the upward vertical line. Further optimization study demonstrates that the buffeting peak SPL can be reduced to 97dB if the sunroof glass moves to its optimal position, 50% of the total length of the sunroof from the front edge. For any other vehicles, the optimization procedure is the same to get the optimal parameters. On the other hand, however, this optimization study is only based on fluid dynamics principle without considering manufacturability, styling, cost, etc. Further work is needed to utilize the results in the production design. |
Subsets and Splits