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Flexible ?쏶kin??Senses Shear Force | To date, it has been difficult or impossible for most robotic and prosthetic hands to accurately sense the vibrations and shear forces that occur, for example, when a finger is sliding along a tabletop, or when an object begins to fall. Some robots today use fully instrumented fingers, but that sense of touch is limited to that appendage, and its shape or size cannot be changed to accommodate different tasks. The other approach is to wrap a robot appendage in a sensor skin, which provides better design flexibility; however, such skins have not yet provided a full range of tactile information. |
Disc Brake Squeal | Chapters written by professional and academic experts in the field cover: analytical modeling and analysis, CEA modeling and numerical methods, techniques for dynamometer and road test evaluation, critical parameters that contribute to brake squeal, robust design processes to reduce/prevent brake squeal via up-front design, and more. |
Up-Front Body Structural Designs for Squeak and Rattle Prevention | 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. A research work at Ford reveals a correlation between the squeak and rattle performance and diagonal distortions at body closure openings and fastener accelerations in an instrument panel. These findings make 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 is concerned with applications of this squeak and rattle assessment method for up-front body designs prior to a prototype stage. |
Aerospace Engineering 2005-08-01 | Global technologies Much of the excitement surrounding such aircraft as the point-to-point 787, hub-to-hub A380, and 7X business jet is due to the application of new technologies. Engineering a career With an impending shortage of aerospace engineers, industry and academia team to mold future engineering talent for an increasingly global environment. Taking research to the bank Behind the doors of BAE Systems' Advanced Technology Center. Testing toward perfection In a competitive global market, commercial aircraft need to be lighter, faster to market, cheaper to build, easier to maintain, and safer than ever. |
Automotive Engineering International 2003-04-01 | Phantom materializes BMW's Rolls-Royce Motor Cars unveils its first model, an aluminum-bodied sedan with rear-hinged rear doors and a new V12. Protecting the cabin from powertrain NVH OEMs are getting help from suppliers such as Collins & Aikman and Bayer in damping NVH, thanks to innovation in plastics. Forced induction Environmental pressures prompt renewed interest in turbochargers and superchargers. Collaboration software emerges Interactive product development tools that can decrease design time and cost, enhance quality, and improve engineering processes are now widely available. Validated virtual testing DaimlerChrysler and MTS Systems have verified that component load histories can be predicted before prototypes are built. Automation: a tool, not an end Toyota and its suppliers try to strike a balance between automation and manual labor at their U.S. plants. Rouge: symbol of past points to future A rebirth at Ford's famous manufacturing complex honors the past but puts the focus on the future. Aluminum and the XJ Its construction and the techniques used to build it dominate the sixth-generation Jaguar sedan's technology story. Driving the Hy-wire GM's Larry Burns sees the alliance of fuel-cell and by-wire technologies as an essential element in the development of tomorrow's vehicles. |
Automotive Engineering International 2005-11-01 | Frankfurt (Hybrid) Motor Show Dual-power technology was driven through the doors of the huge German complex in a way that has never been seen before. Bringing good things to light Emerging lighting technologies deliver more design flexibility as they get brighter, smarter, and smaller. Tightening supply chain links Improved electronic tools and more outsourcing fuel increased collaboration. Extreme two-wheeler engineering American Motorcyclist Association Superbike racing spurs development of truly super street bikes. Engineering for the aftermarket Suppliers that serve the OE market are setting their sights on the growing market for customization. |
Two Projects and Free Advice | A review of two particular projects from the '60s, will be presented. One pertains to doing a modal, before they were called that, using accelerometers and an oscilloscope for manual readout and graphing. The other relates to making best use of an early hardware design for best available noise control. The free advice will relate to presentations of data purporting to represent how people may judge in-vehicle sound and how we might learn about human response from the another industry. |
An Advanced Optic Rear Vision Device for Motor Vehicles | The outside rear view mirrors on motor vehicles are located outside a vehicle's solid body, normally attached to the side doors. Owing to their contour and positions, they present certain drawbacks which may cause dangers on the road, especially under unfavorable conditions when both the side door glasses and the surface of the outside mirrors are contaminated. An advanced optic rear view mirror unit has been designed and developed, with the aim to eliminate all the drawbacks of said outside rear view mirrors and hence to enhance the traffic safety. It shows that the said mirror unit eliminates the aerodynamic drags and sight blocks caused by the protrusion of conventional outside mirror bodies, places the rear vision inside a vehicle at a more logical physical position related to the driver, and provides an always clear view to the rear area regardless the outside weather conditions. |
A New State-of-the-Art Keyless Entry System | A new keyless entry system, for automotive security and comfort applications, has been developed. The system utilises a single chip transponder for vehicle immobilisation, keyless entry and remote control functionality. The transponder system can be embedded into a key fob or an ISO smart card. System security and communication speed is provided by an advanced anti-collision protocol in combination with sophisticated challenge response and uni-directional protocols. The system can be activated by using either a push-button transponder, where long range access to the vehicle is provided, or by touching an actuator near the door or trunk. Due to the inductive coupling between the transponder and the vehicle mounted antennas, the vehicle door or trunk opens on successful verification as if there were no locks. Additionally, inside the vehicle, the transponder can be used as an immobiliser. |
Recycling of Mixed Color Automotive Thermoplastics | A method for recycling of mixed color automotive thermoplastic scrap into appearance automotive interior parts has been developed and shown to satisfy the following three requirements: 1) material performance 2) color appearance, and 3) economically sound. The technique developed is based on minimal separation of the colors into hues (groups of similar colors) and repigmenting to the desired color. The studies included computer formulations, laboratory verifications and plant runs. Plant runs were carried out to produce automotive interior doors (base level S-truck) with polypropylene (PP) regrind and B-pillar 325 parts with acrylonitrile-butadiene-styrene (ABS) regrind at the Delphi - Adrian plant. Two colors, ruby red and medium gray, were selected because they are the most difficult colors to match. The results of the plant runs demonstrated that color matching can be successfully achieved. The total color difference in CIELAB color space (DE) of the recycled automotive parts to GM color standards was less than 0.87 with compositions of 20% and 30% of a one hue dominant PP and ABS regrind fraction at less than 2% pigment loading. The recycled automotive parts also met other requirements for mechanical and physical properties specified by the GM standards including GM's UV resistance requirements. |
Total Interior Systems Integration | The current and future greatness challenge for the car and light truck manufacturer is to develop less costly, weight efficient vehicles within shorter lead times. Based upon these circumstances, the technique of ?쐓ystems design?? ?쐓ystems integration??and ?쐔otal interior systems integration??will be discussed in detail. Component integration and systems integration has been taking place in automotive interior design for sometime. However, total systems integration is relatively new. A potential area for interior systems integration application is in side impact ?쐕pgrade?? For added side impact protection the door structure and impact beam can be upgraded, a side air bag utilized, door/sill interlock, crushable arm rest, etc. Individually, each of these systems could meet the new side impact requirements; however, at a cost, weight and quality penalty. Utilizing two or more of these systems in combination could lead to an optimum solution (total systems integration). Other systems related to the body interior that can be designed by total systems integration are seats and I/P's. In addition to the interior system integration examples presented, a discussion will be presented regarding a new CAD design and CAM processing method called ?쐌orphing??which can enhance the optimization of systems integration. |
Evaluation of Tailor Welded Blanks Through Technical Cost Modeling | In the past decade, the demand for and development of tailor-welded blanks (TWBs) has increased dramatically. TWBs help reduce body mass, piece count and assembly costs, while potentially reducing overall cost. IBIS Associates, Inc. has performed a cost analysis of tailor welded blank manufacturing through the use of Technical Cost Modeling (TCM), a methodology used to simulate fabrication and assembly processes. IBIS has chosen the automobile door inner panel for comparison of TWBs and conventionally stamped door inners with added reinforcements. Manufacturing costs are broken down by operation for variable costs (material, direct labor, utility), and fixed costs (equipment, tooling, building, overhead labor, maintenance, and cost of capital). Analyses yield information valuable to process selection by comparing cost as a function of manufacturing method, process yield, production volume, and process rate. |
Application of Fibre-Reinforced Composites in the Car Side Structure | In this paper the general requirements for a passenger-car side door made of FRP are presented as well as a description of different concepts for self supporting monocoque FRP-doors. For one conceptual design static and dynamic analyses have been made to investigate more detailed the potential of composites in this application. The results of the structural analyses, which have been investigated by commercial FEA-codes, are presented. The research data resulting from completed testing of components are compared with the simulation results. On the basis of this research a prospect for the application of FRP in the field of side impact protection is given. |
PVB Interlayer Performance Requirements for Laminated Side Glazing | Laminated side glazing is a rapidly growing new application, driven by consumer demand for improved intrusion resistance and increased comfort. Performance requirements for movable door glass applications are different from laminated windshield (LWS) needs. Criteria for satisfactory performance are discussed and the performance of commercially available interlayers compared. Performance differences are significant, indicating that interlayer selection is critical for acceptable side glazing performance. The most important performance attribute is the ability to maintain adhesive bond strength to glass at the high interlayer moisture content present at exposed edges. |
An Objective Measure of Severity for Small Topographical Defects in Automotive Paint | In this evaluation eight observers viewed small topographical defects in paint samples out of doors and in a mock inspection facility. Each observer rated defect severity and the probability of returning a new vehicle with these defects to the dealer for repair. Severity ratings for defects viewed under the recommended inspection lighting were the same as those made outdoors. A nonlinear model relating the probability of a repair request to defect severity (R2 = .95) is provided. A method of measuring the essential physical attributes of the defect, specular highlight area and modulation, is described. A second model relating defect severity to the essential defect attributes (R2 = .88) is provided. |
Static Electricity in Automotive Interiors | Seats and carpets were evaluated for generating static charges on vehicle occupants. Active measures that eliminate or reduce static accumulation, and passive measures that dissipate static charge in a controlled manner were investigated. The active measures include using durable anti-static finishes or conductive filaments in seating fabrics. The passive measures include adopting conductive plastics in a steering wheel, seat belt buckle release button, or door opening handle. The effectiveness of these measures was tested in a low humidity environment. |
Input Loading for Squeak & Rattle CAE Analysis | A method to create a CAE load by utilizing the vibration motions at structure attachments has been developed. This method employs the concept of enforced motion as the constraints of boundary conditions to create an equivalent input force/moment matrix for a sub-structure with multi-point attachments. The main assumption is that motions at the attachments of the sub-structure should be the same as the known motions of the main structure under the generated input load. The key concept of the developed methodology is the calculation of the input dynamic compliance matrix for sub-structure attachment locations. This method is developed to create a system level input load to be used for squeak and rattle CAE analysis on a component or sub-system. It can also be used for minor component design change evaluation using only the component CAE model, yet as if it is assembled in the vehicle. It also enables the creation of CAE system level loads for non-structural trimmed body components such as the door trim panel and the floor console which are not included in a typical trimmed body CAE model. Two example cases are provided to show the usage and accuracy of the methods. The first example is a simple rectangular plate to serve as a benchmarking problem. The second one is an instrument panel on a typical sedan. |
USING CROSS-LINKED OLEFIN FOAM IN AUTOMOTIVE INTERIOR PADDED TRIM COMPONENTS | Considerable changes are occurring in automotive interior components in terms of design, aesthetics, and performance expectations. Consequently, new combinations of materials and production methods are being evaluated to meet these changing demands and requirements. One promising example of this is the use of a lightly cross-linked, olefin-blend foam sheetstock for many of the most visible interior padded trim components: door panels, instrument panels, consoles, glove-box/airbag doors, and seatbacks. Olefin foam sheet has a versatile processing profile using any of several interior-trim molding processes, including low-pressure molding, vacuum forming, compression molding, and structural reaction injection molding. In addition, the olefin foam offers excellent formability, with potential overall reduction of processing steps and systems costs. This paper describes the features and benefits of these new padded trim materials in different molding processes vs. competitive expanded polyvinyl chloride foams, including results of recent testing. Data on various skin/foam laminates are presented in terms of key properties required for each of the major processing methods for door trim panels and instrument panels. |
A BE Model for the Analysis of the Effects of Seats in the Passenger Compartment Acoustic Behaviour | The aim of this work is to validate a BE numerical methodology to calculate how the acoustic properties of seats can affect the acoustic behaviour of the passenger compartment of a vehicle. An analytical model, based on the Delany and Bazley approach, was implemented in order to simulate the acoustic impedance of the foam-fabric system. This model has been validated with absorption coefficient measurements on a certain number of foam-fabric combinations. The calculated impedance was used as input for a BEM analysis of the interior cavity of a trimmed vehicle. The measured impedance of trimming components as floor carpet, door panels and parcel shelf were included into the cavity model. The acoustic field due to a known source with and without seats was calculated, in the frequency range 20-400 Hz: the calculated FRFs are in good agreement with the measured ones. The analysis has demonstrated that the presence of seats does not improve the absorption of the passenger compartment in the frequency range investigated: the seats modify the peak position in the FRFs but do not lower their level. Reverberation time measurements made in the passenger cavity with and without seats have, on the contrary, put into evidence an important seat contribution in lowering the interior noise above 1000 Hz: the reverberation time in this frequency region has been reduced by about 50% by the presence of seats. |
Use of FEA Concept Models to Develop Light-Truck Cab Architectures with Reduced Weight and Enhanced NVH Characteristics | Many recent developments in automotive technology have resulted from the need to improve fuel economy without sacrificing passenger comfort or safety. This paper documents an effort to reduce the weight of dual-use military/civilian vehicles through the use of innovative design architectures. Specifically, a number of crossmember architecture concepts were developed for the cab floorpan of a light-duty truck. The floorpan is a key structural component of any vehicle, providing a significant contribution to noise, vibration, and harshness parameters such as stiffness and normal modes. Finite element concept models of the baseline cab and concept cabs are used to show that changes in the crossmember architecture can significantly reduce cab weight without compromising structural performance. |
Continuously Produced Honeycomb Sandwich Materials for Automotive Applications | The demands for automotive interior and exterior panels request an optimal combination of materials and cost efficient production processes. Mechanical and acoustical requirements and a weight target result today often in the selection of a sandwich design with a cost efficient and recyclable core material. Two new cost efficient honeycomb materials and their continuous production processes have been developed at the K.U.Leuven. These materials and production methods enable an automated in-line production of paper and polypropylene (PP) based honeycombs for automotive sandwich panels and parts. The production concepts, possible material combinations and basic material properties for automotive sandwich parts are presented. |
Proposal on New Design of Laminated Glass for Weight and Cost Reduction | This paper presents the proposal on the new design of laminated glass to solve the problems which conventional laminated glass will face when the adoption of laminated glass to side and rear windows extends even to mid-priced models from the safety and security requirements. The thermoset transparent adhesive foils tradenamed ?쏣VASAFE??and the hard coated PET films which are the important elements enabling the proposed laminated glass are first introduced in details and then, the various test results on the proposed laminated glass are indicated and its advantages are made clear. |
Panel Noise Contribution Analysis: An Experimental Method for Determining the Noise Contributions of Panels to an Interior Noise | A new method for estimating the sound pressure level (SPL) at a defined position of the interior is presented. It is possible to recalculate the interior noise dependent on the sound radiated by specified panels which encloses the interior. It could be applied to analyse the interior acoustics under different operating conditions. This could be normal driving on real roads or pure wind noise inside wind tunnels. Also it is possible to study the interior noise under an artificial force excitation applied to the trimmed body. The method is based on the theoretical background of TPA (= Transfer Path Analysis /1/ ) via matrix inversion. It was tested on a simple cuboid structure with an artificial force excitation. The comparison of the measured and recalculated SPL of the interior shows a good correlation. Also the influence of some physical modifications at identified critical areas corresponds with the expected influence to the measured SPL inside this structure. After this first test, for a wind noise excitation a real car structure was investigated. Again the comparison of the measured and recalculated SPL inside the car shows a good correlation for a wide frequency range. At last the method is discussed dependent on possible applications and alternatives which can be used for determining the noise contribution of the panels. Also a perspective in next steps of development and further applications is given. |
Automotive Noise and Vibration Control Practices in the New Millennium | The approaches used to develop an NVH package for a vehicle have changed dramatically over the last several years. New noise and vibration control strategies have been introduced, new materials have been developed, advanced testing techniques have been implemented, and sophisticated computer modeling has been applied. These approaches help design NVH solutions that are optimized for cost, performance, and weight. This paper explains the NVH practices available for use in designing vehicles for the new millennium. |
Full- and Model-Scale Scrutiny of the Effects of Vehicle Windshield Defrosting and Demisting on Passenger Comfort and Safety | Maintaining adequate visibility at all times, through a vehicle windshield, is critical to the safe usage of the vehicle. The ability of the windshield defrosting and demisting system to quickly and completely melt ice on the outer windshield surface and remove mist formed on the inner surface is therefore of paramount importance. The objectives of this paper are to investigate the fluid flow and heat transfer on the windshield as well the effect of the air discharge from the defroster vents on passenger comfort. The results presented are from numerical simulations validated by experimental measurements both carried out a model and full-scale. The numerical predictions compare well with the experimental measurements at both scales. The effects of the defrosting and demisting air on occupants' comfort and safety are examined. |
Automatic Demisting Control of Automobile Windshield Glass | This paper describes the development of the control device for automatic demisting. The control is started from the mist possibility(MP) = 0, which is defined as the temperature difference between dew point and glass surface temperature. The control strategy for automatic demisting was installed in FATC unit and successfully demonstrated by the vehicle test in cold and hot chamber, ranging from 0째 to 30째C. |
Parametric Study on Automotive Windshield Defrost Pattern using CFD | Prediction of automotive windshield defrost pattern using CFD is becoming increasingly important as a complement to cold chamber and field testing to achieve the improved windshield defrosting performance while reducing vehicle development time and cost. Although CFD simulation is popular and convenient, the efficiency and accuracy of simulation somewhat strongly depend on the simulation parameters such as choice of computational grid system, boundary conditions handling, flow consideration including turbulence model, and so on. In this investigation, parametric study on automotive windshield defrost pattern using CFD was performed about simplified passenger compartment. The objectives of this study are to examine the effects of each para-meter and derive the optimized simulation methodology of windshield defrost pattern. |
Reducing Vehicle Auxiliary Loads Using Advanced Thermal Insulation and Window Technologies | Advanced lightweight insulation and window technologies can contribute significantly to achieving industry and government goals of substantially improving fuel economy without loss of vehicle performance or passenger comfort. Two conventional passenger automobiles, a 2001 sport-utility vehicle (SUV) and a 1999 mid-size sedan, were retrofitted with lightweight insulation; the sedan was also fitted with specially designed windows. The body insulation and windows reduce heating and cooling loads, which allows downsizing of heating, ventilation, and air conditioning (HVAC) equipment. Benefits derived from the use of advanced insulation and window technologies include: Demonstrated reductions in cooling loads; Fuel savings for conventional and hybrid vehicles; Extended range for electric vehicles; Greatly improved passenger comfort; Reduced degradation of interior surfaces; and Improved safety. The research vehicles were retrofitted with Lawrence Berkeley National Laboratory's (LBNL) patented gas-filled panel (GFP) insulation. GFPs are multi-layer baffle constructions made from lightweight films and filled with a low-conductivity gas. These lightweight panels can be up to three times as effective as conventional foam insulations depending on the type of gas used. The GFPs used in the automobile retrofits had a krypton or xenon gas fill, which provides an effective thermal resistance of R-12 per inch and R-20 per inch, respectively. By comparison, expanded polystyrene has a thermal resistance of R-5 per inch. The solar-control glazings used in the sedan retrofit consist of special coatings, which create a narrow-band-pass filter that rejects ultra-violet and infrared (IR) wavelengths. The result is much less heat gain into the interior of the car and less degradation of interior surfaces. The retrofitted cars were tested under driving conditions in a wind tunnel and in an outdoor setting. Test results show that vehicle warm up under soak conditions (vehicle parked in the sun) was delayed compared to a factory vehicle. |
Guidelines for Using Fast Multipole BEM to Calculate Automotive Exterior Acoustic Loads in SEA Models | Automotive interior noise at mid and high frequencies is typically dominated by the airborne noise from acoustic sources that are spatially distributed around a vehicle. Each source is typically spatially compact (for example, a tire contact patch) but the source radiates sound that then propagates across the entire exterior surface of the vehicle. To characterize a source it is therefore necessary to know both the sound pressure level in the vicinity of the source and also the way in which sound from the source diffracts around the vehicle. The former depends on the details of the source, the latter typically depends on the overall vehicle geometry. When creating Statistical Energy Analysis (SEA) models of interior noise, the diffraction of airborne loads around a vehicle is often measured experimentally. Since SEA deals with averaged quantities, it is typically only necessary to obtain an approximate estimate of the space and frequency averaged sound pressure level across various surface regions of the vehicle (rather than a very detailed narrowband prediction of the diffraction). This paper provides a numerical investigation of the diffraction of typical acoustic sources around a vehicle using the Fast Multipole Boundary Element Method (FMM BEM). In particular, the paper investigates the sensitivity of the space and frequency averaged diffracted field to various modeling details (for example, geometric detail, mesh density/quality, surface impedance, frequency resolution etc.). The objective of the study is to investigate how much ?쐂etail??is needed in an FMM BEM model in order to get accurate predictions of the exterior acoustic loads for use in Statistical Energy Analysis (SEA) models. Significant reductions in computational expense can be obtained by matching the level of detail in the FMM BEM model to the level of detail required in the input results for an SEA model (and therefore avoiding ?쐎ver computing??results that are subsequently frequency and space averaged). |
Development of a New Squeak and Rattle Detection Algorithm | A new algorithm to detect and to quantify the seriousness of the detected squeak and rattle (S&R) events was developed. A T-F analysis technique called AWT, the Zwicker loudness model and leaky integration are employed to define new concepts we called transient specific loudness time histories and perceived transient loudness time history. The detection threshold of the perceived transient loudness was identified by a clever interpretation of jury test results. The proposed algorithm showed a good promise producing results that are well correlated with the jury tests. The new algorithm developed in this work will be able to automate detection and rating of the S&R events with good accuracy and with minimum possibility of false alarm under normal operating conditions |
Theoretical/Experimental Study on the Vibrations of a Car Engine | The influence of the inertia properties (mass, centre of gravity location, and inertia tensor) on the dynamic behaviour of the engine-gearbox system of a car is studied in this paper, devoting particular attention to drivability and comfort. The vibration amplitudes and the natural frequencies of the engine-gearbox system have been considered. Additionally, the loads transmitted to the car body have been taken into account. Both the experimental and the theoretical simulations confirmed that the engine-gearbox vibrations in the range 10 - 15 Hz are particularly sensitive to slight variation of the inertia properties. The effects on engine-gearbox vibrations due to half-axles, exhaust system, pipes and inner engine-gearbox fluids have been highlighted. |
Vehicle NVH Analysis Using EFEA & EBEA Methods | The Energy Finite Element Analysis (EFEA) has been developed for computing the structural vibration and the interior noise level of complex structural-acoustic systems by solving governing differential equations with energy densities as primary variables. Results from EFEA simulations have been compared successfully with test results for Naval, automotive, and aircraft structures. The Energy Boundary Element Analysis (EBEA) has been developed for exterior acoustic computations using the acoustic energy density as primary variable in the formulation. EBEA results have been compared successfully to the test results in the past for predicting the exterior acoustic field around a vehicle structure due to external noise sources. In this paper, the EBEA and EFEA methods are combined for predicting the interior noise levels in a vehicle due to exterior acoustic sources. The EBEA is employed for computing the acoustic field around a vehicle structure due to exterior acoustic noise sources (i.e. tire source, engine source, etc.). The computed exterior acoustic field comprises the excitation for the EFEA analysis. The vehicle structure, the acoustic treatment, and the interior acoustic volumes are represented in the EFEA model. The interior noise level in the vehicle is computed by the EFEA. Predictions of interior noise level (expressed in a noise reduction format) are compared favorably with test results for two separate types of excitation. |
High Frequency Vibro-Acoustic Analysis Using Energy Finite Element Method | As an alternative method to Statistical Energy Analysis (SEA), Energy Finite Element Method (EFEM) offers several unique advantages for vibro-acoustic analysis of structural-acoustic systems. In this paper, the theory of the energy finite element method is overviewed. The main developments of a recently available EFEM code are presented. This is followed by the investigation of several example problems using EFEM; (a) the acoustic pressure computation in an acoustical duct, (b) the sound transmission loss of an automotive dash, and (c) the vibro-acoustic analysis of a truck cab. The EFEM predictions are compared to the analytical solutions, SEA predictions or test data and good correlations are observed. Further, the advantages of EFEM in the solution of high and middle frequency vibro-acoustic problems are discussed. |
Probabilistic Reanalysis Using Monte Carlo Simulation | An approach for Probabilistic Reanalysis (PRA) of a system is presented. PRA calculates very efficiently the system reliability or the average value of an attribute of a design for many probability distributions of the input variables, by performing a single Monte Carlo simulation. In addition, PRA calculates the sensitivity derivatives of the reliability to the parameters of the probability distributions. The approach is useful for analysis problems where reliability bounds need to be calculated because the probability distribution of the input variables is uncertain or for design problems where the design variables are random. The accuracy and efficiency of PRA is demonstrated on vibration analysis of a car and on system reliability-based optimization (RBDO) of an internal combustion engine. |
Glass Debris in Rollover Accidents | Vehicles involved in rollover accidents almost always leave a debris trail. This debris trail is useful for the accident reconstructionist; it assists with identifying the vehicle path during the rollover and the location and orientation of the vehicle at various vehicle to ground contacts. Often it is helpful to know when and where various vehicle windows fractured. This is possible by comparing glass obtained from the accident site with glass samples still attached to the accident vehicle. The limit of this analysis is controlled by the manufacturing tolerance of the vehicle glass and the specified pane thickness. This paper presents a series of measurements made on various automotive tempered windows and presents: 1) the thickness range in individual panes, and 2) the thickness variation seen from pane to pane in the same vehicle. |
CAL STATE FULLERTON FINDS WINNING FORMULA IN COMBINING ART AND ENGINEERING | Team wins Generation Auto video contest in a year marked by great improvement in its Formula SAE performance. THE CHALLENGE: Create and submit a 1-2 minute video highlighting the diverse aspects of the automotive industry that make it an attractive or ?쐁ool??industry to work in. The qualification: Participate in an SAE International Collegiate Design Series event. |
Modeling process and validation of Hybrid FE-SEA method to structure-borne noise paths in a trimmed automotive vehicle | The Finite Element Method (FEM) and the Statistical Energy Analysis (SEA) are standard methods in the automotive industry for the prediction of vibrational and acoustical response of vehicles. However, both methods are not capable of handling the so called ?쐌id frequency problem?? where both short and long wavelength components are present in the same system. A Hybrid method has been recently proposed that rigorously couples SEA and FEM. In this work, the Hybrid FE-SEA method is used to predict interior noise levels in a trimmed full vehicle due to broadband structure-borne excitation from 200Hz to 1000Hz. The process includes the partitioning of the full vehicle into stiff components described with FE and modally dense components described with SEA. It is also demonstrated how detailed local FE models can be used to improve SEA descriptions of car panels and couplings. After review of the Hybrid FE-SEA models of a full vehicle that were built, sample experimental validation results of interior SPL and panel vibration are shown. |
Acoustic and Structural Treatment of Body-in-White | Automotive body structures are developed to meet vehicle performance requirements primarily based on ride and handling, crashworthiness, and noise level targets. The body is made of a multitude of sheet metal stampings welded together. Other closures such as fenders, hood, doors and trunk lid are developed to match body interfaces, to contribute and participate in the overall vehicle response, and to meet the sub-system and system structural requirements. In order to improve performance and achieve weight reduction of the overall vehicle steel structure, new polymeric materials and treatment strategies are available to body structural engineers to optimize the response of the vehicle and to tune vehicle performance to meet specified functional requirements. If early integrated to the design cycle, these materials help not only improve the structural body response, but also decrease the weight of the integrated body structure. |
Family of High Modulus (HMG) Nylon Based Plastics Increases Mileage and Reduce Weight | Resent developments were oriented on two high-flow, high-modulus grades fiber-glass reinforced nylon 6 (HMG series) grades for transportation, autos and other industrial applications requiring high stiffness, high strength and high fatigue resistance. These materials combined the following improved technological (injection molding, vibration and hot plate welding, etc.) and mechanical performance properties such as greater dimensional stability, higher short-term (strength and stiffness) and long-term (fatigue and creep with the influence of temperature effects). Both HMG series grades Capron짰1 HMG10 and Capron짰 HMG13 - are for injection molded parts where stiffness, strength, impact resistance, and good surface and improved appearance are preferred. The current and possible applications of these plastics includes auto mirror housing brackets, clutch pedals, clutch master cylinders, ski bindings, steering wheels, levers, auto seat frames, door handles and door lock mechanisms. |
An Evaluation of Laminated Side Window Glass Performance During Rollover | In this study, the occupant containment characteristics of automotive laminated safety glass in side window applications was evaluated through two full-scale, full-vehicle dolly rollover crash tests. The dolly rollover crash tests were performed on sport utility vehicles equipped with heat-strengthened laminated safety glass in the side windows in order to: (1) evaluate the capacity of laminated side window safety glass to contain unrestrained occupants during rollover, (2) analyze the kinematics associated with unrestrained occupants during glazing interaction and ejection, and (3) to identify laminated side window safety glass failure modes. Dolly rollovers were performed on a 1998 Ford Expedition and a 2004 Volvo XC90 at a nominal speed of 43 mph, with unbelted Hybrid II Anthropomorphic Test Devices (ATDs) positioned in the outboard seating positions. Vehicle dynamics, occupant kinematics, and glazing failure modes were evaluated through: on-board instrumentation, analysis of on-board and off-board high speed video and film, a survey of the evidence in the rollover debris field, and post-test inspection of the vehicle, ATDs, and glazing. Laminated side window safety glass did not prevent complete ejection of the ATDs. Five of the six ATDs in the Expedition were completely ejected from the vehicle, and 3 of the 4 ATDs were fully ejected in the XC90 test. Containment of the two ATDs that were not completely ejected was unrelated to glazing contact; the laminated window adjacent to each ATD vacated the window opening and both were partially ejected during the roll sequence. Side window glass fracture and failure was observed in association with ATD loading, ground contact deformation, and combinations thereof. On the basis of the performance observed in this study, it is concluded that heat-strengthened trilaminate glass is not a suitable candidate for occupant containment during rollover. Comparison of these full-scale rollover tests to prior laboratory-based evaluations of laminated side glass demonstrates that the prior studies fail to account for several aspects of the rollover environment, which contribute significantly to glazing loading, fracture, and failure. |
CFD-based Modelling of Flow Conditions Capable of Inducing Hood Flutter | This paper presents a methodology for simulating Fluid Structure Interaction (FSI) for a typical vehicle bonnet (hood) under a range of onset flow conditions. The hood was chosen for this study, as it is one of the panels most prone to vibration; particularly given the trend to make vehicle panels lighter. Among the worst-case scenarios for inducing vibration is a panel being subjected to turbulent flow from vehicle wakes, and the sudden peak loads caused by emerging from a vehicle wake. This last case is typical of a passing manoeuvre, with the vehicle suddenly transitioning from being immersed in the wake of the leading vehicle, to being fully exposed to the free-stream flow. The transient flowfield was simulated for a range of onset flow conditions that could potentially be experienced on the open road, which may cause substantial vibration of susceptible vehicle panels. As these conditions cannot generally be replicated in the wind tunnel, a comprehensive numerical simulation methodology is required if this issue is to be addressed before vehicle prototypes are built. Transient aerodynamic simulations were performed using a Lattice-Boltzmann Method (LBM) and several different approaches were used to create dynamic onset flow conditions approaching the vehicle, such as simulating a: instantaneous transition to a twenty-degree yaw crosswind; twenty-degree harmonic yaw at 10 Hz; flow behind a ?쁞luff body??turbulence generating grid; ?쁯assing disturbance?? vehicle in the wake of another vehicle, at a range of separation distances. A structural solver was used to predict the amplitude of vibration of the hood under these flow conditions. The amplitude response was largest when the frequency content of the oncoming flow matched the natural frequencies of the hood; the turbulence grid was found to produce the largest vibration for this reason. This study shows that transient aerodynamics simulation coupled with a structural solver can be used to predict the onset of vibration for different flow conditions, which could be encountered on the road but cannot be easily reproduced in the wind tunnel. |
Validation of Interior Noise Prediction Obtained using Statistical Energy Analysis and Fast Multipole BEM | Statistical Energy Analysis (SEA) is an effective tool for evaluating the acoustic performance of a vehicle structure and sound package. SEA is typically used to predict both interior noise levels and to set noise reduction targets for various components. A typical full vehicle SEA model includes acoustic loads from airborne sources such as engine, tire and exhaust noise [1]. Each source is typically spatially compact (for example, a tire contact patch) but the source radiates sound that then propagates across the entire exterior surface of the vehicle. In order to characterize a source it is therefore necessary to know both the sound pressure level in the vicinity of the source and also the way in which sound from the source diffracts around the vehicle. A companion paper has investigated the numerical prediction of the diffraction of acoustic sources around a vehicle using the Fast Multipole Boundary Element Method [2]. In this paper, the exterior loads predicted by the FMM BEM method are applied to a full vehicle SEA model and used to predict the interior noise within the vehicle. The results are compared with experimental measurements and good agreement is observed. Modeling guidelines and assumptions are presented and discussed. |
Development of Sound Source Search Technology for High Frequency Noise in Vehicle Interiors | Continuously variable transmission (CVT) and hybrid systems, which have metal belts and electrical units not found in conventional transmissions, are susceptible to extremely High Frequency belt and electromagnetic noise between 5 to 10 kHz. The evaluation and reduction of high frequency (HF) noise of 5 kHz and more is therefore a critical point for improving the quietness of vehicles installed with such systems. This article describes new sound source search technology capable of identifying sources of noise up to 15 kHz in the vehicle interior. Unlike conventional beamforming methods, this new system uses an improved microphone array provided with additional acoustic material. This article outlines the development of the system and its application to sound source identification of HF noise in a hybrid vehicle. |
Why Thermoplastic Door Hardware Systems Make Economic Sense Now | Engineering thermoplastics are widely used in a variety of automotive components systems because of their excellent balance of mechanical performance, design flexibility, aesthetics, parts integration, and low specific gravity. This combination of properties allows for the creation of highly integrated modules, which can increase assembly efficiency and reduce mass, part count, warranty and ergonomic issues, and systems costs. As a result, the use of engineering thermoplastic materials can enhance market competitiveness at a time of increased global competition. To evaluate the economic advantages of polymers in a specific vehicle system, a design for assembly (DFA) case study was conducted with the goal of determining the variable system cost case for a generic thermoplastic door module system vs. conventional-build door systems based on assembly savings gains. This paper will describe the study and show the results achieved. |
An Alternative Approach to Robust Design: A Vehicle Door Sealing System Example | Designing a high-quality door sealing system at low cost is an economic and technological engineering challenge. Robust design is a systematic and efficient technique to meet this challenge of design optimization for performance, quality, and cost. This technique, also called parameter design, focuses on making product and process designs insensitive (i.e. robust) to hard-to-control variations called noise factors. In this paper, we illustrate and apply the principles of robust design using a response model approach to a door sealing system design problem where vehicle interior sound is the primary response being studied. The Appendix contains a glossary of all italicized words for reference. |
Measurement of Transient Vibrational Power Flow in a Car Door Panel Using Intensity Technique | In a structure, the noise source does not always coincide with the origin of excitation. Vibrational energy is transmitted in the structure and noise is radiated from the surface. For noise and vibration control in beam or shell structures, it is important to clearly identify the excitation sources and vibrational energy transmission characteristics. In this paper, measurement of transient vibrational power flow in a car door excited by impact using the envelope vibration Intensity technique is described. Vibrational power flow caused by flexural vibration in the car door panel is measured with the three channel method. The vibrational power flow is expressed with vibration intensity vectors at each measuring point. Instantaneous distributions of measured vibration intensity vectors in the car door panel are shown in this paper. Temporal and spatial variations of the vibrational power flow are discussed. |
Use of FCRASH in a Door Openability Simulation | During frontal and rear end type collisions, very large forces will be imparted to the passenger compartment by the collapse of either front or rear structures. NCAP tests conducted by NHTSA involve, among other things, a door openability test after barrier impact. This means that the plastic/irreversible deformations of door openings should be kept to a minimum. Thus, the structural members constituting the door opening must operate during frontal and rear impact near the elastic limit of the material. Increasing the size of a structural member, provided the packaging considerations permit it, may prove to be counter productive, since it may lead to premature local buckling and possible collapse of the member. With the current trend towards lighter vehicles, recourse to heavier gages is also counterproductive and therefore a determination of an optimum compartment structure may require a number of design iterations. In this article, FEA is used to simulate front side door behavior. Ford guidelines require the side doors, hatches and lift gates to be designed to remain closed during 35 mph perpendicular front (fixed) barrier crash tests. These guidelines also require the side doors to be designed to be capable of being opened without tools after the impact. While earlier analytical techniques [2] to handle door openability were based on door aperture deformation computations, this work describes a technique that is based on more realistic approach which directly simulates the process of door openability itself, using a finite element simulation. Therefore, it enables the simulation of an actual door behavior during and after perpendicular fixed barrier impacts. |
Development of a Door Test Facility for Implementing the Door Component Test Methodology | This paper describes the development of an automated Door Test Facility for implementing the Door Component Test Methodology for side impact analysis. The automated targeting and loading of the door inner/trim panels with Side Impact Dummy (SID) ribcage, pelvis, and leg rams will greatly improve its test-to-test repeatability and expedite door/trim/armrest development/evaluation for verification with the dynamic side impact test of FMVSS 214 (Occupant Side Impact Protection). This test facility, which is capable of evaluating up to four (4) doors per day, provides a quick evaluation of door systems. The results generated from this test methodology provide accurate input data necessary for a MADYMO Side Impact Simulation Model. The test procedure and simulation results will be discussed. Other features and advantages of the automated Door Test Facility are: elimination of ?쐁ut and weld??of structural braces of the old process accommodation of passenger car and light truck doors through a wide range of SID rams ?쐓eating??adjustments synchronization of SID rams movement and loading rate ?쐄reezing??the forward movement of ?쐀ottomed-out??SID ram(s) to maintain constant force to prevent trim panel spring back automated retraction of SID rams upon test completion. |
Glazing Effects of Door or Deformations in Crashes, Part 2 | The non-uniformity of temper of 27 motor vehicle door windows as measured by the polarization method is presented, illustrated by two photographs of windows between crossed polarizers. The tempered glass fracture characteristics of 11 Geo Prism door windows are illustrated by two video frames of the windows after fracturing by door deformation slowly applied at bumper level. The speed of some moderate sized fragments was measured to exceed 60 km/h, due to strain relief rather than contact by an intruding object. Glazing history is briefly summarized, with our support of the NHTSA conclusion that more than 1300 lives per year could be saved cost effectively by replacing tempered glass by an ?쏿dvanced glazing.??
Pressure Fluctuations in a Flow-Excited Door Gap Cavity Model,The flow-induced pressure fluctuations in a door gap cavity model were investigated experimentally using a quiet wind tunnel facility. The cavity cross-section dimensions were typical of road vehicle door cavities |
Experimental Development of a Unique Door Cavity Sound Absorber | Airborne sound traveling through vehicle doors was a significant source of unwanted noise entering the passenger compartment of Saturn vehicles. To reduce these sound pressure levels, several different noise controls were assessed using nonstandard acoustical tests. The noise controls tested include door trim absorbers, barrier watershields, and various noise controls applied in the door cavity. Only when the noise controls were applied in the door cavity were significant noise reductions seen. The final developed part for use in the door cavity further enhanced noise reduction by using a combination of sound absorption and sound transmission loss. |
High Strain-Rate Tensile Testing of Door Trim Materials | The objective of this study was to determine dynamic tensile characteristics of various door trim materials and to recommend a practical test methodology. In this study, Polypropylene (PP) and Acrilonitryl Butadiene Styrene (ABS) door trim materials were tested. Slow speed (quasi-static-0.021 mm/s) and high speed tests were conducted on a closed loop servo-hydraulic MTS system. The maximum stress of these materials increased from quasi-static to dynamic test conditions (as much as 100%). The dynamic stiffness of PP increased two times from quasi-static tests. No significant change in stiffness was observed for ABS during quasi-static and dynamic tests at different strain-rates. Quasi-static and medium strain-rate (10-20 mm/mm/s) tests may be adequate in providing data for characterizing the dynamic behavior of trim materials for CAE applications. Strain gages can be used to measure the quasi-static and in some cases, dynamic strain. Strain gage effect on material properties can be assessed by comparing the maximum stress from tests with and without strain gages. |
Sound Power Measurement in a Semi-Reverberant, Volume Deficient Chamber | Sound power can be determined using a variety of methods, but precision methods require the volume of the noise source to be less than 1% of the chamber volume leading to relatively large test chambers. Automotive torque converter performance and noise testing is completed in an enclosed metallic test fixture which inhibits the use of precision methods due to volume and space limitations. This paper describes a new method developed to accurately determine sound power of an automotive torque converter in a relatively small enclosure through characterization of the test environment. The test environment was characterized using two reference noise sources designed to represent torque converter noise output and physical geometry. Sound pressure levels of the sources were measured at multiple microphone locations and at three source amplitude levels to characterize the environment. Test results were analyzed statistically to determine the microphone positions that best represent the overall sound levels in the chamber. Optimum measurement positions were found to depend on source size but independent of source amplitude. Accuracy was determined based on the variance between the sound pressure levels at each microphone position. Sound power correction factors were found using sources of known sound power and the optimum microphone positions. The new method allows estimation of sound power of operational torque converters in a dynamometer test fixture. |
Acoustic Diagnostic Network Algorithms, their Description and Implementation from Concept into a Comprehensive Vehicle Optimization Program. | Acoustic Diagnostic Network Algorithms (DNA) are experimental methods that extract airborne acoustic characteristics from a motor vehicle and decompose this information into a set of networks from which the source, path and receiver noise sources and paths can be determined. Unlike traditional transfer path analysis Acoustic DNA takes the problem into the fine detail. It answers questions such as what, where and how does a vehicle's acoustic systems need to be changed in order to achieve any given objective. This paper describes the fundamental methodology and features together with how it has been implemented into a computer program that has been used successfully in over 50 vehicle projects within the Authors Research and Development group on a wide range of motor vehicles. |
Understanding the aeroacoustic noise mechanisms and noise control techniques of roof rack systems | Aeroacoustics is one of the top NVH concerns in the automotive industry. HEV/EV have increased the challenge in rebalancing wind noise, and SDC is pushing sound quality requirements to be significantly more demanding than they are in conventional ICE manually-driven vehicles. The most severe aeroacoustic phenomena in ground vehicles are the ones with a tonal nature. Roof rack systems are directly exposed to the airflow and generate broadband noise and a discrete aeolian tone. Typical crossbar profiles are variations over an elliptical profile, i.e. not as blunt as a circular cylinder, neither as thin as a wing section, and a particular solution optimized for one profile will prove less effective in different designs. Therefore, the objective of this project is to investigate the noise mechanisms involved in elliptical crossbars through actual acoustic measurements taken on track. The first part of the project correlated exterior acoustic pressure and intensity measurements taken on track and in an aeroacoustic wind tunnel with the objective of assessing accuracy and repeatability. Exterior sound pressure on-track has demonstrated good accuracy in capturing both narrow and broadband noise effects, despite the uncontrolled background noise. The crossbar wake interaction with the roof plane was investigated through local flow visualization and reference aeroacoustic measurements. The second part of the project compared the noise generated by an elliptical cylinder with that generated by a circular cylinder and a NACA 0012 airfoil with the same thicknesses and at the same operational conditions. Results have shown that the elliptical crossbar noise characteristics have similarities when compared to those of blunt bodies at low Reynolds numbers and wing sections at higher speeds. Different leading and trailing edge geometries demonstrated that the trailing edge is the key contributor to the aeolian tone, while the leading edge affects primarily the broadband noise. Noise control techniques such as Angle of Attack and two and three-dimensional Boundary Layer Tripping (BLT) were investigated. Positive and negative incidence angles presented opposite trends towards noise reduction and have proven to be ineffective at higher speeds. 2D and 3D BLT did not eliminate the main tone but reduced its amplitude and bandwidth. 3D BLT techniques have demonstrated an advantage over 2D BLT. Innovative solutions such as Perforation and active Trailing Edge Blowing (TEB) were assessed. Both Perforation and TEB were effective in reducing the aeolian tone but presented side effects such as high frequency whistling, thus requiring further geometric optimization. |
Instructions for New Projects and Validation Guidelines of Tonneau Covers for Pickup Truck Bed | The purpose of this paper is to suggest guidelines for new projects of soft tonneau covers for pickup truck beds made up of aluminum framework and soft coverage. As the main objective, this paper will make an overall about new accessories projects focusing on each one of the main components of the assembly. The target is to obtain a low cost tonneau cover with a great performance regarding functionality, water accumulation, sealing, noise, robustness, vibration and compatibility with another pick up box's accessories. This article also explores basic procedures for testing and validation of a new soft tonneau covers or a carry over one, with its use extended to a different pickup truck. It is one of the first technical documents about truck soft tonneau covers available, so few references could be found in technical databases. Into this scenario, this article had the objective of give an overall about the subject, offering basic information for new developments and being a start point for future and in-depth studies about this truck component. |
CAA Application to Automobile Wind Throb Prevention Design | When a window opens to provide the occupant with fresh air flow while driving, wind throb problems may develop along with it. This work focuses on an analytical approach to address the wind throb issue for passenger vehicles when a front window or sunroof is open. The first case of this paper pertains to the front window throb issue for the current Ford Escape. Early in a program stage, CAA (Computational Aeroacoustics) analysis predicted that the wind throb level exceeded the program wind throb target. When a prototype vehicle became available, the wind tunnel test confirmed the much earlier analytical result. In an attempt to resolve this issue, the efforts focused on a design proposal to implement a wind spoiler on the side mirror sail, with the spoiler dimension only 6 millimeters in height. This work showed that the full vehicle CAA analysis could capture the impact of this tiny geometry variation on the wind throb level inside the vehicle cabin. The independent wind tunnel effort came to the same conclusion, and the difference between the analysis and testing is only about 1 dB. With the implementation of this spoiler, the program target was finally met. The second case of this paper deals with the sunroof throb issue for an SUV. The work concentrates on the modeling method of wind deflectors made of meshed fabric material and carrying out CAA analysis to access the sunroof wind throb level. The result shows that CAA can predict very well the impact of the wind deflector made of meshed fabric material on the wind throb level, in line with the subjective evaluation on proving ground. In summary, this work manifests that CAA is a very effective tool for wind throb prevention design when hardware prototypes are not available. |
Custom Configuration of a Vehicle Electrical Control System for Production and Service | International Truck Engineering has incorporated a cab electrical system controller (ESC) into their vehicle design. This was done to facilitate a larger number of configurations with a simpler hardware design. The ESC makes use of SAE J1939 and J1708 to communicate with instrument cluster, door, power train and other modules. It also has various discrete inputs and outputs. A proprietary operating program written for the ESC uses a set of binary configuration structures stored in flash ROM and includes a proprietary ?쐀yte code??interpreter. The configuration describes how to process all I/O signals to/from a central data array, byte code to execute and the instrument cluster layout. Byte code operates on the data array between input and output processing. The switches and gauges in the instrument cluster plug into network modules. Due to the variability of the International Truck & Engine vehicle products, the content of the ESC configuration can vary widely from vehicle to vehicle. It is the IT (Information Technology) organization's task to provide a specific configuration for each ESC. Based on customer ordered features, the configuration must contain the proper byte code modules, I/O processing and cluster configuration information. IT must also select the proper switches, gauges and warning lights and their locations, as well as match the discrete I/O to signals on pre-existing wiring harnesses. The software and hardware included in the configuration must be validated to prevent software and hardware conflicts. In addition to the initial configuration, IT must also provide vehicle service support. This includes reconfiguration of the ESC for software updates, recall support and customer driven additions or modifications. The system that IT developed to solve these issues is discussed. |
Closed-Loop Recycling of Monomaterial Door-Panel Systems | Pressures to increase the recyclable and recycled content of passenger vehicles are accelerating. In Europe, there is interest in eliminating halogenated polymers. Globally, more and more concern is focused on materials and methods that are ecologically friendly. Automakers and their suppliers are being encouraged to design and assemble components in new ways to facilitate separation, identification, and resource recovery at the end of the vehicle?셲 useful life - something that is not only good for the environment, but also the bottom line. One area of the vehicle that has proved challenging for applying such design for disassembly and recycling (DFD/R) principles has been the interior, owing to the sheer number of materials used there, and the great number of laminate structures that make disassembly nearly impossible. A good example is a door panel inner, which typically consists of a rigid plastic substrate, a foam pad, and a vinyl, leather, or cloth covering. This component is usually comprised of different materials tied with adhesives and polyester scrim fabrics. Fortunately, recent material developments as well as process enhancements have now made it possible to quickly and efficiently manufacture all-olefin door panels without adhesives or scrim, making the monomaterial door panels excellent candidates for recycling. But how recyclable are these systems? A recent manufacturing study successfully recycled fully covered door-trim panels comprised of an olefin-based coverstock, a cross-linked olefin foam pad, and a polypropylene (PP) substrate. Processing scrap was chopped and reintroduced - at predetermined weight ratios - back into the virgin resin feedstream used to produce additional PP door substrates. A variety of tests were performed both on plaques and full door panels comprised of varying ratios of virgin + recycled material to see if the presence of the recycled material affected any physical or mechanical properties, processability, or other engineering specifications. The results of this testing program are presented here, along with recommendations for implementing a closed-loop recycling program. |
An Integrated Automobile Keyless Operation System | An integrated automobile keyless operation system is developed. The system consolidates the ignition key and lock/switch, security and keyless entry and other functions into one unit. The system uses a small handheld portable wireless remote controller to replace the ignition key, the door key and the trunk key. A receiver replaces the ignition switch and functions as controlling switches for door-locks and/or trunk-lock. The system incorporates the latest advancement in wireless technologies and digital-signal processing. By consolidating components, the design cuts manufacturing cost, improves reliability and offers outstanding convenience and enhanced security. |
Sensory Evaluation of Commercial Truck Interiors | Vehicle interior harmony is related to human factors but it deals with human emotional attachment to the product. Kansei, or sensory engineering provides an effective approach to address harmony issues. This paper reports a preliminary investigation of human sensory evaluation of commercial truck interiors, especially the door interiors. To investigate the end users' needs and preference, a questionnaire survey was administered to twenty-six commercial truck drivers. Responses on usability, styling, harmony, and ergonomics issues of each driver's own truck were recorded. Furthermore, a set of 12 semantic differential scales, together with a preference ranking scale, was served to evaluate six truck door interiors. Results show that commercial truck drivers are more concerned with functionality and usability than styling and visual harmony. However, concerns on interior styling and harmony represent more than one-third of the design issues reported by the participants, indicating that interior harmony issues should not be overlooked. Three factors of door interior visual harmony were identified: color and emotion, geometric shape, and spatial arrangement. The color and emotion factor showed a high correlation with preference ranking merit value. Future work will be carried out to associate principal harmony factors with design parameters of door interiors. |
Foresight Vehicle: Large Area Flexible Circuits for Automotive Applications Manufacturing Technology - A Review of Process Options | It is the intention of motor vehicle manufacturers to achieve weight and cost savings by replacing wiring harnesses with flexible printed circuits in doors, roof liners, boots and cockpits. These circuits will be required in high volume and must meet the requirements of the vehicle and equipment suppliers with respect to cost effectiveness and reliability while presenting an achievable, economically sound manufacturing technology to the circuit suppliers. Design issues include requirements for CAN-bus1, EMC/RFI protection, 42 volt systems and the integration of functional modules 2,3,4. Alternative construction options and criteria for their assessment are proposed. The range of processes from which a manufacturing technology can be established are identified and discussed. The challenges presented to available processes and equipment by the potentially very large circuits are examined. |
A Development Procedure to Improve the Acoustical Performance of a Dash System | This paper discusses a development procedure that was used to evaluate the acoustical performance of one type of dashpanel construction over another type for a given application. Two very different constructions of dashpanels, one made out of plain steel and one made out of laminated steel, were studied under a series of different test conditions to understand which one performs better, and then to evaluate how to improve the overall performance of the inferior dashpanel for a given application. The poorly performing dashpanel was extensively tested with dashmat and different passthroughs to understand the acoustic strength of different passthroughs, to understand how passthroughs affect the overall performance of the dash system, and subsequently to understand how the performance can be improved by improving one of the passthroughs. |
Massive Point Cloud Data Sets and Single Point Measurement Acquisition in the Production Floor Environment | In typical production lines of automotive manufacturers, body parts are produced every several minutes. Sample parts are measured at certain intervals with a CMM machine at approximately 30 points to verify correct production. The points measured on each sample part are compared with reference points of a golden part or with the CAD model. This paper presents results achieved with a high-accuracy non-contact 3D measurement system capable of measuring both the full surface of sample parts and surface points (surface point measurement, or SPM), after production, on the production floor. The technology used enables high-speed image acquisition of large data sets together with CMM-like capability of measuring individual points, both accomplished simultaneously. SPM measurement of a car door requires approximately 15 minutes; measurement of a full door surface, including SPM, requires less than 1 hour if operated manually, or alternatively 3 minutes for SPM and approximately 10 minutes for full surface measurement if performed by a robot-based system. The system is capable of measuring shiny, oily and/or dirty parts, which makes it suitable for measurement right on the production floor. The resulting surfaces and points measured are aligned to vehicle coordinates by the system, and compared to the CAD design. SPMs are compared to their reference points, and reports are exportable. Examples of series of COP/CAD comparisons will be presented, taken on the production floor, illustrating the gradual development of a production defect and its detection with the full surface data. Such defects can immediately be found, when measuring the entire surface of each part, during production (in process). Corrective action can be taken before inaccuracies get out of control. |
A Method to Determine the Power Input Associated with Rain Excitation for SEA Models | Statistical Energy Analysis is used to predict the sound pressure level (SPL) in the interior of the vehicle. This is accomplished by knowing the energy sources (tire, engine, wind, etc) affecting the interior as well as the acoustic performance (absorption and transmission loss) of the interior trim components (headliner, door panels, instrument panel, etc). One of the noise sources that has not been seriously examined to-date is panel excitation by precipitation. The excitation of the roof due to raindrops can be a major noise source. Knowing how to properly model this power input would help analyze different headliners or roof treatments to minimize the SPL in the interior cavity. This will involve computational determination of mass, speed, and energy of standard water droplets for one of rain condition. A power spectrum is presented for one rain intensity condition on a test fixture. |
E-Modularization of Rear Closures: Integration of New Generation of Electrical Systems | This paper presents the potential for rear closure submodules. Side door modules and lightweight rear closures have attracted a lot of attention in recent years. However the characteristics of future liftgates allow the design of specific mechatronic sub-modules (e-modulesTM). Beside structure, rear closures satisfy three main functions: rear vision, rear signaling and rear access. All are undergoing a generation change that will be outlined in the first part of this paper, system by system. Each time the rationale behind modular integration, whether electronic or mechanical, will be reviewed. The second part presents examples of e-modulesTM that illustrate the potential gains in terms of ease of assembly, packaging optimization and network integration. |
Development of Composite Body Panels for a Lightweight Vehicle | Recently weight reduction is increasingly needed in automotive industry to improve fuel efficiency and to meet a CO2 emission requirement. In this paper, we prepared composite body panels for the lightweight vehicle based on a small passenger car. Fender, roof, door, side outer panel, and tailgate are made from hand layup using a glass/carbon hybrid reinforcement. Hood is made from low pressure sheet molding compound (SMC) to investigate feasibility of mass production. Both hand layup and low pressure SMC materials are newly developed and their physical properties are examined. CAE simulation was done for strength analysis and optimization of thickness for the body panels. |
A New Wavelet Technique for Transient Sound Visualization and Application to Automotive Door Closing Events | Transient automotive sounds often possess a complex internal structure resulting from one or more impacts combined with mechanical and acoustic cavity resonances. This structure can be revealed by a new technique for obtaining translation-invariant scalograms from orthogonal discrete wavelet transforms. These scalograms are particularly well suited to the visualization of complex sound transients which span a wide dynamic range in time (ms to s) and frequency (??00Hz to ??0kHz). As examples, scalograms and spectrograms of door latch closing events from a variety of automotive platforms are discussed and compared in light of the subjective rankings of the sounds. |
Percentile Frequency Method for Evaluating Impulsive Sounds | The Percentile Frequency method originated in an attempt to quantify the frequency content of door slam sounds. The method is based on the Specific Loudness Patterns of Zwicker Loudness. Zwicker states that the area of the Specific Loudness Pattern is proportional to the total loudness. The method summarizes each Pattern as seven frequencies identifying the contributions of fixed percentages of the total area (i.e. 10%, 20%, 30%, 50%, 70%, 80% and 90%). Applying the method to each Pattern in a time series generates a family of curves representing the change in relative frequency content with time. The process, in effect, normalizes the frequency content of the impulse for loudness and reduces the data to a two dimensional plot. On a Percentile Frequency plot a simple impulse appears as a pattern of ?쐍ested, inverted check marks.??More complicated impulses, such as rattles, have more complicated shapes that are still ?쐍ested??together. Applying this understanding to practical problems, the method has been used to visually show the progress of a project to reduce rattles occurring in door slam sounds. The method also has been used to quantify the low pitched ?쐔hump??of a door slam sound. In addition, a further extension of the method has been successful in differentiating high pitched door latch closing sounds. By incorporating these techniques into a general door slam sound test, it should be possible to evaluate objectively for rattles, latch sound, and ?쐔hump??as well as loudness. |
Door System Design for Improved Closure Sound Quality | Door closing sounds are an important element of the craftsmanship image of a vehicle. This paper examines the relationship between closure sound quality and door system design. The perception of door closing sound quality is shown to be primarily related to it's loudness and sharpness. Of the two, sharpness is more important than loudness. Other factors, like ring-down may also affect closure sound quality. The door system is made up of a number of components. The most important in terms of sound quality are the door and body structure, latch, and door seals. Each of these are classified as either a sound source, a transmission path or a sound radiator. Methods for improving the design of these components for good closure sound quality are discussed in some detail. |
A Study on The Hybrid Finite Element Modeling for Side Impact Simulation | In this study we suggest simplified and design oriented hybrid modeling methodology to the development of crashworthy structure. This hybrid model consists of main structure, which are modeled by beam and springs and doors modeled by shells. The main structures such as B-pillar roof rail and side sill are represented by nonlinear springs which have the same section properties as shell model have. The localized collapse of main structures are represented by non-linear spring elements whose moment-rotation characteristic is calculated based on Wierzbicki?셲 equation. The joint parts are represented by non-linear springs, which have the same moment-rotation characteristics as those of real parts to hold actual collapse characteristics. To represent force transition between structure and door, anti-sliding shells are introduced in the area of side-sill and lower part of Bpillar. Using this hybrid modeling methodology, we can get a good correlated result for full model and reduce calculation times around 80% for full FE shell model. |
CFD Simulation of Side Glass Surface Noise Spectra for a Bluff SUV | Simulation of local flow structures in the A-pillar/side glass region of bluff SUV geometries, typical of Land Rover vehicles, presents a considerable challenge. Features such as relatively tight A-pillar radii and upright windscreens produce flows that are difficult to simulate. However, the usefulness of aerodynamics simulations in the early assessment of wind noise depends particularly on the local accuracy obtained in this region. This paper extends work previously published by the author(1) with additional data and analysis. An extended review of the relevant published literature is also provided. Then the degree to which a commercial Lattice-Boltzman solver (Exa PowerFLOW?? is currently able to capture both the local flow structure and surface pressure distribution (both time averaged and unsteady) is evaluated. Influential factors in the simulation are shown to be spatial resolution, turbulence and boundary layer modelling. It is demonstrated that, whilst reasonable predictions are obtained for the surface noise spectra, both the size and strength of the A-pillar vortex are substantially over-predicted. Finally an attempt is made to estimate the frequency range that the simulation could be reasonably expected to capture. This analysis suggests that the simulation is bounded by the limitations of the turbulence model, rather than spatial resolution. |
Low-Cost Audio for Automobiles | Much design effort is given to the development and tuning of high-end automotive audio systems. Typically, premium speakers, separate amplifiers and careful tunings are used to create very high audio performance levels. Lower cost vehicles and vehicles of lower trim levels often feature more ordinary speakers and no separate amplifier. This typically leaves a number of listeners with little option for enjoying adequate bass performance, improved stereo imaging, etc. Small changes in acoustical component features and specifications can produce significant returns in spectral performance. Additionally, low-cost, powerful audio digital signal processing (DSP) has made its way into modern receivers. As the processing power of these devices improves, there are new opportunities for lower-level vehicles to produce customer-pleasing levels of audio performance. This paper addresses issues facing designers of lower-end audio systems and proposes solutions for potentially vexing problems such as those caused by non-linear speaker excursion. Informal listening test results from expert and non-expert listeners are also included. |
Study and Application of Prediction Method for Low Frequency Road Noise | When a vehicle drives over road seams or a bumpy surface, low-frequency noise called drumming is generated, causing driver discomfort. The generation of drumming noise is closely related to the vibration characteristics of the suspension, body frame, and body panels, as well as the acoustic characteristics of the vehicle interior. It is therefore difficult to take measures to get rid of drumming after the basic vehicle construction has been finalized. Aiming to ensure drumming performance in the drawing review phase, we applied the Finite Element Method (FEM) to obtain acoustical transfer functions of the body, and Multi Body Simulation to get suspension load characteristics. This paper presents the results of the study of drumming prediction technology using this hybrid approach. The paper also describes the results of 1) analyzing actual driving behavior when drumming occurs using a multi-point simultaneous measuring system, 2) analyzing suspension vibration characteristics as a cause of drumming, and 3) validating the correlation between the FEM model and an actual vehicle using Robot-controlled 3D Scanning Laser Vibrometers. Modifications made to the actual body structure are also introduced as a case study on effective drumming reduction. |
An Iterative Approach Based on Prony's Method to Calculate the Surface Impedance of Acoustic Materials Measured in situ | In many cases the in situ measurement of the absorption coefficient requires an iterative method for the correct calculation of the surface impedance of a sample. This happens because when spherical waves reflect on a sample's surface the pressure field above it is a function of the sample's surface impedance. As the pressure field involves an integral term, numerical integration is required in the iterative algorithm, which can be time consuming. The aim of this paper is to present an iterative approach based on Pony's method, which instead of numerical integration uses a series expansion with a few terms. Therefore the time of processing is decreased. Besides the description of the method, simulations and measurements (with a p-u probe inside an office room and a car) are presented. A comparison, with numerical integration, regarding the accuracy and the time of processing of Pony's method is also discussed. |
Auditory Localization of Backup Alarms: The Effects of Alarm Mounting Location | Sound localization of a backup alarm is important in situations when vehicles are reversing. Previous work has demonstrated the effects of ambient noise level and the spectral content of the backup alarm on localization. In the current study, we investigate the effects of backup alarm mounting location on localization performance. To address this question, we asked blindfolded listeners to localize backup alarms installed in positions that provided either direct (e.g., installed on the outer rear aspect of the vehicle) or indirect (e.g., installed within the inner frame rails of the vehicle) sound propagation paths to the listener. Additionally, we explored the effects of ambient noise level and the direction of origin of the alarm (behind, in front of, or to the left or right of the listener), and the interactions among all three factors (alarm location, ambient noise, and alarm direction relative to the listener). Localization performance was examined in terms of percent correct localization, as well as percent front-back confusion errors. When the alarm stimuli were presented in front, the alarm that was mounted directly in front of the listener -- providing a direct path to the listener --produced more correct localizations than the other alarms. This direct-path alarm also resulted in the least front-back confusions overall. However, when the alarm stimuli were presented behind the listener, the alarm mounted at the top of the rear of the truck --providing a direct but elevated path to the listener -- produced the worst performance and the most front-back confusion errors. An important factor affecting listeners' localization performance was the orientation of the listener relative to the direction from which the alarm stimuli originated. When the alarm was to the right or left of the listener, all alarm mounting locations produced equally good performance and no front-back confusions. Alarms originating from behind the listener, however, generally produced the worst performance, and the most front-back confusions, for the majority of the alarm mounting locations. |
Efficient CFD Simulation Process for Aeroacoustic Driven Design | The transport industries face a continuing demand from customers and regulators to improve the acoustic performance of their products: reduce noise heard by passengers and passersby; avoid exciting structural modes. In both the aerospace and automotive areas, flow-induced noise makes a significant contribution, leading to the desire to understand and optimize it through the use of simulation. Historically, the need for time-consuming, computationally expensive transient simulations has limited the application of CFD in the field of acoustics. In this paper are described efficient simulation processes that, in some instances, remove the requirement for transient analyses, or significantly reduce the total process time through intelligent pre-processing. We will outline this process and provide both automotive and aerospace industrial examples, including analyses of highly complex geometries found in real life. Section 2 describes a modeling hierarchy which includes steady-state, transient and frequency-based time-periodic methodologies. Section 3 contains four popular classes of application spread across the transportation sectors: - Airframe noise simulation of a complex nose landing gear; - Aeroacoustics of avionic cooling rack in an Airbus cockpit; - Automotive sunroof buffeting with structural impedance; - Fan noise signature in the presence of gusts. For these case studies, the main focus is the prediction of aeroacoustic noise sources. The propagation of noise to the far-field is not considered here, though some qualifying comments are made in section 2.4. |
Optimization of Bus Body Based on Vehicle Interior Vibration | In order to solve the abnormal vibration of a light bus, order tracking analysis of finite element simulation and road test was made to identify the vibration source, finding that the rotation angular frequency of the wheels and the first two natural frequency of the body structure overlaps, resonance occurring which lead to increased vibration. To stagger the first two natural frequency and excitation frequency of the body, thickness of sheet metal and skeleton of the body-in-white were chosen as the design variables, rise of the first two natural frequency of the body-in-white as the optimization objective, optimal design and sensitivity analysis of the body-in-white was carried out with the modal analysis theory. Combining with the modal sensitivity and mass sensitivity of sheet metal and skeleton, the optimum design was achieved and tests analysis was conducted. Comparing the test results before and after optimization, the effectiveness and rationality of the optimization is verified. |
Assessment of a Vehicle's Transient Aerodynamic Response | A vehicle on the road encounters an unsteady flow due to turbulence in the natural wind, due to the unsteady wakes of other vehicles and as a result of traversing through the stationary wakes of roadside obstacles. There is increasing concern about potential differences between the steady flow conditions used for development and the transient conditions that occur on the road. This paper seeks to determine if measurements made under steady state conditions can be used to predict the aerodynamic behaviour of a vehicle on road in a gusty environment. The project has included measurements in two full size wind tunnels, including using the Pininfarina TGS, steady-state and transient inlet simulations in Exa Powerflow, and a campaign of testing on-road and on-track. The particular focus of this paper is on steady wind tunnel measurements and on-road tests, representing the most established development environment and the environment experienced by the customer, respectively. Measurements of the surface pressure on the front sideglass were used for comparisons as this area exhibits a complex flow which is highly sensitive to yaw angle and which is also an important region, for wind noise considerations in particular. It was found that, if the transient on-road environment is known then steady-state wind tunnel measurements can be used to predict accurately the transient surface pressures, provided the methodology is sufficiently rigorous. Admittance or transfer function techniques are commonly used to compare transient and steady-state results and the limitations of these methods are shown here when the spectra of self-excited and externally imposed unsteadiness overlap. A new method is introduced to obtain a ?쐔rue??transfer or admittance function, unconfused by the presence of self-excited unsteadiness. The aerodynamic admittance was found to be close to unity up to a frequency of 2-10 Hz and it then drops progressively. |
A Comparative Study of Automotive Side Window Occupant Containment Characteristics for Tempered and Laminated Glass | This study investigates occupant containment characteristics of tempered and laminated automotive moveable side glass in rollover collisions. FMVSS 216 test protocols were used to induce roof damage or sheet metal damage around the window opening in Lincoln Navigators equipped with tempered and laminated side glass. Dummy-drop tests were then performed to investigate relative containment. The results demonstrate that, for rollovers in which the window structure is compromised, tempered side glass and laminated side glass perform comparably relative to occupant containment. Also discussed are the general strength characteristics of different types of glass construction, the availability of laminated side glass in recent model U.S. vehicles, and anecdotal data supporting the conclusions of testing. |
On the Use of the Fast Multipole Method for Accurate Automotive Body Panel Acoustic Load Predictions | Knowledge of the external sound field around a car body is critical for vehicle acoustic development. Airborne isolation predictions, and thus panel and trim design depend on this data. Nowadays, such information is the result of experimental methods, as previously investigated simulation solutions proved either too costly, or not precise enough. In this paper, we investigate the use of a method combining computational efficiency and results accuracy: the Fast Multipole Method. This boundary-integral method uses an iterative solver and does not require a full assembly and factorization of the system matrix, thus allowing precise calculations over an extended frequency range even for large objects. In the present study, we demonstrate the potential of the method on a mid-range van, the Renault Scenic. |
SEA Model Development Considerations for Cost-Driven or Developing Market Vehicles | In South America and other developing markets the NVH development of a vehicle is often limited by the cost of the sound package components. In an era where cost reduction is crucial not only in developing markets, but also in developed markets where any cost or weight savings is a large competitive advantage, lessons learned from considerations for NVH analysis for vehicle design in developing markets can be applied to vehicle NVH design everywhere. A Statistical Energy Analysis (SEA) model was used to target and identify the dominant paths in need of sound package modifications to decrease the over sound pressure levels and also to identify paths in which sound package (and cost) could be reduced or deleted with no discernable degradation to the overall interior levels. This model will be used to support or challenge ongoing proposed sound package modifications to the vehicle and serve as a baseline template for design phase work for other vehicles of a similar body style. |
Contribution Analysis of Vehicle Interior Noise Using Air-borne Noise Transfer Function | The efficient insulation of noise transmitted from the powertrain is one of the important issues in developing the variation or minor change of the vehicle. This paper deals with the contribution analysis of each path of interior noise by window mask method using air-borne noise transfer function and shows the application of Taguchi method in finding the best combination of the insulation countermeasures. To this aim, the vehicle interior cabin is segmented into 25 windows and the air-borne noise transfer functions between source and receiver points are measured by acoustic reciprocal method. |
Investigation of Factors Influencing Vehicle Audio Speaker Locations for Better Sound Quality and Spread | The NVH performance of today's automobiles has been improved to levels where common user can easily perceive the issues related to sound quality inside the passenger compartment. With NVH development resulting in quieter and quieter driving conditions, the importance of better acoustic in car-entertainment has been improved by 2-3 notches. The focus of this paper is further concentrated on the methodology to evaluate and optimize speaker location in a MPV. The speaker location was optimized for its location inside passenger compartment and its mounting characteristics. Two different configurations of speaker fitment locations for different seating patterns were tested in vehicle. Frequency Response Function and sound quality parameters were measured experimentally and calculated using sound quality algorithm respectively. The optimal position of speaker location is then determined by analyzing the data for a) uninterrupted reach of the signal to all passenger locations throughout its frequency range. b) Noise contamination of the source because of reflections from nearby interior components. c) Influence of support stiffness on the source contamination. The evaluation methodology was established as a standard practice for using on different vehicles for speaker location optimization. |
Operating Noise Synthesis on a Class 8 Truck Cab | The objective of this work was to synthesize the time and space average operating airborne noise excitation field from discrete noise sources, to the exterior surfaces of a Class 8 truck cab while operating fully loaded at 60 mph. This noise field was subsequently used as input to a statistical energy analysis (SEA) model, for designing a sound package to reduce interior noise. As a relatively simple and inexpensive alternative approach to direct measurements using a heavy-duty chassis dynamometer in a semi-anechoic chamber, the method nevertheless provided an acceptable input for the SEA development work. |
Using the Hybrid FE-SEA Method to Predict Structure-borne Noise Transmission in aTrimmed Automotive Vehicle | A Hybrid method that rigorously couples Statistical Energy Analysis (SEA) and Finite Element Analysis (FEA) has been used to predict interior noise levels in a trimmed vehicle due to broadband structure-borne excitation from 200Hz to 1000Hz. This paper illustrates how the Hybrid FE-SEA technique was applied to successfully predict the car response by partitioning the full vehicle into stiff components described with FE and modally dense components described with SEA. Additionally, it is demonstrated how detailed local FE models can be used to improve SEA descriptions of car panels and couplings. The vibration response of the untrimmed body-in-white is validated against experiments. Next, the radiation efficiency and vibration response of bare and trimmed vehicle panels are compared against reference numerical results. Finally, interior noise levels in bare and trimmed configurations are predicted and results from a noise path contribution analysis are presented. |
CAE Interior Cavity Model Validation using Acoustic Modal Analysis | The ability to predict the interior acoustic sound field in a vehicle is important in order to avoid or to minimize unwanted noise conditions, such as boom or high pressure levels at cavity resonance frequencies. In this work an acoustic modal analysis is carried out for a minivan. The testing procedure is discussed and some results are shown. With the seats removed and for low frequencies the interior of the vehicle is similar to a rectangular box for which an analytical solution exists. At higher frequencies and with the seat, the interior acoustic field displays complex mode shapes. |
Root Cause Identification and Methods of Reducing Rear Window Buffeting Noise | Rear Window Buffeting (RWB) is the low-frequency, high amplitude, sound that occurs in many 4-door vehicles when driven 30-70 mph with one rear window lowered. The goal of this paper is to demonstrate that the mechanisms of RWB are similar to that of sun roof buffeting and to describe the results of several actions suspected in contributing to the severity of RWB. Finally, the results of several experiments are discussed that may lend insight into ways to reduce the severity of this event. A detailed examination of the side airflow patterns of a small Sport Utility Vehicle (SUV) shows these criteria exist on a small SUV, and experiments to modify the SUV airflow pattern to reduce RWB are performed with varying degrees of success. Based on the results of these experiments, design actions are recommended that may result in the reduction of RWB. |
Prediction and Improvement of High Frequency Road Noise of a Mid-Size Sedan | An airborne SEA model to predict high frequency interior noise is built for a mid-size sedan. The 60 KPH running condition is simulated based on this model and then the corresponding result is compared to the measured interior noise. A very similar prediction is found. Also, weak points of sound insulation and effective absorption area in this vehicle are identified using the model. It is shown that in an early design stage and when the proto vehicle is not available yet, the airborne SEA model is very useful to find out weak points of vehicle sound packages. |
Investigation of Gravel Noise Mechanisms and Impact Noise Transfer | Impact noise, inside a car, due to tire-launched gravel on the road can lead to loss of quality perception. Gravel noise is mainly caused by small-sized particles which are too small to be seen on the road by the driver. The investigation focuses on the identification of the mechanisms of excitation and transfer. The spatial distribution of the particles flying from a tire is determined, as well as the probable impact locations on the vehicle body-panels. Finally the relative noise contributions of the body-panels are estimated by adding the panel-to-ear transfer functions. This form of Transfer-Path-Analysis allows vehicle optimization and target setting on the level of the tires, exterior panel treatment and isolation. |
Long-Range Human Body Sensing Modules with Electric Field Sensor | The authors have developed a long range version human body sensing module. This module has a high measurement accuracy with a capacitance of less than two femto Farads and can detect more distant human bodies compared with conventional sensors. Furthermore, optimizing the electrode structure of this module, noise tolerance and directivity have been improved. We produced some prototypes of this sensor module and evaluated the sensitivity of them in a vehicle. The results show that the prototype can detect a hand at the distance of 300 mm from the sensor electrode. |
A Development And Test Environment for Automotive LIN Network | ?쏬IN-BOX??is designed as a development tool for simulation, implementation and test of the automotive LIN (Local Interconnect Network) control devices or entire network. The tool can be used to simulate master and/or slaves around LIN system. The configurable signal processing makes it possible to simulate and test the communication behavior. LIN-BOX monitors the bus traffic in the vehicle. The data on LIN bus can not only be shown on various windows but also written into log files. LIN-BOX has been used by several cases for debugging and validation, the result shows that it is a powerful tool for LIN cluster design, simulation and test. |
Study cases using the method of Statistical Energy Analyse SEA for airborne sound transmission in a vehicle body | The acoustics insulation on the car body is ones of the more important target in the NVH (Noise Vibration and Harshness) vehicle development process. The method of SEA is a validated statistical approach to solve airborne noise transmission problems. In the vehicle analysis above 300 Hz where material trim and leakage paths makes a important contribution in the vehicle interior acoustics shows the methodology its advantages over deterministic methods. |
Sound Quality Engineering of a New Transport Refrigeration Unit | The redesign of a diesel driven transport refrigeration unit is described, with focus on sound quality goals. Acoustic level and quality goals were set with customer feedback based on jury tests. Sound source levels of specific components were identified, with the noise level of the diesel intake and exhaust, the condenser fan, and noise of the gearbox having the most impact on sound quality. A post-design jury test confirmed the effectiveness of the redesign effort. |
Modeling of Firewall Panel with Laminated Metal using Experiment and Numerical Methods | For the automotive industry, the sound quality inside the vehicles is very important. This importance has increased significantly in the last years within the globally competitive automotive market. The interior vibroacoustic behavior depends on the dynamic characteristics of the car body. Several treatments are used to reduce the structural energy of the body panels. For instance, it may be applied passive damping technology, by use of viscoelastic materials, to control their noise and vibrations. This paper presents a comparison of the vibroacoustic characteristics of two firewall panels, made with normal and quiet steel. Experimental and numerical (FEM and BEM) techniques are used to get modal and acoustic data. |
Scan & Listen: a simple and fast method to find sources | The particle velocity field close to a source almost matches the surface vibration whereas the sound pressure field is mainly caused by the background noise. Here a new method is proposed that is to simply listen to the particle velocity field to find sources. The method shows to give a very fast first impression of the acoustic problem at hand. |
Seat/Floor Coupling CAE Study for Body/Vehicle NVH | In today's competitive automobile environment with shorter vehicle development time and fewer prototypes/tests, CAE is becoming very crucial for vehicle development. Seat is a critical system of automobiles for customer satisfaction because seat provides support, safety, and comfort especially NVH for vehicle occupants. In this paper, the effects of seat system on body and vehicle NVH were studied. How the seat system affected body and vehicle NVH, and how seat to floor coupling affected vehicle NVH were investigated. Two groups of finite element body models, body-on-frame and unitized body, were used for this study to ensure the effect of body architecture was included in this study. In the baseline body models, the seats were represented by detailed finite element models. Then, several versions of body models were built by modeling seats in different finite element representations. Three critical vehicle road load cases (engine idle, coarse road at 30mph, and rough road at 40mph) were investigated in this study. Body NVH performance (local/global modes and seat track/floor attachment responses) and vehicle road NVH performance (front/rear interior sound and seat track/floor attachment vibration) of different body versions were assessed against that of baseline models. The conclusions would determine the seat contribution (seat/floor coupling) for body/vehicle NVH performance. The results would also guide the seat modeling methods for body/vehicle NVH CAE analysis. |
NVH Optimization for Passenger Car Thermal Systems | Noise and vibration of passenger car thermal systems are some of the major contributing factors to customer satisfaction. The optimization of these characteristics requires an integrated approach involving detailed analysis, simulation and testing. This paper describes selected noise, vibration and harshness (NVH) issues, discusses solutions and provides examples of its successful applications for thermal systems in passenger cars. The major components of a thermal system include condenser, radiator and fan module, main HVAC module, auxiliary HVAC module as well as air conditioning (AC) additional components such as lines, seals, hoses and vibration isolators. All components can contribute individually or as a system to the noise problem. Significant sound level reductions and improvements in sound quality have been achieved applying detailed analysis, Computer Aided Engineering (CAE) tools, and advanced testing methods. Examples presented in this paper include an auxiliary HVAC module of half the size and equivalent overall sound level compared to past designs, considerable reductions in objectionable noises such as aspirator and defrost bleed noises, and improvements in vibration through optimized placement of stiffening members. |
Integrated Approach and Ideas for Designing Lightweight NVH Parts in Passenger Vehicle | The Interior noise is now one of the signatures of passenger vehicles. It contributes significantly to a customer's perception of quality. The vehicle acoustic package can be an important piece to the acoustic signature, and can be used not only to reduce sound level inside the vehicle but also to shape the sound such that it meets the expectation of customer and increasing competition between the Vehicle Manufacturers. The conflicting objective of maintaining high Noise, Vibration and Harshness (NVH) characteristics at the same time reducing the weight of the vehicle is a major priority within the Automotive Industry. Moreover to meet ever-growing demand to minimize emission and to achieve greater efficiency from automobiles, there has been a constant effort to reduce the weight of the vehicle body structure along with improving NVH of vehicle. This paper reflects various measures used in the new generation automobiles to provide a superior acoustic package to the customer for a quite and pleasant drive along with improving vehicle body structure by means like bead pattern optimization and tailor rolled blank design in terms of weight reduction to give a highly efficient and greener car for creating greater customer satisfaction. |
Application of Acoustic FEA to the Automotive and Aircraft Industry | Numerical simulation techniques are widely used in automotive and aircraft sectors. The optimization of industrial products with respect to acoustic performance requires appropriate modeling strategies in order to handle various noise sources and different propagation paths. The present paper focuses on the application of finite element techniques (FE) to the solution of vibro-acoustic and aero-acoustic problems. State-of-the-art FE techniques are reviewed and illustrated by appropriate examples. |
Difficulties Encountered in the Correlation of Vehicle Response to Bench Testing of Driveline Gearboxes for NVH Attributes | Correlating a bench test stand to predict the response of a driveline gearbox in the vehicle can be very difficult. Many sources of variation and error may prevent correlation. This paper outlines the issues related to both vehicle and bench testing that prevents proper correlation. The importance of understanding both the NVH measurements and statistics are vital to proper interpretation. The identified issues are backed up with real test cases where these issues occurred in a series production gearbox program. A successful correlation case study is presented for comparison. |
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