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Passive Venting for Alleviating Helicopter Tail-Boom Loads | The tail boom of a single-rotor helicopter is subjected to a complex flow field that includes the wakes of the main and tail rotors, the freestream, and the wake from the forward fuselage. Hovering and sideward flight present the operational regimes that are most critical with respect to adverse sideward and downward loads on the tail boom. These adverse loads necessitate additional engine power, thereby reducing payload, performance, and available yaw-control margins. In addition, nonlinear side-force gradients near conditions of boom stall can make precise yaw control very difficult for the pilot. The addition of strakes to the tail boom is one method that has been used to modify the flow field and reduce these adverse loads. |
A Flexible Lateral Seam Riveting System for Circular Aircraft Structures | The need for a flexible and automated seam riveting system has opened the door for a new approach to machine design. The Flexible Lateral Seam Riveting system (FLSR) proposed by Gemcor will be able to automatically, under CNC and tracer control, rivet both lateral and radial joints without the use of dedicated and fixed machine track systems. The FLSR system is adaptable to a wide range of part diameters and configurations with lengths up to 10m (394 inches). Applications include aircraft fuselage sections as well as any other circular section which is assembled with rivets or other standard aerospace fastener systems including interference fit type. |
Study on Test and Product Variations of Noise Reduction Capabilities of Headliners | This paper discusses the importance of studying different variabilities (test and product variations) that may affect the noise reduction capabilities of automotive headliners, constructed from different materials. For this purpose, interior noise measurements were made at a position approximating the operator ear level, with different headliner materials under various operating conditions. For better understanding of the effect of different variabilities on acoustical performance, various single number values were computed from the measured data reduced in 1/3 octave band frequencies. Statistical data analyses show that the acoustical performance evaluation of headliners is affected by the product variation from one headliner to another, as well as experimental variation due to vehicle performance and test variation. |
A Mathematical Model for Calculating the Dent Initiation Loads at the Door Centers | A computational procedure is presented to evaluate the static dent resistance at the center of a steel door panel. Using the design parameters of geometric shape, thickness and the stress-strain relations of the steel, the static dent initiation load can be calculated. The method is based on the concept of plastic work which is the non-recoverable energy dissipated in the panel by the applied load. A threshold value of plastic work of 0.02 joule is used to signal the dent initiation. A comparison of the computed and measured dent initiation loads of ten experimental panels shows the maximum deviation is less than 20 newtons. |
Automobile Aerodynamic Noise | As engine, tire, and other automobile noise is reduced and as driving speeds increase, aerodynamic noise sources on ground vehicles are becoming relatively more important. They often dominate at cruise speeds above 60 mph. Aspiration and leak noise are strong sources but generally can be controlled by known methods. Turbulent pressure fluctuations due to separated and vortical flows are also strong sources. Much interior noise is caused by transmission of these external pressure fluctuations through windows and other surfaces. The paper presents the variety of aeroacoustic sources on automobiles and reviews the state of experimental data, of analysis methods, and noise reduction principles. A new correlation method for predicting external fluctuating pressures in separated regions is presented. |
Built-In Speaker Car Sound System | The acoustic characteristics of the sound field inside a vehicle cabin were analyzed. On the basis of the analysis results, a three-way horn speaker system for vehicles was developed, comprising a woofer, a mid-range, and a tweeter. For a woofer, we developed a speaker system utilizing resonation of acoustic tubes, in which the acoustic tubes provide acoustic impedance well matched to the acoustic impedance of a vehicle cabin space. In this paper, to identify the influence of standing waves inside a vehicle cabin, we evaluate the sound field reactivity in terms between sound field reactivity and sound image localization or the frequency characteristics. For a mid-range, we developed a speaker system with its directivity controlled by a sound source with a rectangular shape, thereby realizing a well-diffused sound field even in a restricted narrow cavity providing us with the tendency of an expanding sound image. For comparison with the conventional speaker system, data including the accumulative power characteristics and binaural correlation characteristics of this speaker system are presented in this paper. For a tweeter, we developed a system which combines a directivity controlled multi-horn speaker and a digital filter, thus realizing an improved asymmetric sound field and definite sound image localization. For this development, we analyzed the sound field inside a vehicle cabin using the acoustic ray tracing method, and the wave front in the horns by the finite element method. With the above systems, a car audio system has been realized which permits definite sound image localization just in front of a listener, and stereophonic balanced sound reproduction for both the driver's and passenger's seats, for all frequency ranges. |
Combining Materials and Functions for Low Cost Manufacturing of Headliners | Headliners are large parts that must be lightweight, sound absorbent and sturdy enough to carry a complement of other interior components as well. And as the dashboard becomes loaded with more and more technologies, there is a drive to spread some of that complexity over the rest of the interior of the car. Automotive headliners offer an opportunity for slashing vehicle production costs by integrating components and functions in a one-step operation. The headliner is the ideal candidate not only to accept sun visors, lighting systems and hand grips, but also garage door openers, cellular telephones and audio speakers. This paper will discuss the use of low pressure injection molding as a way to reduce headliner production costs while expanding functionality. It will also examine the equipment requirements and the implications of this process for designers and manufacturers of vehicle headliners. |
Agricultural Cab Operator Comfort | Modern agricultural machines are very complex, requiring extensive monitoring of multiple operations at the same time as they travel over very rough terrain. Hence, the cabs must be designed to provide not only good visibility of all monitors and easy access to all controls, but operator comfort and safety as well. This includes climate control (temperature, humidity, dust, noise, etc.), vibration damping, easy access on to and off of the tractor, good visibility from the cab and no controls jutting out where they could constitute a hazard. Good cab design promotes efficiency, comfort and safety. |
Gantry 5 Axis DNC/CNC High Speed Milling and Drilling Machine with Integrated Multiflexible Universal Holding Fixture for the Aerospace Industry | An airplane fuselage structure basically consists of many individual fuselage panels which differ considerably in size and shape. Each individual panel is automatically assembled from individual components, such as the panels, frames, stringers, clips, shear ties, window frames, etc. |
The Modern Chassis Dynamometer as a Testing Device in the Acoustic Laboratory | Development work for the reduction of vehicle noise Is mostly performed in laboratories. The paper describes testing equipment of the latest state of the art that is used in a laboratory for vehicle acoustics. The test specimen and testing equipment are installed in an acoustic chamber. All design measures for noise reduction will be described. The equipment for noise measurement and analysis is included in the chassis dynamometer control and automation system. Noises and vibrations are picked up by special measuring devices and analysed in a separate computer, which is linked to the test stand computer. The results of measurement will be presented and explained. |
Recycling Polyurethanes - An Industry Update from the Polyurethanes Recycle and Recovery Counsel (PURRC) | The Polyurethanes Recycle and Recovery Council (PURRC), a unit of the Polyurethane Division of the Society of the Plastics Industry, Inc., continues to evaluate the technical and commercial viability of current and evolving technologies to recover and recycle polyurethanes. This report will update key PURRC projects targeting automotive polyurethane recovery and recycling issues. Candidate part applications will be reviewed. A project was completed in 1994 to collect post consumer seats from salvage yards and to recover the flexible foam. Process economics and seat collection viability were evaluated. Acoustical foams derived from rigid, semi-flexible and flexible foam scrap combinations are being evaluated. Flexible Slabstock foam production using up to 18% seating scrap has been demonstrated. PURRC is currently recovering polyurethane foam from instrument panels and evaluating techniques to process this scrap into acoustical padding, rebond carpet underlay and industrial structural parts. A study is underway to evaluate the most effective methods to grind flexible polyurethane scrap into powder to be used in the production of seating and headrests. |
Key Considerations when Engineering a Ten Year Instrument Panel | This paper outlines field performance shortcomings historically observed in automotive instrument panels (I/Ps) and discusses the role materials play in these deficiencies. Additionally, specific material development requirements for a ten year instrument panel are discussed. While design and the placement of adjacent vehicle components, such as windshield glass, play key roles in affecting the durability of an I/P, functional and cosmetic performance in large part depend on the materials chosen for construction. Tradeoffs in short term performance (processability during manufacture) and long term performance (field weatherability) often exist for the chemical constituents comprising instrument panel assemblies. In order to obtain an optimal combination of properties, specific performance criteria must be identified and prioritized. Well-defined test methods must be clearly documented and correlated with actual field performance in order to have a methodology to evaluate various material choices. Hopefully, this paper will serve as a framework for discussions focusing on instrument panel constructions for extended vehicle life. |
Data and Methods for Estimating the Severity of Minor Impacts | Front, rear, lateral and side-swipe collisions were staged to correlate passenger vehicle damage to motion. Data from the staged collisions are used to develop severity-prediction methods for the four collision types. Human volunteers were present in many of the vehicles tested. Their responses, and the responses of human volunteers to staged impacts in other studies, are discussed in terms of impact severity. For front and rear impacts, data are presented that correlate the post-impact condition of bumper systems to impact severity. These data build on data previously presented1,2,3. A method for computing velocity change (ΔV) for vehicle to vehicle collisions from vehicle to barrier data is presented. Data from staged low-speed lateral collisions correlate target and bullet vehicle damage to linear and angular velocity change (ΔV, Δω), impact location, pavement friction and collision force. It is shown how momentum, energy and restitution principles can be used to predict ΔV and Δω from damage. For staged side-swipe collisions, damage details are correlated to the target vehicle acceleration-time history. The vehicle motion is characterized as a vibration dose. |
A Survey of Automobile Aeroacoustic Activities in Germany | This survey reports on the salient features of the approaches being pursued in Germany by automobile manufacturers, research organizations etc. to control and inhibit the noise emission from automobiles. The results reviewed are those presented by a number of experts from industry, research organization and universities during a Symposium held in February 1994 in Germany. Topics of concern were among others: sources of noise in automobiles, noise emission measurement techniques, aeroacoustic optimisation of car body and air conditioning equipment, design of and operational experience with new aeroacoustic wind tunnels in Germany. |
Silicone Elastomer Reduces Noise, Vibration, and Squeaks in Vehicle Instrument Panels | Felt tape has traditionally been used as a cushion material between thermoplastic instrument panel (IP) components such as bezels, steering column covers, and trim to reduce noise, vibration, and squeaks that normally develop when plastic materials are adjacent to one another. However, felt tape is expensive as a raw material, and its application is labor intensive. While searching for an alternative cushion material, exploration showed that the use of a one-part, room-temperature vulcanizing (RTV) silicone elastomer offered lower raw material and labor costs versus the felt tape. The RTV silicone elastomer also did a superior job of reducing noise, vibration, and squeaks and provided improved fit for a higher level of overall quality. This paper will describe the process of evaluating the silicone elastomer as a desirable alternative and the cost comparisons of both silicone and felt tape materials. The actual process of applying the silicone elastomer as a cushioning material on the IPs of 1995 General Motors C/K light truck and sport utility vehicles will also be described. Background material on the chemistry of silicone RTVs and some of their other applications in the automotive industry will be presented as well. |
Occupant Retention Glazing for Automotive Sidelites | This paper summarizes joint efforts by Monsanto Company and Excel Industries to develop a cost effective integrated system for automotive sidelites to achieve improved occupant retention. A cost/ performance analysis of a proprietary polyurethane RIM attachment system in combination with two candidate laminate structures (Monsanto “experimental plastic”/ tempered bilaminate + annealed glass/polyvinyl butyral/ annealed glass trilaminate) was completed. While both systems yielded high energy containment capabilities, the trilaminate system was rated higher because it showed superior membrane characteristics after impact and significantly lower fabrication costs. It was determined that such a system could be implemented for an incremental cost of < $100 per vehicle. |
Establishment of Countermeasures in Side Impact by Simulations | To check sharply increasing traffic accident casualties, activities have been underway to analyze accidents and develop safety equipment Automobile makers have placed a great emphasis on improving safety in collision. In this situation, a new side impact standard was introduced in FMVSS 214 in October 1990 and will be applied to passenger cars in 1993 model year. The standard requires an additional full scale dynamic test in which an aluminum honeycomb moving deformable barrier (MDB) simulating the front end of a car is crashed at 33.5 mph into the side of a standstill car at an angle of 27 degrees. The Side impact Dummy's (SID) Thoracic Trauma index (TTI(d)), which is the average of the maximum rib acceleration and the maximum lower spine acceleration, is limited to 90 g's for a 2-door passenger car and 85 g's for a 4-door car. The dummy's pelvic maximum acceleration must remain no greater than 130 g's for both types of cars. Because most compact cars have no more than 300mm crash space between the door and the dummy, this new standard is even more stringent than the frontal impact requirements. This is especially so for a 2-door car, of which lateral rigidity is normally lower than that of a comparable 4-door car, and there have in fact been few makes which met the new standard. In order to ensure compliance with the new FMVSS 214. We have reviewed our conventional development method carefully so that necessary countermeasures for 2-door cars can be incorporated into prototypes and thus much time and money can be saved by avoiding unnecessary design reworks and retests. Previously, we used experimental methods to work out safety provisions on vehicles, but such methods could be time-consuming and expensive, and variations in test had to be always taken into account, often causing delay in engineering release for prototypes. Therefore, the method of numerical simulations was chosen to quickly perform a series of operations from factor analysis to verification of countermeasures worked out As a result goals were achieved in a relatively short time. This paper presents the method of numerical simulation. |
Correction of Finite Element Model for Vibration Analysis Using the Identification System | At the early stage of a new automobile or a new motorcycle development, it is important to grasp and improve its vibration characteristics. To satisfy this demand, finite element method has been applied to vibration analysis in recent years. However, a poor finite element model can cause not only insufficient vibration estimation but also additional development period. Conventionally, an inaccurate finite element model is corrected by trial and error technique to correspond with the experimental results. In this study, a finite element model identification system referring to experimental modal parameters has been developed. The system mainly consists of structural analysis, sensitivity analysis, numerical optimization technique, and evaluation of mode shape correlation. All these processes collectively minimize the difference of calculated and experimental natural frequencies. The system has been applied to automobile and motorcycle structures, and is confirmed to be effective in correcting a finite element model. |
Challenges To Meet Heavy Duty Diesel Engine Euro II And US 1998 Emission Regulations | The paper presents results of engine development and research activities demonstrating the potential of technology currently being developed to meet forthcoming emission regulations for heavy-duty diesel engines in Europe and USA. Development strategies demonstrated in the paper concentrate primarily on the reduction of NOx and PM exhaust emissions while maintaining engine fuel economy and durability. Furthermore, decisive aspects of engine competitiveness are considered, such as minimum necessary complexity of the technical solution in order to minimize production costs, and low engine noise characteristics. |
Tools For Sound Quality Analysis In Complex Sound Fields | As worldwide competition for agricultural and construction equipment increases, manufacturers need to distinguish their products in areas such as operator comfort and perceived quality. Advances in digital audio recording and high speed computers have presented the noise and vibration engineer with the possibility of new tools and techniques for analyzing and processing sound. This paper discusses some of the recent developments in sound quality analysis in passenger cars and how they can be applied to similar engineering problems in off-highway vehicles. |
A New Test Cell Computer for Exhaust and Evaporative Emission Testing | For the increased requirements on computer automatization and data evaluation in the field of emission testing, new programming / computer - technologies are required. To fulfill the requirements of the programmer and the user of the software, Windows NT with object oriented programming was found to provide the best possibilities to control such highly automated, complex systems. Under these directions the new Emission Test Cell Computer (short ETCC) was developed with use of the latest software and hardware technology. The Test Cell Computer provides a control system with integrated storing and paperless documentation of all relevant test data as well as protocols with all today's possibilities to create printouts. Also the managing work necessary for multiple tests running in parallel at the same time in different rooms with progress monitoring is included. The ETCC can easily be integrated into network environments and connected e.g. to existing networks. Data evaluation stations for research and development work can operate on the same network. With the integrated client/server-database, all evaluation stations have access to available data even with multiple test cell computers connected in the network. This was realized by using new technologies for the man machine interface, based on the well known Windows operating interface. |
Investigation Into the Noise Associated With Air Bag Deployment: Part I - Measurement Technique and Parameter Study | High-amplitude, short-duration noise is called impulse noise. A large body of literature on impulse noise has been developed primarily by military researchers for multiple exposures such as those caused by weapons firing. Some research into the impulse noise associated with air bag deployments was performed in the late 1960's and early 1970's to ascertain the risk of hearing loss. Several criteria for risk of noise-induced hearing loss were proposed and much was learned about the sources of the noise. Unfortunately, the instrumentation used to measure the noise in many of those studies lacked adequate low frequency response characteristics. Perhaps more importantly, results from experiments with human volunteers do not seem to agree with the proposed criteria. For this study, a new system consisting of commercially available pressure transducers and microphones was assembled and a new software package was developed. This system allows analysis of the pressure-time data using two analysis methods and criteria proposed in the early 1970's. A series of experiments using this system was run over a four year period to investigate the parameters that affect the impulse noise associated with a deploying air bag. Some observations are presented and conclusions drawn from the data. |
Mathematical Simulation of Driver and Restraint Systems in Racing Saloon Car Impacts | MADYMO 3D software was used to model a racing driver with helmet, racing harness and competition seat, and to evaluate injury parameters in a racing saloon car under European Type Approval impact conditions. Parametric changes in the safety systems were evaluated. The systems protected the driver well, although high neck torques were predicted in frontal impact. Loads on the head restraint were substantially higher than the strength required in regulations. In side impact the head passed through the open window. A window net prevented this, but the predicted loads exceeded the strength of a net tested in the laboratory. |
Noise Attenuation for Polyamide Intake Manifold | Noise Attenuation for Polyamide Intake Manifolds Since the stiffness of polyamide is lower than aluminum, special techniques have been developed to increase local and global stiffnesses of polyamide intake manifolds. The increased stiffness results in parts with noise emissions equal to or less than equivalent aluminum intake manifolds with twice the wall thickness. These special techniques enable engineers not only to attenuate noise, but to “tune” the remaining noise emissions for a desirable sound quality. |
The Aero-Acoustic Wind Tunnel of Stuttgart University | The noise emission of cruising vehicles essentially consists of tire/road noise, drivetrain noise (engine with intake and exhaust system, transmission and driving axle) and aerodynamic noise due to the flow around bodywork, chassis, wheels and cooling air flow (fan). Engines and drivetrains have become quieter due to many man-years of engineering attention and tire noise has also been reduced - at least the noise reaching the passenger compartment. Consequently, the aerodynamic noise of ground vehicles has become dominant at driving speeds above 100 kph both in interior and exterior noise. In order to determine the contribution of aerodynamic noise to the overall noise, measurements are carried out more and more in specially equipped automotive wind tunnels. Besides wind tunnels in which aeroacoustic testing was already envisaged in the specification and design phase, existing wind tunnels can be upgraded to acoustic testing by a suitable treatment of the tunnel airpath and the plenum chamber. The existing 22.45 m2 Open-Jet Automotive Wind Tunnel of Stuttgart University - Institute of Internal Combustion Engines and Automotive Engineering (IVK) - built in 1988 was converted into an aeroacoustic wind tunnel in 1993 by a novel silencing concept. In the return duct of this Göttingen-type wind-tunnel two U-bend silencers were installed upstream and downstream of the fan, using membrane absorbers as thin and smooth vertical splitters (for the low frequency range) in conjunction with profiling the turning vanes with coated porous Polyesterfoam (for the middle and high frequency range). An anechoic plenum chamber was achieved with a new type of broadband absorbers, mounted on the plenum walls and ceiling. Due to its very low self-noise level the IVK Aero-Acoustic Wind Tunnel provides a high potential for the acoustic rating of design optimizations in the development of future vehicles. |
New Acoustic Feedback System | The acoustic feedback (AFB) system is to detect the acoustic signals radiated from a loudspeaker with a microphone, and feed them back to the previous stage of the amplifier. However, there were many problems to put it into practical use. A new AFB system has been developed, where the above problems are solved by setting the microphone at the optimum position and adopting a new feedback method. This was achieved by reviewing the loudspeaker performance from a new point of view. Thus, a wide-range feedback and the improvement in the speaker response have been obtained. Also, the problems of oscillation have been solved. |
A Numerical Investigation of Two-Dimensional Cavity Flow | Results are presented for the application of an acoustic/viscous splitting technique to die computation of flowfields within two-dimensional rectangular cavities for moderate Reynolds numbers. This technique has been previously applied to cavity flows but results were studied only in die acoustic far field and limited to low Reynolds numbers. Implementation of a large eddy simulation model has allowed the Reynolds number range to be extended and direct comparison of computations with wind tunnel results for the cavity near field demonstrates that this technique, which is two-dimensional, may be used to study three-dimensional cavities, provided such cavities are fairly large in their transverse direction. In addition, the flowfield calculation is shown to be sensitive to such parameters as boundary layer thickness, filter width used in the large eddy simulation implementation, and incoming velocity profile. |
Road Noise Modelling Using Statistical Energy Analysis Method | A mathematical model was developed to evaluate design options for control of road noise transmission into the interior of a passenger car. Both air-borne and structure-borne road noise over the frequency range of 200-5000 Hz was able to be considered using the Statistical Energy Analysis (SEA) method. Acoustic and vibration measurements conducted on a laboratory rolling road were used to represent the tire noise “source” functions. The SEA model was correlated to in car sound pressure level measurements to within 2-4 db accuracy, and showed that airborne noise dominated structure-borne noise sources above 400 Hz. The effectiveness of different noise control treatments was simulated and in some cases evaluated with tests. |
Acoustic Modeling and Optimization of Induction System Components | Several aspects of the acoustic design optimization of induction systems are considered. The important role of the inlet manifold in the induction system is shown by constructing mathematical models of two levels of sophistication. A plane wave representation of the manifold is adequate when the geometry of the manifold supports only longitudinal acoustic modes. When the geometry supports transverse modes it is necessary to include the acoustic modal structure in the mathematical model comparing three mathematical models. The manifold with a conventional runner arrangement is shown to introduce harmonics of the firing frequency other than the generally assumed multiples of the number of cylinders. A manifold with runners coupled in a common plane is considered as a means of eliminating undesirable harmonics. It is shown by considering the ninth harmonic (order 4.5), that harmonics other than the integer multiples of the number of cylinders are drastically reduced in amplitude. The difficult problem of generating a good source model for the inherently nonlinear aeroacoustic source at the inlet valve is approached by the use of a simple linear model with source strength and source impedance adjusted to match with data over limited frequency ranges. The car body transfer function is shown to be an important element in the design optimization process which is based on the reduction of driver's ear noise, rather than on snorkel noise. The design process is systematized by using a SIMPLEX optimization scheme in conjunction with a plane wave modeling code. The design procedure is shown to depend heavily on access to acoustic data from a prototype vehicle. This data is required to calibrate the noise source, to establish background noise levels which limit the benefits achievable by induction system optimization, and to provide a transfer function for the car body. |
Blower Motor Whining Noise - A Case Study | Vehicle interior sound quality is regarded as a major quality attribute by automobile consumers and manufacturers. Whining noise, due to its steady state and tonal nature, is easily perceived as an annoyance to normal driving comfort. The blower motor in the climate control air-handling system can be a source of whining noise, especially when the motor is located in the passenger compartment. This paper describes a systematic case study carried out to identify the major noise generating mechanisms of a whining noise from the climate control air-handling system. The paper discusses the use of commonly available tools and techniques to resolve typical automotive NVH concerns resulting in improved sound quality. Particular measurement and analysis techniques presented include sound field mapping using acoustic intensity, resonance identification using transfer functions, three-axis spectrum analysis, and some physical modifications to the source and propagation paths. A variety of objective noise and vibration data is presented and explained. The investigation concludes the source of the whining noise as a type of brush noise. The path is identified as structureborne noise transmitted from the brush-commutator interface, through the motor support structure, to the blower assembly casing, where it is radiated from various positions as airborne noise. The recommended solution is to mount the motor so that it is vibration isolated. Data measured on an iso-mount design is presented to confirm this solution. |
Analytical and Empirical Evaluation of the Impact of Solar Control Glazing on the Thermal Environment in Vans | Spectrally selective glazings that reduce the amount of solar energy entering a vehicle have been developed by PPG to enhance overall passenger comfort and help automotive designers and engineers manage the thermal environment in vehicles. That environment is being affected by such factors as the use of larger glass surfaces, smaller engines, fuel economy goals and refrigerant issues. To quantify the effects of a variety of solar control glazings on passenger comfort and thermal environments, PPG has conducted in-vehicle tests in Arizona evaluating the following glazing systems: the SUNGATE® Automotive windshield, which uses a transparent infrared-reflective coating; SOLARGREEN® Glass, a special composition that reduces infrared energy transmittance, and GL-20™ Glass, a deep-tint privacy glass. The evaluations included measurements of passenger compartment air temperatures, material temperatures, air flow, heat flux through non-glass surfaces, passenger comfort and air conditioner performance. Test results show that these glazing systems are effective in reducing maximum temperatures in parked vehicles, improve cooldown performance following static exposure and reduce compressor work loads. This all leads to improved passenger comfort, improved fuel economy and less damage to interior materials. While desert testing will continue to play a role in assessing in-vehicle performance of glazing systems, there is a need to provide such information in real time as auto manufacturers continue to reduce their development cycle. To that end, a predictive analytical model has been developed. The foundation for that approach is a thermal simulation code that has been modified to allow changes in orientation and the capability to use short time step boundary conditions. Initial efforts in this project, both analytically and empirically, have been focused on simulation of the minivan vehicles. The dynamic nature of both the simulation and the empirical drive test required observation of additional temperature, flow and heat flux sensors throughout the vehicle. Comparisons of the simulation models to empirical results confirm that the analytical approach captures the measured performance of new glazing products in vehicles. |
Acoustics and Microgravity Flight | The effects of acoustic levels in manned space vehicles was not thoroughly appreciated until the STS 40 mission, Spacelab Life Sciences 1 (June, 1991). Previous to that mission, waivers were submitted and equipment operated without overwhelming effect on ongoing flight activities. The factors of multiple pieces of noise producing equipment operating simultaneously, operating in the vicinity of crew sleep stations, and operating for this long of a mission (10 days) became relevant in crew tolerance, fatigue, communication, and permanent shifts in hearing thresholds. Because this was a life sciences mission, accurate instrument measurements were obtained of acoustic levels in the middeck, flight deck and spacelab during flight and physiological measurements were obtained from the crew members during all phases of the mission. Due to the STS 40 results, a Spacelab/Payloads Acoustics Working Group (SPAWG) was formed post flight to address acceptable acoustic limits. The charter of this group was to: Identify and assess orbiter, spacelab, subsystems, and experiment hardware with the objective of reducing the overall acoustic levels on the Middeck and within the Spacelab module to acceptable flight levels. Members of the group represented NASA headquarters, field centers, and payload developers. This paper will briefly address the acoustic impact on crew persons during STS 40, the recommendations of the SPAWG, and current means of addressing acoustic issues within life sciences hardware flown on microgravity missions. |
Customer Based Holometric Analysis | This paper describes a test-based process used to identify structural characteristics of a vehicle windshield wiper system that contribute to customer impression of the sound. The method of paired comparisons determined which wiper system sounds customers preferred. Annoyance ratings of sound components then identified contributors to customer preference. Wiper motor noise was identified as the major annoyance factor affecting system sound quality. This information guided a study of the structures responsible for radiated motor noise. Laser based test methods were used to interrogate the structures clearly identifying transmission paths into the surrounding structure. Paths were then modified reducing structure-borne motor sound as measured with acoustic retests. Thus, a logical technique for hardware testing and modification guided by customer perceptions is presented allowing efforts to be focussed on the most critical aspects of vehicle sound quality. |
Objective Analyses of Binaural Recordings | Aurally-adequate sound measurement technology makes use of both present psychoacoustic knowledge, e.g. loudness, roughness, fluctuation, sharpness and so forth, and Artificial Head measurement technology with transmission characteristics comparable to human hearing. By taking into account psychoacoustic evaluation parameters very often good results for judging sound events with regard to sound quality, as compared to subjective impressions, can be achieved. If a sound situation is relatively complex, i.e. if it consists of various single sound sources at different spatial positions, significant level and phase differences between the left and right ear occur which - in comparison with a monaural evaluation - can yield different results. Such effects have been observed for some time already. Speech intelligibility in a noisy environment, e.g., depends on the positions of the sound sources. Furthermore, investigations into noise in workplaces showed that binaural recordings as compared to monaural recordings caused significantly different physiological reactions of the test subjects. Moreover, it became evident that noise annoyance of single sound sources in a complex mixture of sounds does not only depend on absolute parameters such as A-weighted SPL, loudness etc., but also on their localization. In the interior of a car, for instance, the individual engine orders can produce significant amplitude and phase differences between the left and the right ear, due to wave and multipath propagation, influencing the subjective evaluation. There are no objective measurement procedures available at present. In the last decades a lot of scientific basic research was done on binaural signal processing. Due to the complexity of signal processing in human hearing there have been no complete models yet which simulate binaural signal processing in a simple way and thus constitute a basis for the objective determination of sizes, derived from a binaural measurement to describe subjectively perceived sound quality. Therefore, investigations aiming at the selection of certain signal components from a complex mixture of sounds were carried out, based on additional information such as directional sound incidence of the sound sources under test or engine r.p.m. for selecting individual engine orders. On the basis of known models to predict speech intelligibility in a noisy environment, binaural models for the objective determination of sound quality, based on these simple application examples and Artificial Head recordings, were developed. |
Engine Noise Reduction Using Narrowband Feedback Control | A narrowband feedback control is developed to cancel periodic noise. The method consists of digital bandpass filters centered at a reference frequency and its harmonics. Each of these bandpass filters is then followed by a finite impulse response (FIR) filter which changes the phase of the control signal to achieve the 180° phase shift in the open loop system. A gain is applied to the control signal to adjust the overall noise reduction, considering reasonable stability margins in the system. In a set of experiments the proposed technique was compared with the filtered-x adaptive feedforward control method. The periodic noise, introduced by a noise speaker, inside a reverberant box was controlled (reduced) using both techniques. With the gain properly adjusted, the amount of noise reduction at the microphone was slightly less than that achieved by the filtered-x adaptive control, but the stability characteristics of the feedback control system was considerably better. The feedback system was able to maintain a gain margin of about 6 dB's and a phase margin of 45° over the entire frequency range of interest while the feedforward controlled system became unstable at a few frequencies even with very slow adaptation rates. The proposed feedback technique was also used to attenuate the interior noise, due to the firing of the engine, in an automobile. The reduction of up to 8 dB's in sound pressure level at the driver's head was achieved. |
Application of Noise Control and Heat Insulation Materials and Devices in the Automotive Industry | Automotive noise control involves many aspects of the total vehicle design - the powertrain, body structure, chassis and so forth. Noise control materials in conjunction with intelligent vehicle design can help produce a pleasant, desirable vehicle. Understanding the basic functions and uses of noise control materials is one of the objectives of this paper. In some situation, thermal insulation materials are combined with or used in conjunction with noise control materials, and an understanding of the thermal properties of materials can be useful. Vibration isolators are important devices in controlling the transfer of sound and vibration energy and these are discussed. |
Investigation of Different Techniques for Quantifying Automotive Panel Noise Radiation | In the process of determining optimal treatment locations and compositions for automotive noise control parts, it is necessary to know both low frequency and high frequency sound contributions of automotive interior sheet metal panels. Several techniques of experimentally assessing individual panel contributions to coherent, low frequency noise as well as incoherent, high frequency noise are investigated. These include use of a sound intensity probe, a pressure gradient microphone and an accelerometer for measurement of panel vibrations. Acoustical insulation of all interior surfaces except a particular surface of interest (the “windowing” method) and boundary element modeling (for exclusively low frequency characterization) are also investigated. While no one technique is ideally suited to determining contributions in the entire audible frequency range, the boundary element method was found to be particularly useful for coherent source characterization, while the more traditional “windowing” method is well-suited to incoherent source characterization. |
Sound Quality Assessment of Powered Seat Adjusters | With the extensive improvements achieved in vehicle driveline and road noise quality manufacturers are turning their attention to component and ancillary noise sources and expecting their suppliers to include sound quality in the assessment of their designs. This paper describes an investigative project into the principal components contributing to the perceived sound quality of powered seat adjusters in passenger vehicles and the statistical methods of analyzing jury preference data. |
The Ford Motor Company Advanced Engineering Center | The Ford Motor Company Advanced Engineering Center contains 100,000 square feet of sound and vibration laboratories, induding full vehicle chassis dynamometers, powertrain dynamometers, and sound quality evaluation chambers. The facility houses the first U.S. All-Wheel-Drive NVH Chassis Dynamometer (4 independent motor drive), the first U.S. All-Wheel-Drive NVH Powertrain Dynamometer (4 independent motor drive) and other unique elements, such as innovative wedge construction for the acoustic chambers. |
The Chrysler 3/8-Scale Pilot Wind Tunnel | The Chrysler 3/8-scale model automotive wind tunnel is a pilot facility for a planned full-size tunnel of the same design. The 3/8-scale tunnel, which has a complete compliment of instrumentation including a pressure system and high-precision balance, will also be used for 3/8 model aerodynamic development testing of vehicles after piloting is complete. The tunnel is convertible from a slotted-wall test section to a semi-open jet test section. Commissioning, calibration, and piloting results show the performance of some features being piloted including slotted-wall effectiveness, open jet collector performance, and tunnel background noise levels. Calibration results include static and dynamic pressure distributions. |
On the Induced Noise of Test Sections in Different Wind Tunnels and in the Cabin of a Passenger Car | An acoustic comparison test of eleven European and two American full-scale automotive wind tunnels was carried out with a passenger car. The scope of investigation comprised in-flow and out-of-flow background noise measurements of the empty test sections as well as interior noise measurements inside the passenger compartment of a standard type Volkswagen Passat Variant CL. For this purpose seven different vehicle configurations were investigated in the various wind tunnels. The aim of this experimental investigation was to establish physical criteria in order to carry out a suitable acoustic comparison between wind tunnels with different types of test sections and to establish upper limits of wind tunnel background noise levels where acoustic measurements inside a passenger compartment are questionable. |
Measurement and Analysis of Gaseous Exhaust Emissions from Recreational and Small Commercial Marine Craft | In general, propulsion systems used in recreational and small commercial marine craft exhibit some unique design and installation characteristics, which demand special attention from the standpoint of emissions measurement and data interpretation. For example, the exhaust system is often a compact folded design which terminates partially or completely underwater. Also, water is normally present throughout much of the exhaust ducting in order to provide cooling, noise reduction, and tailored exhaust tuning characteristics. Marine industry efforts have led to the development of a measurement standard (ICOMIA 34-88) which is being used to evaluate marine propulsion systems in anticipation of future exhaust emission regulations. This paper discusses the rationale used to develop the measurement and data analysis procedures, and presents the complete ICOMIA standard as an appendix. |
Standardization of a Test Track Surface for Use During Vehicle Noise Testing | A group within the International Organization for Standardization has worked out a standard for a road surface intended to be used during vehicle noise measurements according to the ISO 362 and 7188 procedures. The surface should be equally suited for use in similar measuring procedures where full-throttle operation of vehicles is needed and where the influence of the surface on noise emission and propagation must be kept at a minimum. Several test tracks have been laid according to the proposed specifications. A Round Robin Test has been conducted in which five cars and one truck were run on a number of test tracks in Europe and Japan. The results show that the surface meets the basic requirements of giving low tire/road noise while still having negligible sound absorption characteristics. Also, the site-to-site variability is low. In this paper, the convener of the working group presents the work and a preliminary proposal. The final proposal is scheduled to be presented in the summer of 1991. |
Active Control of Simulated Road Noise | Active noise control is a potential method for controlling troublesome low frequency road noise in the passenger cabin of automobiles. In this investigation, the control of simulated road noise in a four door automobile is studied. Active control of road noise requires that the inputs to the controller sense a significant part of the energy causing the noise. Only the coherent energy between the input sensors and the performance microphone is controllable. An investigation is conducted of the control achievable using accelerometers mounted at various positions near the rear wheel of the vehicle as inputs to the controller. The best input sensor location was used with a commercial active noise controller to reduce simulated road noise near the driver's head location. The measured reduction is compared with the results predicted using the coherence. Additional controller simulations were developed to predict and better understand the performance of various controller types in this automobile. |
Acoustic Analysis of Truck Cab | This paper presents the results of acoustic analyses of light duty truck cabs by actual vehicle testing and by numerical analysis utilizing the boundary element method (BEM). In the resonance mode analysis using BEM, by taking into account the vibration characteristics of cab panels, the presence of the modes other than the purely acoustic cavity resonance modes were confirmed. The contribution of the panel vibrations to booming noise that occurs in actual light duty trucks was analyzed. BEM analysis showed that some of the panel vibration had a negative contribution to booming noise. In other words, decreasing vibration in such a section was shown to increase sound pressure. The results of the BEM analysis match well with actual test results. It has thus been demonstrated that BEM is an effective method for analyzing truck interior noise reduction. |
Integrated Flight-Propulsion Control Concepts for Supersonic Transport Airplanes | Integration of propulsion and flight-control systems will provide significant performance improvements for supersonic transport airplanes. Increased engine thrust and reduced fuel consumption can be obtained by controlling engine stall margin as a function of flight and engine operating conditions. Improved inlet pressure recovery and decreased inlet drag can result from inlet control system integration. Using propulsion system forces and moments to augment the flight-control system and airplane stability can reduce the flight-control surface and tail size, weight, and drag. Special control modes may also be desirable for minimizing community noise and for emergency procedures. The overall impact of integrated controls on the takeoff gross weight for a generic high speed civil transport is presented. |
Development and Application of Simulation for Low-Frequency Boom Noise and Ride Comfort | This paper investigates a new approach to the quantification technique for road induced vehicle interior noise and vibration within the frequency range up to 40 Hz. By employing the least squares method, both vertical and fore-aft load to each wheel were quantified using transfer function and actual vibration response of the vehicle driven on a road. The coupled structural-acoustic vehicle model using the finite element method, which is also detailed in this paper, is combined with the quantified input load to simulate road induced interior noise and vibration response. Experimental verification, which indicates reasonable accuracy of the simulation, and an application for the prototype development are also presented. |
Development of Composite Materials Applications to Production Nacelle Component Structures | The main engineering problems requiring solution in a development programme aimed at the application of composite materials to selected nacelle components are reviewed. The components chosen were characterised by important special features including acoustic performance, fireproof capability and resistance to fan-blade off effects. The subsequent application of the developed technology to meet production nacelle requirements and Airworthiness compliance needs is discussed. |
Corrosion Protection of Galvanized Steel Sheet-Corrosion Investigation of Field Vehicle | Three doors from three field vehicles made with one-side galvanized steel on the inside of the outer panels were investigated for perforation corrosion using microscopic and analytical methods after 8 or 10 years' field exposure in the snow-belt areas of North America. Perforation of these doors occurred within the lapped part of the door hems. Outer panel perforation began at the zinc layer on the inside surface of the outer panel at the lapped part and/or at the “bent part” of the outer panel of the door hems. Details of the micro corrosion behavior for the inside surface of the outer panel were made clear using EPMA analyses. The corrosion products on the inside surface of the outer panel were identified with X-ray diffraction. Initially, zinc corrosion begins at the zinc coating layer of the upper side at the wax-free zone of the lapped part. Eventually zinc corrosion occurred beneath the wax layer as “Under-film corrosion”, proceeding gradually from the bottom to the top of the lapped part. The zinc is transformed into ZnO from the protective ZnCl2·4Zn(OH)2 initial product. Eventually, the steel substrate corrodes after the zinc coating loses its sacrificial corrosion protection. The steel is transformed into Fe3O4 and α, γ-FeOOH. It was found that this corrosion behavior was a common phenomena for the observed door hems. |
Rollover Crash and Laboratory Tests of Ejection Reduction By Glass-Plastic Side Windows and Windshields | About one fourth of the occupant deaths in passenger cars in the United States involve either complete or partial ejection. Approximately one half of these ejections are through glazing areas. This paper presents research results which demonstrate the potential of glass-plastic glazing to significantly reduce ejections through motor vehicle windows. Four passenger car and four light truck and van rollover experimental crashes were conducted. All the vehicles had glass-plastic front side window glazing. One of these included the improved glazing with a movable encapsulated “offset T-edge” design. Two in addition had glass-plastic windshields. Even with glass breakage and window frame distortion, the glass-plastic glazings maintained their “safety net” ejection reduction function. Laboratory dummy drop and sled tests of the movable glass-plastic glazing side windows are reported. Component tests are discussed which use 10 pound and 40 pound, eight inch diameter, chamois - covered spheres as test devices to evaluate the characteristics of the improved glazing relative to the Head Injury Criterion, laceration, and ejection reduction. Research remains to be carried out to assure sufficient deformation of the safety net glazing system to provide acceptable neck loads under severe glazing contact conditions. |
Carbon Epoxy Perforated Skin for Nacelle Acoustic Treatment | The acoustic treatment requirement for jet engine nacelle inner flowpath leads to using perforated skin. Formerly in light alloy these skins are now composite and new techniques have been developped to achieve the perforation. After reviewing different possible techniques (mandrel tool, abrasion, stamping, mechanical drilling,…) one process is chosen and described in terms of skin mechanical properties, cost, and production facilities. |
Parameter Identification for Noise Prediction in Car Structures | The investigation of the static behaviour of structures, especially car bodies, by analytical methods is a very important and widely used tool in the automotive industry. It is much more difficult to predict noise phenomena. The key point is that many physical quantities determine the sound in the car (1)*. The relevant physical effects must be identified in order to get a reliable mathematical model. The paper describes how this can be done by a combination of experimental and analytical works. The frequency range of interest is up to 200 Hz |
Using Fiber Optics and Laser Fluorescence for Measuring Thin Oil Films with Application to Engines | A new method has been developed for measuring the oil films on cylinder walls in engines that offers benefits in improved understanding of oil transport and consumption. The unique aspect of this work is that fiber optics and laser induced fluorescence are combined to measure the oil film thickness. As a result the system is much less intrusive than previous methods using windows to observe the fluorescence. Static tests were used to demonstrate the characteristics of the technique. Dynamic tests, performed on a Cameron Plint wear tester, showed the capability of the system to measure thin films under dynamic conditions and at high loads and temperatures. Finally, the system was installed in a diesel engine and used to measure oil film thicknesses under fired conditions. |
Side Impact Crashworthiness Design: Evaluation of Padding Characteristics Through Mathematical Simulations | The National Highway Traffic Safety Administration (NHTSA) has developed a lumped mass computer model which simulates the interaction of a struck car door and an adjacent two dimensional seated dummy in side impacts. This model was used to investigate the effect of various vehicle design parameters on occupant responses and to define various methods to improve vehicle safety performance. This paper discusses the effectiveness of door padding and side structural stiffness to minimize potential for occupant thoracic injuries in 90° side impacts. Occupant response data were obtained with the aid of the computer model for a Moving Deformable Barrier striking a car at lateral velocities of 25, 30 and 35 mph. To determine the optimal padding and structure needed to minimize potential occupant injury, the Thoracic Trauma Index (TTI) was mapped in terms of different levels of struck car side stiffness and padding characteristics. |
About the Threshold for Fatal or Potentially Fatal Injuries in Car-to-Car Side Collisions - A Comparison Between Real Accidents and PMHS-Tests | This analysis is part of a retrospective real accident study of 670 occupants in 428 cars. In most cases the real accidents were reconstructed from police reports by means of photographs, accident drawings and descriptions of the damaged cars. In fatal crashes the cars, and in most cases the sites of the accidents were examined. Among 272 occupants involved in car side collisions, we found 41 belt protected near side front passengers, whose cars were impacted by another car with main impact points at the front passengers' doors and B-pillars. The analysis of the correlation between technical parameters of the real accidents and injuries of the passengers showed a high significant discrimination between MAIS and some regional AIS 0-3 on one hand, and MAIS and some regional AIS 4-6 on the other hand already for each of the technical variables EES, delta v and maximum deformation. The comparison between these 41 real accident cases and 57 PMHS (postmortem human subjects) tests (15)* proved a significant difference between the thresholds for fatal injuries in respect to maximum deformation. The mean values of maximum deformation for fatal injuries in the real accidents were significantly higher than in the PMHS-tests. The possible causes of the differences are discussed. |
Cold Start Improvements With a Heat Store | The Heat Battery, a latent heat store, accumulates waste heat of the engine and preserves it by efficient heat insulation. On the next cold start, after a day or a weekend, the heat is released with an initial power of 50 to 100 kW. This energizes the vehicle heating system within seconds, allowing for hot air to flow instantly to the cabin and to the windshield. The passenger comfort is immediately felt, and the windshield can be defrosted or demisted without manual help. Due to the high heating power the engine will warm up within 30 seconds so that the tailpipe emissions of carbon monoxide are reduced up to 50% and unburnt hydrocarbons up to 30% in the first bag of the CVS-Test. |
Overview of a Study on Direction-of-Motion Stereotype Strengths for Automobile Controls | Virginia Polytechnic Institute and State University recently conducted an SAE sponsored research study investigating directional stereotypes of six types of automobile controls: power mirrors, power windows, manual windows, stalks, generic controls, and power door locks. The objective was to determine stereotype strength and the reasons for the strengths. Two hundred subjects participated in this study. This paper provides an overview of the results of the study and recommendations made therefrom. |
A Plan to Prevent ESD Damage on Electronic Components at an Auto Radio Process Assembly | Everybody has already had the ungrateful experience of walking on a carpet tile and receiving an electric shock just by touching a door knob. What many people don't know is that, simply the fact of walking a few meters over the carpet can generate some kilovolts of electrical charge and cause a damage of some thousand dollars on electronic devices such as computers, radios, electronic controls, etc, due to the fact that they have components sensitive to a few hundred volts or less. The most common way of generating Electrical Static Charge is frictioning two different materials against each other. Electrons are transfered from one surface to the other making one more positive then the other this imbalance can easily reach the order of some hundred volts. Today, the automotive industry uses a large quantity of a wide range of electronic components in its products (cars, trucks, etc.) not only for entertainment, but also on the drive control area, (engine, powertrain control etc.). Where no failure can be admitted because driveability and safety can not be jeopardized. So, it is very easy to undestand why an Electronic Assembly Plant that uses millions of sensitive devices every year needs a well defined plan to prevent the effects of Electrostatic Discharge. |
Use of One ST9 Timer for Handling a J1850 50 Kbit/Sec. Implementation | This paper describes a mixed hardware and software implementation for the SAE-J1850 protocol (1). This implementation is general and can be adapted to most J1850 based systems. Each node is entirely managed by one ST9 microprocessor. That means that the same micro controls the application and the bus. To interface with the bus the micro uses one ST9 16-bit timer and two register banks. As a result this system can be implemented using any ST9 microprocessor. Only a simple external circuitry is needed to drive and buffer the bus, as well as filtering the incoming signals. Bit decoding, CRC check/generation and consistency checks are done internally to the micro, thanks to the sophisticated hardware of the standard ST9 16-bit timer. The data link, network, transport, session and presentation layers are implemented by software. Therefore this implementation is perfectly suited for nodes with application layers of medium complexity, such as doors, lights, speed control, A/C control, instrumentation, distributed audio modules, etc. |
Temperature Measurements During Flash Welding Thin-Walled Door-Frame Components | This study was conducted to examine the effect of flashing conditions on the resulting temperature profile during flash welding automobile door frames. Previous work on temperature profiles of flash welds has shown that at some point in the welding cycle a steady state temperature is reached, minimizing the need for further flashing. The indication of such a minimum flashing time allows flashing conditions for any application to be optimized. Unfortunately, previous work has been limited to rather heavy section materials, and the results could not be directly applied to the flash welding thin sections typical for door frames. This program was a preliminary study to examine the effects of initial flashing velocity and flashing acceleration on the resulting temperature profiles in U-shaped channel sections. Work was done on a cam driven flash welding machine supplied. Flashing conditions were varied by using cams with different profiles. The first cam was a linear cam typical of that used for production of this part. In addition, three new cams were prepared. These included a cam with a linear flashing profile using twice the initial flashing velocity of the production cam, and two cams with parabolic flashing profiles. Both parabolic cams profiles used half the initial flashing velocity of the original cam. All cams used roughly the same flashing time, resulting in different degrees of burn-off. Temperature measurements were made by locating thermocouples at increasing distances from the original interface. During welding, temperature was recorded from these thermocouples as temperature versus time data. For each set of flashing conditions, separate experiments were run to characterize temperature profiles on the three sides of the channel section. Resulting temperature versus time data was then transformed to temperature versus distance from the flashing interface data. This data was curve fit to an exponential expression, and the results of that curve fit used to calculate effective forge depth of the workpiece. The results of this program show that the parabolic cams reach steady state temperature faster than the linear cam, and are consistent with the published literature on heavier section flash welding. However, it was also noted that excessive flashing velocities (as a result of either a high initial flashing velocity or too high a flashing acceleration) tended to overheat the part. Higher flashing velocities result increase the rate of heat generation during flash welding. It is believed that the relatively long stick-out lengths used in this application, and the relatively poor conductivity of the dies prevented heat from being extracted at a sufficient rate to maintain a stable temperature profile. Apparently, heat generation needs to be balanced between that necessary to achieve stable temperature conditions in a reasonable time, while not overheating the workpiece. |
Advances in Thermoset Injection Molding | Injection molding of thermosetting materials such as low profile SMC/BMC composites found increasing application in the transportation industry in the eighties. Such automotive parts as front end panels and rear/hatchback doors have grown in usage. The rear doors have reached exceptional production levels of 2500/day in a single plant. The injection process offers the advantages of greater automation for the mass production of body panel parts compared to compression molding. However, the injection molding of fiber reinforced low profile composites suffers from a severe reduction in physical properties. This is particularly true for impact strength which can be one-third that of similar compression molding materials. A primary reason for this is due to the degradation of the reinforcement during the processing/molding. Efforts at increasing the physical properties through processing changes have many times caused problems with the surface smoothness of the moldings. Should major improvements in impact strength be coupled with excellent surface appearance the injection process could be applicable to automotive hoods, doors, deck lids, etc. The resultant application of automation could provide a more favorable cost structure for these composites versus metal even at high volumes of production. This paper reports on a concerted study of this problem involving examination of the organic matrix system, shrinkage control materials, interfacial agents, glass sizing changes, chemical thickening and various processing parameters and injection molding machines. This work has resulted in truly super Class A surface molding at impact strengths 80% above those of the best standard injection materials. Progress of this nature signals the beginning of a new day in low profile thermoset injection molding. |
Gas Injection Molding of Thermoplastic Composite Window Guidance Channel | Gas injection molding of reinforced engineering plastics for structural applications is a very innovative approach, but is still in an infancy stage. The requirements for window guidance channel are: dimensional stability, high strength to weight ratio, no warpage and low wear. The composite materials with hollow tubular structure can only meet these requirements based on FEA analysis. We evaluated 30% glass filled polyester (short and long glass fibers). The part and tool designs are the key parameters for successful results which are discussed. Information on current gas injection molding technologies is discussed. The new software ‘C-Gas flow analysis’ was used to optimize gate design and process parameters. The design of experiments based on Taguchi method was used. Both available technologies, i.e., gas through nozzle and gas through runner or cavity were tested. The cross section analysis was done using CAT Scan. This is the first structural application of gas injection technology which is fully tested and approved according to GM specifications. We received Society of Plastic Industries (SPI) ‘Award of Excellence’ for design and application development in February 1990. |
Aerodynamic Noise of Ground Vehicles | As engine, tire, and other automobile noise is reduced and as driving speeds increase, aerodynamic noise sources on ground vehicles are becoming relatively more important. They often dominate at cruise speeds of 65 mph. Aspiration and leak noise are strong sources but generally can be controlled by known methods. Turbulent pressure fluctuations due to separated and vortical flows are also strong sources. Much interior noise is caused by transmission of these external pressure fluctuations through windows and other surfaces. The paper presents the variety of aeroacoustic sources on automobiles and reviews the state of experimental data, of analysis methods, and noise reduction principles. A new correlation method for predicting external fluctuating pressures in separated regions is presented. |
Climate Measurements for Glass with Different Energy Properties | Recent developments in glass treatment techniques have made it possible to improve vehicle compartment climate considerably. At the same time, it has become obvious that traditional temperature measurements do not cover the total need for describing climate properties. This is due to the fact that human heat balance, which is the fundamental process behind feeling cold or hot, is a function not only of temperature but also of draft and radiation. Coating glass is one means of preventing solar radiation from coming into the compartment. In doing so, the solar heat load through the glazing can be reduced by some 50 %. This, of course, gives a lower compartment temperature in parking conditions and also a faster cool-down in hot climate. It has two major secondary impacts on the human being: At a given air flow through the compartment, the necessary inlet temperature is increased, thereby causing less draft. Direct radiation on body surfaces is also reduced. The total evaluation of glass with reflecting or absorbing properties must therefore include measurements with instruments like the Bruel & Kjaer comfort meter or the Voltman system as presented in SAE reports nos. 850042 and 890049. The latter system, which gives a total picture of heat load on different body parts in a given situation, is of course the most sophisticated method for this part of the evaluation. In this paper, some suggestions are given for testing routines. They include: parking heat-up and idling cool-down tests. Voltman on-road testing and simulated on-road testing outdoors. |
Development of a Test Procedure for Quantifying Performance Benefits of Solar Control Glazings on Occupant Comfort | The evaluation of the performance benefits of solar load reducing glazings using production vehicles is key to the establishment of the product cost/benefit ratio. Climatic windtunnels normally used to evaluate heat gain and vehicle cooldown can not provide true solar simulation. Comparative testing using a test car and a control vehicle must therefore be conducted outside in uncontrollable ambient conditions. The subject paper deals with the development of a testing methodology capable of quantifying thermal performance differences, as low as 5%, resulting from component differences, including glazings. The procedure described includes the use of B & K Thermal Comfort Meters to standardize the refrigeration system performance and to evaluate the rate of vehicle interior cooldown. Data taken during summer test programs in the Southwest for evaluation of heat absorbing glazings will be reviewed. Data to be presented include interior air and surface temperatures during soak testing and cooldown comparisons under city drive conditions. The general relationship of comfort meter data to driver comfort index will also be discussed. |
Solar Control Glass with Neutral Color for Automobiles | This paper describes monolithic solar control glass with high durability and neutral color (colorless reflection) for automotive windows. Layer systems of the solar control coating are composed of double layers (oxide/nitride/glass) and triple layers (oxide/nitride/oxide/glass), where a titanium nitride film is chosen for solar energy reduction and a novel zirconium based oxide film with a low refractive index is used as a protective layer together with reducing optical interference color. The nitride film and the oxide film are prepared by reactive dc magnetron sputtering from a titanium target and an alloy target without intentional substrate heating, respectively. Durability of the double layer coating is investigated against abrasion, chemicals and weathering. When the coating is applied to all windows of a passenger car, the reduction of a solar heat load is evaluated through an air-conditioner at simulated car speed under simulated solar radiation. |
Non-Destructive Replication Technique for the Examination of Phosphate Crystal Morphology on Vehicle Assembly Lines | Destructive or indirect methods have been available for evaluating phosphate crystal morphology on car bodies pretreated on a vehicle production line. Either the panel in question is removed, thereby destroying the car, or flat panels are hung in the window openings with the assumption that the same morphology exists over similar substrate surfaces on the stamped autobody. The replication technique described in this report has proven to be a viable option for examining the phosphate crystal morphologies present on various automobile substrates. The details of this replication technique along with crystal morphologies associated with different substrates and degrees of forming are included in this report. |
Air Conditioning Electric Vehicles with an Electronically Driven Variable Speed Scroll Type Compressor | A realistic air conditioning system for electric vehicles, (EV), which minimizes the sacrifice of drive range is proposed in this paper. A variable speed semi-hermetic scroll compressor and an automatic louver outlet air temperature control method for a small delivery van are used to attain suitable cooling performance and interior temperature controllability with acceptable noise characteristics. This air conditioning system, (A/C), offers a pre-cooling feature simply by tapping power from commercial electricity outlets before departing for service. The effect of a practical heat influx reduction applied to the vehicle, and of condenser improvement, is evaluated in terms of the electric power consumption and the actual sacrifice of the vehicle's drive range. |
On-Line Paintable Polypropylene Compounds for Automobile Body Panels | The use of plastics to make the bumpers, doors, fenders and other exterior body panels has increased greatly in recent years. Efforts have been made to achieve on-line paintability so that plastic and steel body parts can be painted at the same time. This has already been accomplished for polyamides and certain polymer alloys such as polyphenylene ether/polyamide. In the field of general-purpose plastics such as polypropylene, recent advances in composite material technology have made it possible to develop general-purpose plastics that display properties comparable to those of engineering plastics. We have succeded in developing new polypropylene compounds which combine excellent thermal properties, high impact strength, and low coefficient of linear expansion. In addition, they can be painted on-line in lamp finisher and front bumper applications. |
Development of Rubber Contacts Used for Power Window Switches | We have developed a power window switch unit for use in multiplex wiring systems for automobile doors. As the systems are multiplexed, signal switches mounted on PC boards prove to be more advantageous than conventional switches having a metal spring and metal contact. We chose to use a rubber contact in one of the signal switches, and combined a good operational feeling into the rubber contact, thereby succeeding in designing a switch structure that requires less parts. We expressed the operational feeling of the switch by four values, and designed the switch with the help of CAE to meet each of the values. We could therefore develop a rubber contact with an operational feeling as high as we had aimed without the need to make any prototypes. |
On Determining the Relationship Between Vehicle Value and Interior Noise | A PC based survey tool has been used to measure the value of a luxury vehicle as a function of its interior noise level at 70 mph. Two straight lines were required to fit the change in value (measured in dollars) with noise level depending upon whether noise was greater or less than a baseline level of 66 dB(A). The slopes of the lines differed by a factor of two with the value loss curve asociated with a noise increase from the baseline level being the steeper of the two. A difference in the value relationships between gains and losses in this manner is expected from prospect theory. When the noise level in dB(A) was adjusted to represent a sones-like scale using a conversion based upon a broadband noise spectrum, the measurements followed a single straight line reinforcing the view that the sones scale is more nearly a “pure” psychometric scale than dB(A). The results also suggest that, when persons are asked for their willingness to pay, their response threshold for losses is much more sensitive than their threshold for gains. The findings are discussed in terms of their implications on designing automobiles for competitive markets. |
Safety Testing and Evaluation of Polycarbonate Vehicle Glazing Using Full Scale Crash Testing Procedures | This paper presents the results of a comprehensive research program addressing the safety issues pertaining to using Polycarbonate glazing for non-windshield vehicle glazing. A series of crash test procedures were used to evaluate the Polycarbonate glazing alternative. The test procedures utilized included High Speed Lateral Impact (HSLI), Narrow Object Intrusion or Pole Impact, Dynamic Rollover, and Inverted Vehicle Drop tests. It should be noted that component-level dynamic impact testing of a variety of Polycarbonate designs was previously conducted as part of this ongoing research program [1]. This testing included 40 lb guided headform and Free Motion Headform (FMH) testing. In regard to vehicle glazing, there are a number of important occupant safety issues. These include occupant containment, injury due to occupant impact with glazing, and laceration. Throughout the project, emphasis was placed on the careful monitoring of the test results with regard to these three issues. The intent of this study was not to specifically highlight the safety benefits of Polycarbonate glazing, but more to fully investigate the Polycarbonate glazing alternatives to determine whether there are increased safety risks accompanying a switch to this type of glazing. The vehicles that were used for this project are quite popular to the North American market. These vehicles included a 1997 Ford Taurus, a 1997 Chevrolet Cavalier, and a 1997 Dodge Grand Caravan. For each Polycarbonate test, the vehicle's non-windshield Tempered Glass glazing was replaced with 4 mm Polycarbonate glazing. The Polycarbonate glazing was bonded into the vehicle using an automotive adhesive common to the industry. Although this approach is not feasible for moveable window applications, one of the reasons it was chosen was to produce the highest possible loads on the Polycarbonate window. Throughout this study, it became increasingly clear that there are many safety issues to consider with both Polycarbonate and Tempered Glass. From an injury standpoint, the three most common areas associated with glazing are laceration potential, impact injuries, and ejection. This project focused on these three areas. For the most part, the evaluation of the glazing performance with respect to these areas is direct and the techniques used for assessing these injuries is accepted by the safety industry. The difficulties arise when considering the relationship between impact injury and ejection. When considering overall safety, if there is glazing breakage, then there is higher potential for occupant ejection. Conversely, if there is not glazing breakage, then the potential for occupant ejection is eliminated (at least through the glazing), yet the injury potential due to glazing impact is increases. The issue arises as to how the injury due to the glazing impact compares to the injury potential when there is a partial or full ejection. Whenever there is an ejection of any kind, the range of objects that an occupant can strike is quite substantial and difficult to measure in laboratory testing. Therefore, one must carefully evaluate all potential and/or avoided injuries when considering the overall safety provided by one particular form of glazing compared to another. In order to set the stage for the rest of the paper, it is important to briefly define a few terms as they are used here. A “Primary” impact is defined here as when there is direct glazing contact between the occupant and glazing.“Secondary” impact is defined as any occupant impact that is only possible when there is glazing breakage. The testing results revealed a number of significant trends. Based on the tests conducted in this study, the Polycarbonate glazing did not result in any major fractures due to the initial impact event in any of the test cases. Secondly, based on the testing, it has been shown that the impact injury potential of the Polycarbonate glazing appears to be no greater than other interior components of the vehicle. This is based upon film and data analysis in which contact between the occupant and glazing and other surfaces was studied. Overall, the results of this testing indicate that there does not appear to be an added safety risk with Polycarbonate glazing when all the facets of occupant injury potential are considered, and, in addition, there may be a significant safety benefit in the form of occupant ejection containment. |
Locking Actuators Today and Beyond | Hydraulic actuators with internal mechanical locks are attractive when safe repeatable positioning is required along with insensitivity to load and hydraulic pressure variations. Internal locking designs generally offer a lighter, smaller, better protected solution than external locks for applications such as: landing gear, doors, highlift devices, inlet/exhaust geometry control, and armament positioning. The evolution of higher pressure hydraulic systems imposes design challenges because of smaller areas, higher stresses, and high release loads. This paper looks at the experience of one supplier of locking actuators, Dowty Decoto, Inc. (DDI), and at the technology that is, and will be, required to provide the industry with functional, reliable locking actuators. |
A Consideration Of Wind Noise Reduction By Air Flow Control | The relation between the wind noise level at high speed cruising and the vehicle body shape was studied. The wind noise level in the vehicle depends on the external aerodynamic noise and the noise isolation characteristic of the weatherstrip, body panel and so on. In order to reduce the wind noise level; the modification of the body shape is an important Batter. Based on model experiments, it is shown that the aerodynamic noise is generated mainly on the front door windshield glass and its level is effected by the air flow around front pillar. As the aerodynamic noise is induced by the velocity or pressure fluctuation of air flow, the relationships among the front body shape, the air flow fluctuation and the aerodynamic noise are described analytically. The results were applied to the improvement of design of the production vehicles. |
Evaluation of Composite Components on the Bell 206L and Sikorsky S-76 Helicopter | Progress on two programs to evaluate structural composite components in flight service on Bell 206L and Sikorsky S-76 commercial helicopters is described. Forty ship sets of composite components that include the litter door, baggage door, forward fairing, and vertical fin have been installed on Bell Model 206L helicopters that are operating in widely different climates. Component installation started in 1981 and selected components are being removed and tested at prescribed intervals over a 10-year evaluation. Four horizontal stabilizers and ten tail rotor spars that are production components on the S-76 helicopter are being tested after prescribed periods of service to determine the effects of the operating environment on their performance. Concurrent with the flight evaluation, materials used to fabricate the components are being exposed in ground racks and tested at specified intervals to determine the effects of outdoor environments. In this paper, results achieved from 73,000 hours of accumulated service on the 206L components and 50,000 hours on the S-76 components are reported. Six ship sets of 206L components have been removed and tested. Results of 5 years of ground exposure of materials used to fabricate the 206L components are presented. Results of tests on three S-76 horizontal stabilizers and seven tail rotor spars are presented. Panels of material used to fabricate the S-76 components that were exposed for 4 years have been tested and results are presented. |
Automotive Mini Disc Changer Mechanism | A new automotive Mini Disc (MD) changer mechanism has been developed which fits a 1 DIN size chassis. This mechanism, mainly consisting of a disc change mechanism and an anti-vibration mechanism employing a floating disc drive unit system, offers a high vibration resistance, quick disc change capability and a size small enough to set a unit in an instrumental panel (I/P). |
ITS, A New Restraint System for Side Impact Protection | The Inflatable Tubular Structure (ITS) is a safety system intended to provide head protection during side-impact car accidents. The ITS is an inflatable device fixed at two points; at the front end, to the A-pillar, and at the aft end, to the roof rail behind the B-pillar. It is stowed over the side window under the trim of the A-pillar and the headliner. At one end, a gas generator is electrically connected to the side-impact crash-sensing system which inflates the ITS when needed. The ITS is fabricated in a unique way so that, upon inflation, its diameter greatly increases and its length correspondingly decreases. This causes the ITS to pull itself out of its stored location over the side window into a straight line between its anchor points. The ITS thereby forms a taut semi-rigid structural member across the window opening. The ITS is brought to a pressure higher than an air bag, and is unvented so that, even upon the cooling of the gas, it retains its position independent of window glass support to provide protection in secondary collisions and rollovers. |
Study of Whistles with a Generic Sidebranch | The coupling of shear layer instabilities with the acoustic resonances at the interface of two ducts, a main duct and a connecting sidebranch, leads to whistle noise. The present study investigates experimentally the mechanism of such pure tone noise. A generic sidebranch adapter is fabricated to allow for: (1) the ability to mount downstream of the throttle body in the induction system of a production engine; (2) the adjustment of sidebranch length; and (3) the changes in the diameter of the branch duct. Experiments are conducted both in a flow facility and an engine dynamometer facility for the same set of flow rates. The correlation of the whistle noise between these two facilities is examined in terms of frequency and the dimensionless numbers, including Strouhal and Mach. |
Adaptive Camouflage | Lightweight optoelectronic systems built around advanced image sensors and display panels have been proposed for making selected objects appear nearly transparent and thus effectively invisible. These systems are denoted "adaptive camouflage" because unlike traditional camouflage, they would generate displays that would change in response to changing scenes and lighting conditions. |
E-BEAM Treatment of Organically Contaminated Water | Energetic electrons injected into water abundantly create short-lived radicals that initiate rapid reactions. This leads to the break-up of organic contaminants into harmless products. The process works without catalyst (or other consumables) at ambient temperature and pressure. It is highly energy-efficient. We discuss preliminary results concerning removal of trichloro-ethylene, chloroform, benzene, and toluene using an electron beam (E-BEAM) system. On the basis of these results, we review the development of a compact E-BEAM system that can be used in space inhabitation and long-term space travel. Portability is achieved by using a relatively low beam energy, ~250 keV. We discuss newly available electron transparent windows, the development of a high-efficiency accelerator and power supply that control the power consumption to a level acceptable by NASA standards. |
A Semi-Empirical Approach for Modeling Greenhouse Surface Wind Noise | A CAE procedure for modeling the aerodynamic excitation of greenhouse surface vibration and its reradiation as noise is described. The procedure begins with a description of the steady flow over the surfaces. This is used as a basis for estimating the spatially varying unsteady pressure loading. The approach is semi-empirical, utilizing normalized pressure data collected through wind tunnel testing of production vehicles. The unsteady pressures are utilized within a normal mode analysis to predict vibration of the greenhouse panels. Interior noise associated with the panel vibration is estimated from a statistical energy analysis model. We show that contributions of multiple surfaces can be significant. |
Booming Noise Analysis in a Passenger Car Using a Hybrid-Integrated Approach | A hybrid-integrated approach is presented to analyze the structure-borne booming noise in a passenger car. We identify the critical noise transfer path from the engine to the target by the transfer path analysis. However, it does not give the answer for why the noise transfer function is so high at that path. Therefore, an integrated approach which applies the analysis tools systematically is presented. The running mode analysis gives us the operating motion of each component in the body structure. However, there is no evidence that the components that vibrate severely are the sources of this problem. The modal characteristics from the structural modal test enable us to describe the real motion of the body completely in terms of the structural modes. Similarly, the acoustic modal characteristics from the acoustic modal analysis describe the fundamental behavior of the cabin cavity. The introduction of the experimental running mode data of the structure to the acoustic finite element model makes the hybrid analysis possible. Through the structural and the acoustic modal analysis, we verify the mode that contributes to the booming noise. The panel contribution analysis points out the components that have the greatest influence on the booming noise. The modification of the body based on the results of the hybrid-integrated approach results in the great decrease of the noise level. |
Development of Vehicle Underbody Acoustic Holography | Acoustic holography is adopted in identifying the noise sources of a vehicle's underbody. Wind noise from a vehicle's underbody accounts for a large portion of the overall noise level due to the complex flow structure. Current study presents the development process of acoustic holography in the vehicle underbody. Difficulties associated with using acoustic holography as well as the method to eliminate the effect of sound reflection will be addressed. |
Experimental and Hybrid Modeling of the Medium Frequency Behaviour of Car Panels | This paper discusses an approach to identify critical car panels and to derive detailed experimental models for these critical panels. The research was conducted in the framework of the Brite/Euram project SALOME and the EUREKA project HOLOMODAL. The panel identification method is based on a numerical or experimental contribution analysis, assessing the partial noise contributions of individual panels to the interior noise. The second step in the approach consists of the derivation of detailed modal analysis models for the critical panels. A novel Electronic Speckle Pattern Interferometry (ESPI) system was developed, and integrated in a classical CAE system. The components of this system are briefly reviewed, and their application to several industrial cases is shown. |
Plastic Product Implementaion into Production -Steps from Concepts to Production Reality | The high temperatures associated with paint curing of automobiles fenders causes dimensional variation at the door and hood areas. This paper details the experimental techniques used to study the dimensional changes in fenders after they are processed and assembled “online”. Specific dimensional changes are presented and recommendations for computer-aided -engineering predictions are enumerated. Current work to reduce dimensional variations is described. |
Evaluation Methodologies for Automobile Side Impact Development | A comprehensive strategy for applying quasi-static and dynamic tests in the development of automobile side impact protection systems is presented. The approach is geared towards providing an understanding of how vehicle components relate to occupant protection as measured by the FMVSS 214 dynamic side impact test. These test methods are viewed as being complimentary, rather than competitive, tools to be employed in the overall strategy. The approach begins with obtaining detailed data from an FMVSS 214 dynamic test. Additional instrumentation is required so that the results of the test can be used to form the basis for setting conditions for subsequent quasi-static and dynamic tests. The Composite Test Procedure (CTP) is an integral part of the process. As described here, the CTP can be conducted under three different methods; three step procedure, continuous computer control, and continuous manual control. The principal value of the CTP method is to obtain spatial relationships within the door structure, overall force-deflection properties of the vehicle body structure, and input for a simplified, linear spring mass model to represent the FMVSS 214 dynamic test. Door structures are tested to provide a preliminary evaluation of door modifications, including both structure and trim panel, without resorting to full vehicle body development and build. The methods for door tests include both quasi-static, where the door structure and trim panel are evaluated, and dynamic (sled), where door trim panels are evaluated. Results obtained from these component tests can be related to full scale crash testing through mathematical modelling. The complimentary nature of these test methods is then discussed relative to improving performance in an FMVSS 214 dynamic test. A flow chart showing the relationship to a complete vehicle development program is presented and discussed. |
Transient Vibration Analysis During the Door Closing by Using the Laser Holography Method | The door closing sound is one of the important quality of a vehicle, and it is useful to study the improvement method of closing sound. As a step to clarify the relationship between the door structure and closing sound, it is attempted to correlate the formation of closing sound with the vibration, and explained that the effect of structural modification aimed to improve the closing sound from the viewpoint of vibration. First, the formation process of the vibration during the door closing is clarified through the analysis method of transient vibration using the pulse laser holography. And the quality of closing sound are evaluated based on the time historical fluctuation of frequency characteristics. Next, the correlation between the closing vibration and sound are studied, and for the case of that the closing sound are changed by the structural modification, the correlation are confirmed. |
The Corrosion Resistance of Organic Composite-Coated Steel Sheets | In order to investigate the corrosion resistance of organic composite-coated steel sheets ( OCS ) in a real automotive environment, many kinds of corrosion tests were performed on test pieces and real automotive doors. Tests with a corrosive solution including iron rust were introduced to simulate the real corrosive environment of automotive doors. The relationship between the components of OCS and the corrosion resistance in the rust-including tests was examined. In addition, electrochemical studies were performed. Results indicate OCS has much better corrosion resistance than plated steel sheets with heavier coating weight in all tests. OCS shows excellent corrosion resistance in rust-free corrosive solution, however, some types of OCS do have corrosion concerns in rust-including tests. It became clear that these OCS types have an organic coating with lower cross-linking. With respect to the components of lower cross-linking OCS, Chromate coating has little effect on corrosion resistance in rust-including solution. On the other hand, an organic coating with higher cross-linking shows remarkable improvement of corrosion resistance in rust-including test solutions. Therefore, it is likely that thin organic coatings are susceptible to damage by rust including test solution. Electrochemical measurement actually shows that impedance of OCS after exposing in rust-including solution is lower than before exposing. Consequently, the rust-including tests did simulate the real automotive corrosive environment. It is important to use a proper organic coating with high resistance against rust, because rust exists in real automotive corrosive environments. |
Perforation Corrosion of Automobiles - Field Car and Laboratory Investigation | In order to clarify the effect of design and materials of the hem as well as the climatic factors on perforation corrosion of the automobile doors, field car and laboratory investigation has been carried out Field car investigation revealed that corrosion of the hem can be minimized by using two side galvanized steel plus adhesives. The ratio of wet/dry environment was evaluated in laboratory on hemmed sample, and it was found that the design of the hem in conjunction with the various wet/dry ratio affected the corrosion rate differently. |
Flexvalve: An Innovation in Air Flow Control | This paper describes a flexible-film bladder, mode door. An air line is attached directly to the flexible valve through the mode housing or air duct for vacuum or positive pressure actuation. This technology addresses the need for more compact designs, part reduction and weight savings. It is designed to replace current mode valve doors, actuators and associated brackets. The propounded benefits of this design are outlined along with design considerations and part/system validation testing. |
Estimation of the Noise and Vibration Response in a Tractor Cabin Using Statistical Energy Analysis | The purpose of this paper is to establish a method of predicting the noise and vibration of tractor cabins in the engine-idling state by using Statistical Energy Analysis (SEA). At first, an analytical model of a tractor cabin is constructed, and power flow equations are formulated for the tractor cabin. To solve these equations, SEA parameters are estimated experimentally and analytically. These parameters are the modal density, loss factor, coupling loss factor, and input power. With these parameters, the noise and vibration responses of the tractor cabin are calculated. Good agreements are found between the analytical and experimental data. |
Maturing Fiber Reinforced Thermoplastic Technology for Automobile Body Structural Applications | With the increasing emphasis on fuel efficiency and environmentally friendly vehicles, much effort is being directed by the auto industry to develop efficient, lightweight and alternative-powered vehicles. One of the ongoing research programs at DaimlerChrysler's Liberty and Technical Affairs is not only aimed at reducing the overall weight of the automobile body structure, but also reducing the cost of manufacturing it. In addition, an automobile body structure needs to meet the requirements of noise, vibration and harshness (NVH), durability, crashworthiness and recyclability. The objective of this paper is to provide a review of the ongoing research and development activities leading to an automobile body structure that meets the above objectives. The paper highlights the many different technology development challenges faced during the process. Discussions of the choice of material systems, injection molding of very large body structural panels using these material systems, their applications to different products, cost implications and supplier issues are included in this paper. |
Rapid Development and Deployment of Dynamic Graphical Human-Machine Interfaces Within Automotive Environments | Emerging ‘glass’ displays make possible the benefits of Super Integration (SI) including weight, volume, and part count reductions as well as quality, reliability, serviceability, NVH, and manufacturability improvements [1]. This paper discusses an alternative to the hand-coding of displays aimed at facilitating the iterative development of Human-Machine Interfaces (HMIs) and the rapid generation of small-footprint, high-performance embeddable code for use in development, testing, simulation, documentation, and actual product environments. The process of code generation and rehosting at the heart of this technology will be described as will the architecture of the resulting software. Implementation experience will also be cited. |
Optimizing Sensor and Actuator Arrays for ASAC Noise Control | This paper summarizes the development of an approach to optimizing the locations for arrays of sensors and actuators in active noise control systems. A type of directed combinatorial search, called Tabu Search, is used to select an optimal configuration from a much larger set of candidate locations. The benefit of using an optimized set is demonstrated. The importance of limiting actuator forces to realistic levels when evaluating the cost function is discussed. Results of flight testing an optimized system are presented. Although the technique has been applied primarily to Active Structural Acoustic Control systems, it can be adapted for use in other active noise control implementations. |
Intrusion Resistance Test Development for Automotive Glazing | Consumers worldwide are demanding intrusion resistant automotive glazing. In response, carmakers are installing laminated side and rear glazing for enhanced protection. To insure enhanced protective glass (EPG) performance, a test is being developed to measure intrusion resistance in three simulated break-in modes. The three test modes are: glazing point attack; exterior impacts to penetrate the glazing or separate it from the vehicle body; continuous force to pull the glazing out of the body. The strength of the glazing and the strength of the glazing/vehicle attachment are both important for intrusion resistance. An intrusion resistance test method is recommended. |
Establishment of Stamping Process Windows | A stamping process window is a set of ranges of the critical input variables in the process. Quality parts can be produced only if all of these variables fall within their respective ranges. To achieve this, the window has to be wide enough and the process properly located within the window. In this paper, various input variables in stamping are examined and the variables that have to be strictly controlled are identified. The establishment, transfer, adjustment, protection, deterioration and re-opening of stamping process windows are described. Examples from production are presented. |
Measurement and Evaluation of Aerodynamic Noise | Recently, aerodynamic noise which originates in the flow of the body surroundings is actualized as a main cause of an automobile interior noise when running at high speed, because engine, power train and tire noise have been greatly decreased. Along with it, the measurement technology for the phenomenon elucidation and the evaluation has been demanded to decrease aerodynamic noise. In this paper, typical measurement examples of aerodynamic noise are introduced. These measurement technologies can be classified, and arranged to four types of measurements, which are flow, external noise, transmission psth and interior noise. This paper presents how the advancement of these measurement technologies has contributed to the aerodynamic noise elucidation. Moreover, the latest evaluation method of aerodynamic noise and the trend in the future to the demand of customer's many topics are introduced. |
Review of Aerodynamic Noise Prediction Using CFD | Recently, computational fluid dynamics (CFD) has made great progress. This paper reviews published papers on aerodynamic noise simulated by CFD and studies to what level CFD can predict aerodynamic noise for basic models and for applied models of automobiles. Based on noise generation mechanisms, aerodynamic noise is basically classified into two types, that is, noise induced by two-dimensional flow and by three-dimensional flow. As typical examples of noise generated by two-dimensional flow, wind throb at opened sliding roof, edge tone at the end of liftgate and aeolian tone generated by a cylindrical antenna are simulated by several computational schemes. As typical examples of three-dimensional flow, noise generated by A-pillar longitudinal vortex and noise from a side view mirror are computed by using a wing model and a actual vehicle, respectively. Noise by two-dimensional flow can be almost estimated whereas noise by three-dimensional flow cannot be predicted at sufficient accuracy especially in high frequency range. In order to predict noise with high accuracy it is necessary to improve computational techniques, based on noise data obtained by a carefully conducted wind-tunnel experiment which studies basic flow patterns with simple models. |
Life-Cycle Optimization of Car Components | The environmental impact of the automobile and its components is of growing importance not only in public debates but also in the complex decision making process regarding future car concepts. To calculate the environmental compatibility of car components BMW has developed various quantifying instruments and a holistic Life-Cycle Analysis (LCA) approach. The development phase significantly affects the entire life-cycle of a product. Suitable design criteria, recycling requirements and in-house standards have therefore been developed and established. One of the most important objectives in optimizing the environmental compatibility of the automobile is the realization of intelligent lightweight concepts. This means one has to find the most appropriate solution in terms of ecology and economy. Due to modern development processes car manufacturers and their suppliers have to intensify their cooperation also in this area. This paper presents some results of the cooperation between BMW and Hydro Aluminium for optimizing the life-cycle of various lightweight door concepts. Some general conclusions and „lightweight laws” have been deduced therefrom. This integrated life - cycle approach on a component base has the potential to become a practical development tool for managing the additional conflict of objectives with a view to the life-cycle ecology and economy of the automobile. |
Low Frequency Design Considerations for Automotive Audio Systems | The automobile interior is a challenging environment for the audio system designer. Yet, the literature related to automotive acoustics is sparse compared to the amount of published information on the acoustics of rooms and performance spaces. This paper addresses three areas of importance to the design of high fidelity autosound systems. First, it is difficult to accurately predict the nature of the listening acoustics in a car at low frequencies because complex interior geometries make mode calculations almost impossible. At the same time, the cabin interior introduces acoustic gain in the first three octaves of musical reproduction. Secondly, the car environment is subject to constantly changing levels of so-called road noise that mask musical material at low frequencies. Finally, a simplified model is proposed for the characterization of the car door as a loudspeaker enclosure. Measurement data are presented to illustrate the nature of low frequency gain in automobile cabins and to evaluate the feasibility of the proposed enclosure model. |