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Development of a Rigid Passenger Safety Compartment Made of Composite Material-Application for Front Door Frames

Based an extensive preparatory work and analyses, suggestions have been drawn up with regard to solutions for front door frames in the following regions:- door hinge mountings, seat belt anchorage mountings of B pillars, cross sections for the top of A pillars. At the same time as the design work, FEM calculations should be carried out to ensure optimization of the concepts. Economy reasons and experiences in production runs point towards a very strong fibre glass-reinforced door frames manufacutred in the SMC procress. The complete door frame is examined in comparison with geometrically similar sheet metal parts on a test frame and in the vehicle.

The Effect of Door Topography on Abdominal Injury in Lateral Impact

Seventeen left lateral impact experiments were performed using anesthetized swine to determine the biomechanics of injury production in this impact mode. Two series of eight animals were used and one animal served as a control. In the first series of experiments, rigid thoracic and pelvic loading surfaces were separated by an “interplate gap” of 20.3 cm (8”). In the second series of experiments, the interplate gap was filled by a rigid plate mounted flush with the thoracic and pelvic loading surfaces. Impact velocities ranged from 7.2 to 15.0 m/s (about 15 to 30 mph). Injury patterns for the liver, spleen, and rib cage were significantly different in the two series of experiments (level of significance > 90%). The causative factor responsible for the different injury outcomes was the interplate gap. The conclusion of this report is that loading-surface discontinuities can cause significant injury. Therefore, in design of side doors and interiors, consideration should be given to the location of surface indentations (such as map pockets) as well as surface protuberances (such as armrests).

The Importance of the Test Method in Determining the Effects of Door Padding in Side Impact

This study examines the influence of padding in thorax side impact response under free-flight impact and velocity pulse impact. It was found that padding reduces rib and spine accelerations in both types of impact. However, in free-flight impact, padding reduces chest V and VC response without significant deformation change, while in velocity pulse impact, padding reduces chest V but substantially increases VC and deformation. It appears that free-flight impact lacks spacing effect and the correct velocity profile to simulate the door/occupant impact in car-to-car side collision. On the other hand, velocity pulse impact has the essential characteristics of the door/occupant impact in car-to-car side collision and is a more suitable method for subsystem test.

Corrosion Protection of Galvanized Steel Sheet - Corrosion Investigation of Field Vehicle and Its Laboratory Evaluation Methods

For the accumulation of knowledge of perforation corrosion, three doors of three field vehicles made with one-side galvanized steel on the inside of the outer panels were investigated with some microscopic and analytical methods after 8 or 10 years’ field running in the snow-belt areas of North America. For these doors, perforations were found within the lapped part of the door hems. Outer panel perforation began as zinc layer corrosion of the inside surface of the outer panel at the lapped part and/or as “bent part” corrosion of the outer panel at the door hem. The inside of the outer panel lightly corroded at the open part in spite of the lack of primer on the inside surfaces of the outer and inner panels. The corrosion behavior of a lapped panel specimen test was studied and compared with that of investigated door hem corrosion. In the case of these doors, the test provided a result having a fairly good agreement with the field vehicle doors’ behavior.

Concept of a “Flexible” Combi Aircraft

An airframe manufacturer is compelled to include the requirements of the air cargo transport market, existing and anticipated, in the definition of its products- A combi aircraft, derived from the passenger version, requires configuration flexibility. With the addition of an aft located main deck cargo door, six (6) 96 in × 125 in pallets may be carried on the main deck. All six (6) pallets can be loaded to a 96 in high contour, with both lateral upper corners cut. A number of other ULDs can be accommodated, e.g the AHA container, up to the 20 ft pallet. The flexibility to adapt to market requirements and i.e. airline route networks is achieved by the convertibility from the typical passenger layout with six (6) to five (5) to four (4) pallet combi configurations up to an all-passenger mode, with particular attention to conversion times.

“Optimization” of Lower Deck Cargo Systems

The ability to carry cargo efficiently in passenger aircraft has influenced airline economics to the point that optimisation of the freight capacity is mandatory. This document discusses the alternative loading possibilities in defined Lover Deck Compartments and their doors to cater for current and future trends in ULD dimensions. As a result items for study centred on: 1) Optimisation of the available volumes Freight capacity resulting in the selection of “Pallets”-doors for both the Forward and AFT Compartments. Flexibility to meet Freight and Baggage requirements. Possible load arrangements to optimize aircraft C of G 2) Bulk Cargo Compartment Additional LD3 Container position in AFT/Bulk compartment to cater for an uneven number of Baggage container, allowing the carriage of an additional pallet. What is regarded as an optimum is presented.

Some Problems Concerning the Application of Sound Intensity Measurement to Automobile Noise Analysis

Even if the sound intensity measurement (SIM), the most advanced sound measuring technique, has been used in the field of automobile noise control for over 6 years, there are still many technical problems pending for further research. Some of the problems involving the influence of sound source frequency features on the measuring accuracy of sound intensity (SI), application of SI map inside the automobile cab and the use of taperecorders are discussed in this paper and some useful results are presented.

Chassis Dynamometer Simulation of the Tractive Resistance of Vehicle

This paper deduces a mathematical model to determine the road load force using coastdown techniques, and determines the model parameters using numerical integration by analysis in theory and verification in practice. On the basis of analysis and comparison of the vehicle load on the road and on a chassis dynamometer, it gives the relevant transformational relation, constitutes a set of new method of test and computation to determine the road load force by simple coastdown test and provides the foundation for vehicle performance test in doors.

Quieter rides

SAE 100 Future look: Cell phones, high-end stereos, satellite radios, navigation systems, CD and DVD players. No it's not necessarily the inventory at your local consumer-electronics store. These are just some of the audio-related devices used in cars today, and surely these and others will be staples in the car of tomorrow. As a result, automobiles will have to become significantly quieter, keeping the noise out so passengers inside can enjoy the latest advances in communications and entertainment technologies.

Advances in Diesel Protection Systems

Over the last several years, the use of D.C. solenoids and electronics to ensure safe and reliable diesel engine shutdown has grown significantly. These devices are used during normal engine operation and in the event of a malfunction. Applications include both on and off-highway vehicles as well as generator sets. The use of key start in off-highway equipment has also had a major impact on the use of D.C. solenoids. Reliability has been improved through the use of computerized coil design, constant volume protection boots, external switching and electronic timers. Testing methods (for vibration. shock and temperature extremes) have been developed to promote trouble free product life.

Numerical Simulation of Door Frame Deformation due to Aerodynamic Suction Force

Negative pressure around the front pillar of a vehicle travelling at high speed deforms the door frame in the outward direction. This causes the aspiration noise. Finding a method for the reduction of the resulting air aspiration noise is a goal of this study which analyzes this phenomenon. The method proposed here can be applied to find effective measures to reduce aspiration noise at the early stages of vehicle development.

Road Noise Reduction Using Transfer Function Synthesis Method

An experimental simulation method has been developed for predicting the noise and vibration characteristics of a complete vehicle when body frame stiffness is changed. This method was developed by means of an improved transfer function synthesis method. Advantages over numerical simulation methods, such as finite element analysis include dramatic reductions in computation time. This experimental method is also very easy to carry out with a few measurement data. By applying this method to investigate the effects of stiffness changes of different vehicle components on low frequency road noise, effective ways of reducing road noise were proposed in the first stage of vehicle development.

Aeroacoustics Development at Pininfarina

This paper reports recent developments made at Pininfarina in the aeroacoustic field with the aim of reducing the background noise in the test section of its full scale wind tunnel as well as for improving the measuring techniques which are used during the acoustic development of new cars. The first part of the paper describes the changes made to the wind tunnel drive-line, i.e. new motor, new low-noise fan and new acoustic treatments. The new background noise levels are reported and compared with the old values, already published in ref. (2). The second part describes the three acoustic techniques (acoustic intensimetry, acoustic holography and acoustic mirror) which have been developed or improved in the meantime, to measure the exterior noise of new cars from the first stage of their design. Examples of results of these measurements are reported as well as an indication of the capabilities and limitations of each technique.

Application of Derived Characteristics from Dynamic Test Data for Simulation of Car-to-Car Side Impacts Using a Lumped Mass Approach

Lumped spring/mass modelling approaches are described for the simulation of structural and occupant response in side impacts (driver side). Special attention is placed on modelling techniques and procedures for mass assignments, derivation of force versus deflection characteristics and model redundancy checks. The force versus deflection characteristics were derived from dynamic test data and the inverse solution of the nonlinear equations of motion for the system. Unique procedures are also presented for estimating rib to spine damping characteristics and driver body segment internal and contact compliances. Three models are presented and evaluated. Simulations showing the effect of changes in striking car stiffness, struck car stiffness-, impact angle, impact speed, occupant to door clearance and interior door pad thickness and strength are presented and discussed. Model limitations and various factors affecting the applicability of the methodology are also discussed.

Vehicle Testing with Flat Surface Roadway Technology

MTS Systems has built and operated a vehicle test system called the Flat-Trac® Roadway Simulator. The system measures the handling characteristics of a running automobile while holding it stationary in a laboratory. The system can also test the vibration and durability characteristics of an automobile due to driving on rough roads by moving the surface beneath each tire vertically. The automobile is driven as on the road with the machine providing relative motion by moving a flat surface beneath each tire. This paper presents the results of operating a vehicle on the system with a rough road simulated during maneuvering.

Accelerometers Equivalency in Dummy Crash Testing

The National Highway Traffic Safety Administration has initiated research to develop performance specifications for dummy-based accelerometers in the crash test environment, and to provide criteria for defining and establishing equivalent performance among accelerometers from different manufacturers. These research efforts are within the general guidelines on transducer equivalency outlined in the current revision of the Society of Automotive Engineers recommended practice, Instrumentation for Impact Test, SAE 211/2 March 1995. Representative data from vehicle crash and component level tests have been analyzed to determine the acceleration levels and frequency content in a realistic dynamic environment for dummy-based accelerometers. A series of component level tests (head drop calibration tests) and initial calibration tests (using a State-of-the Art commercially available comparison shock calibrator) were performed with a selection of accelerometers to determine dynamic response variability. A limited series of glazing tests is presented with discussion of the implications that high frequency accelerometer resonance response has on accelerometer selection and data acquisition practices. The results of these tests and recommendations for possible test procedures for evaluating accelerometer performance and equivalency in the crash test environment are presented.

The Future of Sunvisors

A brief history of the sunvisor is laid in chronological order as well as the design of passenger cars with relation to shape and aerodynamic characteristics. A description of the slope of the windshield and the subsequent flattening of the roof line is also described and illustrated. The changing role of the visor is given in detail and describes today's visor and it's function and features. As the vehicle shape changes, so too, the visor and it's mission, of necessity, must accommodate this natural evolution. The role of the visor is shifting from that of sun blocker and feature support, to that of safety component. Described herein are the materials and processes that will be the future visor. Also, the end of the sunvisor as we know it is mentioned and how that will be accomplished. The main thrust of tomorrow's visor is impact management and safety for the occupants.

Research on the Evacuation Readiness of Bus Crews and Passengers - Investigation of the Effect of a New Type of Exit

This research was conducted to propose appropriate emergency exits for bus crews and passengers. We developed the improved emergency exit based on the results of current bus exit performance tests, and investigated its effect on evacuation readiness. Tests employing human subjects were conducted to measure the time required to evacuate using the improved emergency exit. The subjects' psychological responses during evacuation were also studied to identify any evacuation problems. We also carried out tests of group evacuation through windows in a current bus to obtain the relationship between the evacuation time, the number of evacuation subjects, and the number of windows. The results show that the improved emergency exit is effective in improving evacuation readiness. It is clear that there is a positive correlation between the evacuation time, the number of subjects, and the number of windows.

Statistical Energy Analysis of Airborne and Structure-Borne Automobile Interior Noise

This paper describes the application of Statistical Energy Analysis (SEA) and Experimental SEA (ESEA) to calculating the transmission of air-borne and structure-borne noise in a mid-sized sedan. SEA can be applied rapidly in the early stages of vehicle design where the degree of geometric detail is relatively low. It is well suited to the analysis of multiple paths of vibrational energy flow from multiple sources into the passenger compartment at mid to high frequencies. However, the application of SEA is made difficult by the geometry of the vehicle's subsystems and joints. Experience with current unibody vehicles leads to distinct modeling strategies for the various frequency ranges in which airborne or structure-borne noise predominates. The theory and application of ESEA to structure-borne noise is discussed. ESEA yields loss factors and input powers which are combined with an analytical SEA model to yield a single hybrid model. Results from model validation and correlation with measured data are presented.

The Creation of a Car Interior Noise Quality Index for the Evaluation of Rattle Phenomena

Rattle noise produced in the vehicle interior due to broadband excitation by road irregularities is a major concern with respect to driving comfort, and therefore has become one of the most important topics of acoustic development in recent years. A quantification i.e. measurement of this rattle noise is of fundamental importance for systematic development work and production control. Common noise level measurements (dB, dBA, etc. ) do not represent the rattle character in the vehicle interior as revealed during initial investigations. To overcome this problem and to substitute the subjective assessment with a combination of measurable parameters, the psychoacoustic software AVL-EAR was applied to create an Interior Rattle Quality Index. Based on more than 40 different vehicles that have been subjectively assessed by approximately 70 test persons, the index was generated by means of multiple pair comparisons and statistics on measurement data. The index correlates appropriately with the subjective rattle impression, with correlation coefficients of about R = 0.88 for the individual vehicle categories.

Acoustic Performance Analysis of an Air Handling System

In the present study, the acoustic performance of an automotive air handling system is analyzed using computational aeroacoustics methods. The purpose of this study is to develop a comprehensive method to quantify noise sources and predict sound quantities at any location in the system as well as in the exterior field. Flow of air and vibration of structures are solved simultaneously in the time domain. Results are then postprocessed to derive sound sources. Sound pressure levels at desired locations in the exterior field are then predicted. Predictions were compared with preliminary test data. Also compared is a simulation of the same system using a Helmholtz equation solver, but without taking into account the average fluid flow.

Experimental Body Panel Contribution Analysis for Road Induced Interior Noise of a Passenger Car

This paper describes more in detail the methodology, the measurements and the results of the ASQ method. The Airborne Sound Quantification method aims at identifying the acoustical contribution of the different body panels surrounding a cavity. The contribution of different body panels is the product of the acoustical strength (or volume velocity) of each panel with the corresponding acoustic transfer function between the panel and the interior microphone position. These volume velocities are the product of the corresponding normal velocity and the surface. The normal velocity has been measured by means of accelerometers attached to the different subpanels. In the next step, the acoustical FRF's are measured in an indirect way using the reciprocity principle. This means that the pressure response at all the subpanels is measured when the acoustical excitation takes place at the target interior noise microphone position. A high quality low frequency sound source has been used. Finally, this synthesized interior noise has been compared with the directly measured interior noise. The correlation between both proved to be very good and the most dominant body panels have been successfully identified.

Determination of Vehicle Interior Sound Power Contribution Using Sound Intensity Measurement

For vehicle interior noise abatement and noise treatment, it is desirable to quantitatively determine sound power contribution from each vehicle component because: (1) Sound packages can be designed with maximized efficiency if sound power contribution into a vehicle is known; (2) Acoustic leakage inside a vehicle can be determined by comparing sound power contributions from adjacent vehicle components; and (3) Sound power flow information can be used to verify Statistical Energy Analysis (SEA) model. Simple sound pressure measurement does not produce any information about sound power flow and is unsuitable for these purposes. This paper describes an in-situ determination of sound power contribution inside a vehicle using sound intensity measurements. Sound power contribution from each vehicle component was determined for engine noise at idle speed. Acoustic leakage in the vehicle was also determined. Practical considerations on the selections of measurement surface, measurement distance, and length of sound sampling time are presented. Sound intensity instrumentation and difficulties associated with near field sound intensity measurements are discussed.

Aeroacoustic and Acoustic Testing of Automobile Side Windows

Several different automobile windows were tested for transmission of noise Bench-scale flow noise tests, full-scale wind tunnel flow noise tests, and acoustic tests were performed The windows tested were the front side windows of a Chrysler sedan The transmission of external airborne noise was measured in a hemianechoic chamber at the Chrysler Technical Center A loudspeaker was used as a white noise source The transmission of the white noise into the vehicle interior was measured Aeroacoustic or flow noise tests were performed in the Chrysler Wind Tunnel in Chelsea, Michigan The test car was placed in a 112 km/hour flow and the resulting flow-induced noise was measured in the vehicle interior Bench-scale flow noise tests were performed at the Cornell University Low Noise Wind Tunnel, using the same set of window constructions The paper describes the results of all three types of tests The bench-scale test data from the Cornell University Wind Tunnel correlated well with the corresponding data measured in the Chrysler wind tunnel

Glazing for Motor Vehicles - 1995

THERE ARE four viable types of glazing for use in motor vehicles: 1. Laminated 2. Tempered 3. Laminated glass-plastic 4. Tempered glass-plastic Laminated and laminated glass-plastic glazing will pass the MVSS Standard 205 for windshields, and all four types can now be used in side and rear windows. Laminated and to a limited extent laminated glass-plastic windshield glazing has been used in production, but the glass-plastic was not durable enough so it has been discontinued. Tempered glass has been used exclusively in side and rear windows since the early 1960's due to the strength requirements, and is the best choice for these locations. Recent experimental attempts to use tempered glass-plastic glazing in side windows have been unsuccessful due to high neck loads, and additional hazards in the designs. Even more important is the lack of durability due to more severe exposure than the glass-plastic windshield experienced.

A Structural Instrument Panel from Glass-Mat Thermoplastic for the Small-Car Market

Designers and engineers encounter many challenges in developing vehicles for the small-car market. They face constant pressure to reduce both mass and cost while still producing vehicles that meet environmental and safety requirements. At the same time, today's discriminating consumers demand the highest quality in their vehicles. To accommodate these challenges, OEMs and suppliers are working together to improve all components and systems for the high-volume small-car market. An example of this cooperative effort is a project involving an integrated structural instrument panel (IP) designed to meet the specific needs of the small-car platform. Preliminary validation of the IP project, which uses a compression-molded, glass-mat-thermoplastic (GMT) composite and incorporates steel and magnesium, indicates it will significantly reduce part count, mass, assembly time, and overall cost. Investigation of the IP system by finite-element analysis (FEA) indicates the system demontrates the ability to pass Federal Motor Vehicle Safety Standard (FMVSS) 208 requirements for femur load and OEM requirements for noise, vibration, and harshness (NVH), while fulfilling consumer expectations. The concept-to-validation program, described in this paper, was undertaken by engineers and designers from two materials suppliers and one OEM organization to investigate the viability of the structural IP system.

Modeling of Airborne Tire Noise Transmission into Car Interior by Using the Vibro-acoustic Reciprocity and the Boundary Element Method

In this paper, the vibro-acoustic transmission characteristics are investigated in the view point of the airborne noise in the interior cavity due to the tire wall vibrations. The analysis is carried out by categorizing the airborne noise transfer path into the two separate consecutive events. First, the noise transfer from the vibrating tire wall to the exterior car panels is modeled by using the direct boundary element method (BEM). To this end, after discretizing the whole geometry of exterior body panels, tires, and ground into BEM models, vibro-acoustic transfer characteristics are investigated at several frequency components associated with the cavity resonances of tire. Here, cavity resonance frequencies of tire are estimated by BEM and the distribution of tire wall vibrations excited by a special vibro-acoustic source is measured at those frequencies. Acoustic pressure distribution over the exterior car panels can thus be predicted and the contribution of local vibrational velocity of tire wall to car panels are estimated by the vectorial summation of resultant acoustic pressures. Second, vibro-acoustic transfer functions between the various points of car panels and the receiver's ear position in the car interior is measured by utilizing the vibro-acoustic reciprocity principle. Combining these two transmission path models in series, the airborne noise transmission from tire wall vibration to driver's ear can be analyzed. From the results, contributions of tire wall vibration to the interior noise can be estimated and the main possible transmission paths of airborne tire noise can be identified.

A CAE Methodology for Reducing Rattle in Structural Components

Squeak and rattle has become a primary source of undesired noise in automobiles due to the continual diminishment of engine, power train and tire noise levels. This article presents a finite-element-based methodology for the improvement of rattle performance of vehicle components. For implementation purposes, it has been applied to study the rattle of a glove compartment latch and corner rubber bumpers. Results from the glove compartment study are summarized herein. Extensions to other rattle problems are also highlighted.

Computer Simulation of In-Vehicle Boom Noise

In the design of an automobile, an important consideration is to minimize the amount of “boom” noise that the vehicle occupant could experience. Vehicles equipped with four cylinder engines can experience powertrain boom noise in the 40 to 200 Hz frequency range. Boom noise can also be generated by road input, and it is just as annoying. In this paper, a CAE methodology for predicting boom noise is demonstrated for a vehicle in the early design stage in which only 3-D CAD geometry exists. From the CAD geometry, a detailed finite element (FE) model is constructed. This FE model is then coupled with an acoustic model of the interior cavity. The coupled structural-acoustic model is used to predict acoustic response due to powertrain inputs. As a part of the detailed design process, various design modifications were considered and implemented in the vehicle system model. Many of these modifications proved successful at reducing the boom levels in the vehicle. A comparison of responses for baseline and modified designs will be shown. Comparisons will also be made to measured response from prototype and production vehicles.

Tire Noise Reduction Treatment for a Passenger Car Used as a Tow Vehicle for Pass-by Noise Testing

The possibility of using a trailer to measure pass-by sound levels of tires has been limited by the tire noise generated by the tow vehicle. In order to verify the viability of the trailer method for passenger car tires, a trailer and tow vehicle were constructed and tested. A reduction goal of 3 dB(A) below the tow vehicle and trailer with the test tire was required for the tow vehicle alone. The noise reduction treatment, designed and developed for this project, successfully reduced the tow vehicle sound level enough to permit the coast-by trailer method to be used for tires as small as P145/80R13.

Design, Construction and Application of a World Class Vehicle Acoustic Test Facility

The allowable noise emission of vehicles has been continuously reduced by legislation in the past. In parallel the interior noise level and noise quality have been improved dramatically. Even small size cars show today remarkable sound quality. This general effort to reduce vehicle noise has brought about a reduction in the combined effects of noise and vibration on the passengers. Today's vehicles exhibit more closely matched noise contributions from the engine, transmission, inlet and exhaust systems as well as road inputs via the suspension. For a further improvement of vehicle noise levels and sound quality, simple reduction of individual noise sources is no longer a suitable approach. A full understanding of their combined effect on vehicle noise is required, for cost-effective and production-feasible solutions to lead to the desired noise reduction or the achievement of a typical “Brand Sound” through sound engineering. For such development work, a vehicle acoustic test facility is absolutely indispensable. To qualify as a full partner in the Automotive Industry, AVL has established a vehicle test facility equipped with the very latest technology, capable of handling vehicles under all operating conditions. In this paper the vehicle acoustic test facility will be presented in detail, illustrating its use for noise reduction development activities ranging from reducing individual vehicle noise sources via trouble-shooting to sound engineering.

The Laboratory Simulation of Tyre Noise

A laboratory technique has been developed for simulating high frequency tyre noise in a car. The technique characterises air-borne tyre noise and its transmission from the tyre and road contact patch to the occupant positions. The technique could be applied to the rapid definition of design modifications in a laboratory environment and the generation of competitive criteria for vehicle benchmarking.

Noise Radiation from Axial Flow Fans

A semi-empirical formula [1] for predicting noise spectra of an engine cooling fan assembly is developed. In deriving this formulation it is assumed that sound radiation from an axial flow fan is primarily due to fluctuating forces exerted on the fan blade surface. These fluctuating forces are correlated to the total lift force exerted on the fan blade, and is approximated by pressure pulses that decay both in space and time. The radiated acoustic pressure is then expressed in terms of superposition of contributions from these pressure pulses, and the corresponding line spectrum is obtained by taking a Fourier series expansion. To simulate the broad band sounds, a normal distribution-like shape function is designed which divides the frequency into consecutive bands centered at the blade passage frequency and its harmonics. The amplitude of this shape function at the center frequency is unity but decays exponentially. The decay rate decreases with an increase in the number of bands. Thus, at high frequencies the narrow bands merge to form a broad band-like spectrum. The noise spectra thus obtained are compared with measured ones from three different types of axial flow fans running under various conditions. The calculated total sound pressure levels from these fans are also compared with the measured ones and those obtained by using the fan laws.

Acoustic Optimization of HVAC Systems

For HVAC systems this paper describes “excellent” acoustics and criteria and tools for acoustic evaluation. Focusing on the HVAC subsystem “air flow”, it further outlines four columns on which acoustic is based. Finally this paper discusses aspects how the vehicle design process which can facilitate acoustic optimization of HVAC systems.

Piezoelectric Actuator Configuration Optimization for Active Structural Acoustic Control in Aircraft

This paper has presented a technique for the determination of an optimal configuration of fuselage mounted piezoelectric actuators for active structural acoustic control of interior noise in aircraft. The technique has demonstrated much potential in preliminary experiments where actuators were configured to couple into the first principal component of the acoustically coupled fuselage vibration. In this test, average reductions of 6 dB at the error microphones and 4 dB at five auxiliary microphones were observed for a pure tone disturbance at the left forward engine pylon of a business jet. This disturbance was used to simulate an oscillating force due to engine unbalance.

Correlation of Various Test Methodologies with Vehicle Seat Acoustical Performance

Quietness is a primary metric of vehicle interior sound quality. Seats have always had the potential of enhancing interior quietness. An acoustic study was undertaken with seats to determine the similarity of result rank using different acoustic test methodologies. The component of test were seats for a production minivan. Nine complete seat sets underwent various acoustic tests. The nine seat sets were of various fabrics and construction. The acoustic tests were normal incidence sound absorption, random incidence sound absorption, in-vehicle sound absorption and artificial source noise reduction. A comparison of acoustical performance rank of seat sets from the various tests were obtained. Ranks obtained from various materials with in laboratory acoustical tests showed consistency.

An Assessment of the Tire Noise Generation and Sound Propagation Characteristics of an ISO 10844 Road Surface

A road surface complying with the new International Standards Organization (ISO) specification was installed at an Arizona test facility (DPG site) in the winter of 1995/96. As part of the acoustic qualification of this site, comparative tests were conducted between this new surface, a Society of Automotive Engineers (SAE) sealed asphalt surface and an existing ISO surface in Michigan (MPG site). Initial testing with one vehicle and tire combination indicated that the new ISO surface produced ISO 362-1994 passby and coastby levels about 2 dB lower than sealed asphalt. Relative to the Michigan surface, the levels for the new Arizona ISO surface were 3 to 3½ dB lower. These differences were much greater than expected based on previously published studies of these two test surface types. Since the new surface was constructed to the ISO specification and meet the physical requirements for sound absorption coefficient, porosity, and surface texture, further investigation was conducted to determine if sound propagation or tire noise generation differences accounted for the differences. Experimental work to understand this difference included the use of on-board sound intensity measurements to isolate tire noise generation under both acceleration and coast and static sound propagation tests to isolate surface reflective properties. Analytically, a sound reflection model was developed to predict differences in attenuation based on measured surface impedance data. Taken together, the results of this investigation support the conclusion that a majority of the differences observed are due to tire noise generation. However, in comparing the new ISO surface to the SAE, a significant portion was also found to be attributable to sound propagation differences.

NVH Research Facilities at The Ohio State University: Existing Facilities and Envisioned Enhancements

The automotive NVH research infrastructure at Ohio State includes the Center for Automotive Research, the Acoustics and Dynamics Laboratory, and the Gear Dynamics and Gear Noise Research Laboratory. This paper describes the facilities of these laboratories. Two unique existing facilities, namely the transmission error measurement of gears and a laboratory for the experimental measurement of engine breathing systems, will be emphasized. Also covered are the enhancements that are envisioned through a recent grant from the Ohio Board of Regents.

“Next Generation” Means for Detecting Squeaks and Rattles in Instrument Panels

Engineers doing squeak and rattle testing of instrument panels (IP's) have successfully used large electrodynamic vibration systems to identify sources of squeaks and rattles (S&R's). Their successes led to demands to test more IP's, i.e., to increase throughput of IP's to reflect the many design, material, and/or manufacturing process changes that occur, and to do so at any stage of the development, production, or QA process. What is needed is a radically different and portable way to find S&R's in a fraction of the time and at lower capital cost without compromising S&R detection results.

Statistical Energy Analysis for Road Noise Simulation

Statistical Energy Analysis (SEA) is being actively pursued in the automotive industry as a tool for vehicle high frequency noise and vibration analysis. A D-class passenger car SEA model has been developed for this purpose. This paper describes the development of load cases for the SEA model to simulate road noise on rumble road. Chassis roll test with rough shells was performed to simulate rumble road noise. Sound radiation from tire patch and vibration transmission through spindles were measured to construct the SEA load cases. Correlation between SEA model predictions and measured data was examined. Test and SEA result comparisons have shown that simulation of airborne road noise requires only a trimmed body SEA model, while simulation of structure-borne road noise may require SEA modeling of chassis components.

Panel Contribution Study: Results, Correlation and Optimal Bead Pattern for Powertrain Noise Reduction

To understand how the passenger compartment cavity interacts with the surrounding panels (roof, windshield, dash panel, etc) a numerical panel contribution analysis was performed using FEA and BEA techniques. An experimental panel contribution analysis was conducted by Reiter Automotive Systems. Test results showed good correlation with the simulation results. After gaining some insight into panel contributions for power train noise, an attempt was made to introduce beads in panels to reduce vibration levels. A fully trimmed body structural-acoustic FEA model was used in this analysis. A network of massless beam elements was created in the model. This full structural-acoustic FEA model was then used to determine the optimal location for the beads, using the added beams as optimization variables.

Statistical Analysis of Vehicle High Mileage NVH Performance

High mileage NVH performance is one of the major concerns in vehicle design for long term customer satisfaction. The current paper is concerned with performance analysis of high mileage vehicles which cover four automobile manufacturers and five vehicle families of the same weight class based on subjective evaluation data. The analysis includes the assessment of five vehicle families from the following aspects: overall and NVH performances, performance by individual attribute, degradation history of each vehicle family, performance variation within each vehicle family. Since the data are statistical in nature, statistical methods are employed, numerically and graphically, in the analysis. The performance categories which exhibit most degradation are identified. The analysis method presented in this paper is applicable to any high mileage vehicle fleet subjective data. The knowledge derived in the study can be used as a guideline in designing vehicles for high mileage NVH robustness.

An Engineering Approach to Sound Quality

The subjective quality of sounds is a topic of increasing importance in the automotive industry. The first consideration is to describe the perceptual characteristics of this quality by means of jury tests or appropriate metrics. Once a NVH problem is determined in terms of an appropriate Sound Quality description, an in-depth analysis of the underlying physical phenomena must be made and engineering solutions newel to be proposed and validated This involves: • the detailed analysis of the signal structure in the time, frequency and order domain and identifying the signal Components Critical to the relevant sound quality dimension • the Correlation of the critical signal components to specific sources noise or vibration transmission paths and vibro-acoustic system characteristics. Ultimately this should lead to the prediction of the effect of feasible modifications in sound quality terms through the use of engineering models. This is up to now however only possible for a limited set of NVH problems due to limitations of Current modelling methods. The above procedure will be reviewed for a typical selection of sound quality cases. • a road noise problem (broad-band signal) • the sound of a door-slam (transient signal) Finally an overview of present research on the level of modelling for sound quality will be given; and the Collaborative EC project “SOQCRATES” on automotive sound quality engineering will be presented

FE Analysis, Dynamic Test and Correlation of Vehicle Structures

Computer simulation using finite element analysis techniques was used to predict and improve the performance of vehicle components and structures. In order to determine the actual loading and validate the FE model, extensive physical testing which involved data acquisition and analysis was undertaken. The paper shows the application of FE analysis and testing with examples for optimization of an automotive wheel, drive line vibration, car body shell interior acoustics and a railway vehicle structure.

Acoustical Quality Control, Specifically Various Gear Wheels and Electrical Motors

The following describes a structure-borne noise measuring technology that is successful as an acoustical quality control for serial test. There are 2 examples for very efficient applications: 1.0 Already in 1981 the first full automatically working test decices have been installed. Since then more than 30 million step wheels for car gears were tested by this procedure. The rolling noise is judged by limit values with exact adjustable conditions. 2.0 The first “selfteaching”, computer-controlled electronics for electrical motors is working till today. Since 1985 the electrical and acoustical values of more than 10 million fans are tested automatically, whereby the tact rate per 2 fans amounts to 10 s.

Engineering Development and Performance of the Chrysler Dakota Fully-Integrated Thermoplastic Instrument Panel

A fully-integrated thermoplastic structural instrument panel (IP) system will be implemented on Chrysler's Dodge Dakota Truck Platform. The structural IP consists of a three-piece monocoque thermoplastic injection molded structure that replaces the traditional retainer, air delivery ducts, steel beams and reinforcements typically used in IP designs. Ribbed thermoplastic bolster systems have been incorporated as part of the energy management system. The structural IP provides the required stiffness to satisfy noise, vibration, and harshness (NVH) quality targets and the necessary strength and rigidity to effectively meet FMVSS No. 208 requirements for managing occupant and passenger air bag (PAB) deployment loading during 48 km/h (30 mph) frontal crashes. This paper discusses the engineering development process and performance of the Dakota structural IP system as predicted by finite element simulations and the correlation of the predicted behavior through frontal barrier vehicle crashes.

Body Electronics Area Network (BEAN)

This paper describes the multiplex communication protocol, BEAN (Body Electronics Area Network), developed for body control system on passenger cars which in recent years has increased the scope of multiplex communication. BEAN is based on a protocol developed in 1992 (SAE920231) but expands upon the performance in areas, such as the suitability of the ID system for increase of ECUs, the variable data length enabling the transmission of diagnostic data, and the transmission rate, while keeping the cost and radiation noise level low. The software size of BEAN is compact enough to be implemented by general purpose 8bit MCUs which have recently seen improvements in performance. The BEAN communication devices are available corresponding to the scale of the application and configuration of the ECU taking into account the software capability. This protocol was evaluated using simulation with the body control system on luxury passenger cars.

The General Purpose Work Station, A Spacious Microgravity Workbench

The General Purpose Work Station (GPWS) is a laboratory multi-use facility, as demonstrated during the Spacelab Life Sciences 1 (SLS-1) flight. The unit provided particulate containment under varying conditions, served as an effective work space for manipulating live animals, e.g., rats, served as a containment facility for fixatives, and was proposed for use to conduct in-flight maintenance during connector pin repair. The cabinet has a front door large enough to allow installation of a full-size microscope in-flight and is outfitted with a side window to allow delivery of items into the cabinet without exposure to the spacelab atmosphere. Additional support subsystems include inside cabinet mounting, surgical glove fine manipulations capability, and alternating or direct current power supply for experiment equipment, as will be demonstrated during Spacelab J. The GPWS, integrated and maintained in a double flight-rack, interfaces to spacelab systems including water cooling, avionics and cabin air, and power. Verification has been completed for multiple spacelab scenarios including SLS-2, SL-J, and SLS-3.

Mounting Systems for Plastic Glazing-Part 1-Component Level Testing

This paper presents several mounting systems or installation techniques that can be used with plastic automotive glazing. The window designs are shown to be low cost, light weight, and meet several occupant headform safety goals. The designs employ double sided foam tape, or polyurethane windshield sealant and breakaway sections. The Side impact Dummy Hybrid III headform was impacted onto prototype windows at several head velocities to record Head Injury Criteria (HIC), laceration potential, and window retention characteristics. The HIC values for all the window designs are below the 1000 value set forth in FMVSS 208.

Headform Impact Testing of Plastic Glazing Materials

The primary objective of this study was to compare the safety performance of two different plastic glazing materials to that of tempered glass in a moveable window application. A headform impact test method was used to determine if the use of plastic glazing materials offers the potential to reduce the risk of head injuries and fatalities inside impact collisions. These tests were conducted to simulate the dummy head velocity as it penetrates the side glazing area during Federal Motor Vehicle Safety Standard (FMVSS) 214 full-scale, side impact, crash testing. The two plastic glazing materials tested were an abrasion resistant (AR) coated copolymer of methyl methacrylate and N-methyl glutarimide (i.e., acrylic-imide or PMMI), and a polycarbonate (PC). Each of these window materials was evaluated in the driver's door of a Pontiac 6000 vehicle. The safety performance of these glazing materials was evaluated in each of the three categories: lacerations, head injuries due to contact, and containment. None of the materials tested resulted in lacerations which penetrated through the outer layer of chamois. This result indicates that each of the materials offered acceptable laceration characteristics. Head injury criteria (HIC) and 3 millisecond Clip values were used to assess the potential for head injuries due to contact forces. The highest HIC value measured was 262, which is much lower than the 1000 limit specified for FMVSS 208 frontal impacts. Additionally, the highest 3 ms Clip value measured was 55 g which is well below the 80 g limit specified for FMVSS 201. Therefore, the potential for head injuries due to contact is considered unlikely for each of the glazing materials. The test windows offered total containment at the following headform impact velocities: PMMI at 26 km/h (16 mph), PC at 17.5 km/h (11 mph), and tempered glass at 14 km/h (8.7 mph). The category of containment revealed the largest differentiation between these glazing materials and showed that PMMI offered total containment at much higher headform impact velocities compared to polycarbonate, followed by tempered glass.

Noise Problems Associated with Geometrically Stiffened Panels

Although geometric stiffeners (ribs, beads, dimples, etc.) may initially appear to reduce the low frequency (<300 Hz) sound radiation capacity of otherwise flat panels, when sensitivity to treatment and automobile excitation mechanisms are considered, no significant acoustic or vibration benefits are apparent. Testing does reveal that stiffeners reduce the number of low frequency resonance modes, but add on vibration treatments are unavoidable since not all of the resonance modes can practically be raised to frequencies above primary engine excitation. Further, after even relatively Light treatments are added, flat panels exhibit lower Intuition might suggest that since increased panel stiffness can effectively reduce the overall surface velocities of untreated panels, add on treatments can be reduced and current sound levels will be maintained. However, this is not the case. Although initial reductions have been made, resulting in an initial decrease in sound radiation, evidence suggests that the sound radiation from a beaded panel (treated or untreated) is seldom as low as that from a treated flat panel.

Noise and Noise Reducing Materials

Multilayer composites consist of viscoelastic polymers laminated between two metal “skins”. The polymeric core in the composite is subjected to shear, thus absorbing the incoming mechanical energy which is then dissipated as heat. This entire process acts to prevent generation of noise. These vibration damping composites are commercially more attractive because they can now be made by a continuous process in coil form rather than by the conventional, non-continuous laminating press procedure.

Structural-Acoustic Analysis for the Prediction of Vehicle Body Acoustic Sensitivities

Body acoustic sensitivity, defined as the interior sound pressure due to a unit force applied to the body, has a major influence on the powertrain and road noise of a vehicle. Body acoustic sensitivity can be predicted analytically in the design stage of a vehicle program using structural-acoustic analysis. Recognition and correction of potential problems at this stage is a cost effective approach to improving a vehicle’s NVH performance. This paper describes the structural-acoustic analysis procedure. Techniques for developing the structural and acoustic models and coupling them to form a structural-acoustic system model are discussed. An application of the procedure for prediction and improvement of body acoustic sensitivity is given for a passenger vehicle.

Small Size Devices for Accurate Acoustical Measurements of Materials and Parts Used in Automobiles

For sound absorption and sound transmission loss measurements, the existing international standards concern primarily building acoustics. The required measuring facilities are therefore very large and the corresponding surface areas of the samples are hardly comparable with the size of parts used in automobiles. Such measurements are, however, of great importance for development, comparison and optimization of sound proofing materials. Consequently, although a very large number of small size devices have been proposed which are ingenious and useful when taken separately, each one gives results which are different from the others. In this paper two devices will be presented. A small size reverberation room, which is a dimensional scale reduction 1:3 of a standardized room, is used for absorption measurements. A small emission room coupled with this small size reverberation room allows transmission loss measurements to be made. The surface area of the normal samples is 1.2 m2 for both devices and the results are comparable to those obtained according to the ISO Standards. With regard to the efforts being made to standardize methods which are well adapted to automobile acoustics, it is suggested that these two devices could be taken into consideration.

(Paint) Film Finishing in Practice

(Paint) film as an alternative to spray applied paint has received growing attention in recent years. The potential for economic and environmental advantage and quality enhancement with this technology has been reported in several technical papers (Ref. 1, 3 and 4). The actual practice of film finishing, however, has received only limited notice. Film finishes have been applied to aluminum, stainless steel, PVC, and ABS. Starting in 1982, part applications include: wheel covers, door edge guards, window surrounds, roof drip moldings, lower windshield moldings, rocker panels, body side moldings, B pillars, and A pillars. Industry awareness and acceptance of film finishing as a viable alternative to spray applied paint is increasing. The two technologies are similar in many ways, yet distinctly different in other ways. They share a common goal: To yield a durable finish, economically and with superior visual impact. This paper reviews the unique aspects of film finishing.

Development of an Experimental Modal Synthesis Method for Coupled Acoustic-Structural Systems

This paper describes an experimental modal synthesis method for determining the noise characteristics of coupled acoustic-structural systems. This method was developed to provide an essential tool for analyzing passenger compartment noise levels. With this method, it is possible to obtain the coupled acoustic-structural parameters directly from experimental measurements of noise and vibration. The resulting modal parameters provide the basis for predicting how structural modifications will affect interior noise characteristics. This paper presents the theory on which the method is based and gives examples of its application to passenger compartment noise analyses.

Application of a Generalised Frontal Crush Model of the Car Population to Pole and Narrow Object Impacts

This paper examines the deformation patterns of car fronts involved in both narrow object and offset frontal collisions and shows that the car side or sides not involved in direct crushing are pulled towards the centre of the car about a hinge point located 0.32 of the overall length to the rear of the front of the car. This corresponds with the location of the front of the car door/front bulkhead. The resulting crush profiles can be represented by simple geometric shapes. These are combined with a previously derived Specific Energy Absorption representation for the overall car population and applied to narrow object and pole impacts with car fronts. When compared with 19 staged pole impacts carried out by NHTSA high correlation is obtained and it is shown that the 95% confidence limits for calculated speed is +/- 9 km/hr.

Flexible SMC for Vertical Body Panels: Two Approaches for Success

Sheet molding compound (SMC) has long been the composite material of choice for horizontal automotive body panels. The excellent surface, dimensional stability and stiffness have made it preferred for hoods, deck lids and roofs. Softer thermoplastic and thermosetting (RIM) materials have been considered for fenders and occasionally doors, i.e., vertical body panels. However recent work has shown some performance problems with these materials and automobile companies are examining the low profile SMC alternative. For fender applications increased flexibility over current horizontal body panel materials is desirable. Obtaining this flexibility can be readily achieved but usually at the expense of surface smoothness. This paper reports on work done to achieve a Class A flexible SMC system for compression molding. Markedly greater flexibility of molded parts has been achieved by new combinations of low profile additive and unsaturated polyester resin technology. Discussions of surface and flexibility testing will be presented.

Polymeric Reflective Materials: The Future of Body Ornamentation and Lighting

Polymeric Reflective Materials (PRM) offer the automotive designer a unique new material and processing technology for vehicle ornamentation and lighting. PRM is a highly reflective multi-layer thermoplastic extruded sheet containing no metallization or surface coatings to create it's reflective appearance. PRM's ability to “transflect” light is a very unique characteristic. Transflection is the ability to simultaneously transmit and reflect light. PRM enables the integration of lighting components and exterior ornamentation to create uninterrupted exterior styling lines. PRM allows lighting components to disappear. Targeted applications include rear lighting lenses, illuminated body trim, emblems, door edge guards, safety lights, etc. Additionally, unique visual effects are created by front and second surface decorating. PRM also offers many interior styling options. The design concept is to have components appear bright metallic (silver, gold, copper, etc) and change appearance and or/color when back illuminated. PRM is formed and fabricated by conventional thermoforming methods. Conventional methods are utilized to trim formed PRM parts.

A Single-Supply, Monolithic, MIL-STD-1553 Transceiver Implemented in BiCMOS Wafer Fabrication Technology

An integrated circuit has been designed for use as a single supply, MIL-STD-1553 transceiver using BiCMOS technology. Use of the BiCMOS fabrication process has advantages over both Bipolar and CMOS technologies. These advantages include: reduced standby current drain, increased flexibility in mating the transceiver to various remote terminals, increased control over output amplitude and rise/fall times, easier methods for adjusting filter response and residual voltage, and reduced chip size (over a CMOS transceiver). Development of this monolithic transceiver opens the door to future advances in remote terminal design. By combining the current driving capacity of Bipolar with the digital design capability of CMOS, the next probable step in the progression of MIL-STD-1553 technology would be a fully monolithic remote terminal. This device would combine a transceiver with the encoder/decoder and protocol logic on a single semiconductor device.

DNC/CNC Riveting Cells Applied in the International Aircraft Industry

During the past decade, the number of implemented DNC/CNC Riveting and Assembly Systems has substantially increased and new applications have been introduced into areas where only manual or semi-automatic assembly was once considered. The main reason for developing these systems was the increasing demand for a better level of quality and higher production rates. This paper describes new upper tooling conceived as modular building blocks used on C-frame riveting machines. In addition, applications of C-frame riveting machines for the automatic assembly of pressure bulkheads and freight room-/passenger doors are discussed. Other applications described include the automatic floor grid assembly of large commercial aircraft.

Considerations for Plastic Abrasion Resistant Coated Windows for the Automotive Industry

With the advent of today's abrasion resistance (AR) coating and plastic technologies, an alternative to glass glazing is now feasible. Automotive use of earlier forms of these products have pushed the research and development efforts of material suppliers and processors to the present state. Where this technology has been, how it has progressed, and what considerations are required for its utilization today will be discussed. The object of this paper is to define the design and processing characteristics required for the successful application of AR coated plastic, as a glazing material.

Development of a Practical DSP Car Audio System

Digital signal processors (DSPs) are being used widely for sound field reproduction. However, it is difficult to apply a DSP to a car audio system because of the complicated acoustic characteristics of the passenger compartment. The authors have developed a new car audio system which employs special DSP software and a new speaker layout to provide excellent presence. The DSP has five output channels to generate stereophonic reflection from the front and rear speakers. The DSP software is programmed for each individual car model. A center speaker and A-pillar tweeters are used to produce a natural sound field in front through effective utilization of reflection from the windshield. This system is featured in 1992 Nissan models.

Cold Start Improvement by use of Latent Heat Stores

Engine and cabin heating problems associated with cold starts at subzero conditions are greatly reduced by use of a Heat Battery. This is a latent heat store, collecting waste heat from the engine and storing it by use of efficient heat insulation. On the next cold start the heat is released with high initial power. The performance increases with colder environment conditions. Startability of the engine and the warm-up performance are improved. Emissions of hydrocarbons and carbonmonoxide are reduced up to 80 % in the CVS test at -7°C (20°F) and Diesel noise is lowered. The windshield is cleared of ice and frost and kept free of mist. Passenger comfort improves since hot air flows into the cabin within seconds after the Heat Battery is engaged.

Reconnaissance Capable F/A-18D Optical and Infrared Window Antifog Systems

Aircraft modifications have been developed to make F/A-18D Hornets capable of being converted to a reconnaissance configuration which includes both optical and infrared sensors. A major design challenge was to prevent fog formation on the two exterior moldline windows used for viewing by these sensors. Antifogging was required during a rapid 7620 m/min (25,000 ft/min) descent into humid atmospheric conditions following a sustained cold soak at altitude. This paper describes the design development and laboratory verification testing of the two unique antifog systems selected to meet this requirement.

Enhanced Heat Transfer by a Spiral Spring Augmentive Device Inside a Round Tube

The use of augmentive devices in round tubes to promote heat transfer has been known to the industry for some time. Early work has shown that the improvement in heat transfer in a round tube is considerably greater with an augmentive device when in the heating mode than in the cooling mode. As a result, the bulk of the effort, thus far, appears to be in the heating mode. This work is set to prove that the augmentive devices are as efficient in the cooling mode as in the heating mode. This work also opens the doors to many applications where space and cooling equipment size are a factors to be considered during the design of systems. This study utilizes a spiral spring augmentive device in four wire diameters and in four turns per inch for each wire diameter in a nominal 0.375 diameter copper tube. The coil diameter of the augmentive device was sized to fit inside the tube with a minimum clearance.

The Effects of Instrument Panel Top Color and Windshield Angle on Veiling Glare

This Paper summarizes the results of research on the causes of windshield veiling glare in automotive vehicles. A special test apparatus was and built to simulate real-world windshield glare conditions. Four subjects were required to perform identification tasks under various levels of veiling glare. Error frequency and discomfort rating were used as the measurement of glare level. Results show the influence windshield glare from such parameters as solar brightness, solar position, windshield angle and instrument panel top color. Instrument panel color was evaluated using the Munsell attributes of Hue, Value, and Chroma.

A System Approach to Safe Winter Driving Considerations: The Visual System

A systems approach is used to analyze the problem of providing optimum visual capabilities to deal with the demands required for safe driving in cold weather. Using a systems analysis approach, the problem is divided into its constituent parts (e.g. road conditions, vehicle features and design, the human components, etc.) and then these components, as they pertained to the defined visual system, are addressed.. Under temperate driving conditions, visual acuity and field of view are two of the most important considerations for safe driving. While these still remain important during winter driving conditions, windshield clarity and the problems associated with it, becomes extremely important. These three requirements have many related characteristics that may be overlooked when a systems approach is not used.

Vertical Body Panels: Flexible Class A Surface Composites Via Compression or Injection Molding

Low Profile Class A sheet molding compound (SMC) is recognized as the composite material of choice for horizontal automotive body panels. The excellent surface, dimensional stability, stiffness and coefficient of thermal expansion have made it preferred for hoods, deck lids and roofs. softer thermoplastic and thermosetting (RIM) materials have been more considered for fenders and occasionally doors. recent studies have shown performance problems with these materials and SMC composites are being considered as an alternative. Increased flexibility over standard rigidity SMC is considered desirable for vertical body panels, particularly fenders. This flexibility can be achieved but normally at a major price in surface smoothness. This paper reports on research and development work done to achieve Class A surface flexible SMC/BMC composites that can be either compression or injection molded. these advancements have been made by a combination of shrinkage control agent (low profile additive) chemistry, unsaturated polyester structure, fiber wetting agent and fiberglass size technology. A comparison is made of surface characteristics, flexibility and physical properties which can be obtained via these two processing/molding techniques.

Improvements and Applications of Permanent Magnet Materials in Automotive Sensors

Advancement of automotive electronic technology is leading to a greater use of permanent magnet materials. New vehicle specifications demand sensors and D.C. motors to be lighter and more efficient. Magnet manufacturers are developing materials and processes to meet these needs, both for the present and the future. Permanent magnets today are used in a wide range of industrial, domestic, automotive and aerospace applications. Their special, technological importance derives from their ability to act contactlessly on ferromagnetic material, either by attraction or repulsion, and to provide a permanent magnetic flux with no energy input and, hence, at no operating cost. The current usage of permanent magnets in domestic applications averages 50 per household in the United States, as illustrated in Figure 1. Perhaps the most surprising range of permanent magnet uses are the numerous applications in a modern passenger vehicle. These applications include an array of D.C. electric motors such as the starter, heater and air conditioner blower, windshield wiper, window lift, door lock and fuel pump motors. A fully equipped car can have more than 30 D.C. electric motors. Other uses include actuators, gauges and sensors, as shown in Figure 2. In all these examples, higher performance magnetic materials may afford the advantages of increased operating efficiency and reduction in size and weight. The continuing improvement in magnetic materials together with advances in power and integrated electronics has seen the development of a wide range of devices in which field coil windings are replaced by permanent magnets. These developments have also led to a dramatic increase in the use of permanent magnets in automotive sensor applications.

Automotive Testing Requirements in the Design of a Reverberation Chamber

The purpose of this paper is to identify various concerns that need to be evaluated prior to the design and construction of a reverberation chamber, such that the chamber can be used for various automotive related acoustical measurements. Some of the concerns involve issues such as room shape and size, the degree of sound and vibration isolation required, the use of conventional building materials versus traditional massive construction, construction cost, and the performance requirements for the test noise generation system. Various uses of a reverberation chamber include random incidence sound absorption measurements, small sample sound transmission loss measurements, vehicle insertion loss tests, dash panel, door, and other “buck” evaluation tests, and sound power level measurements of small automotive components and devices. These uses have differing and in some cases conflicting requirements that compete in the selection of room design parameters. The paper discusses these issues including the requirements for sound level generation in the chamber for proper measurements. The paper also provides case studies on the use of reverberation chambers for automotive applications.

Acoustical Performance Testing of Automotive Weatherseals

Advances in vehicle noise control are leading the automotive industry to place increasing emphasis on weatherseals to block exterior noise. As a result, properly evaluating the acoustical performance of automotive weatherseals is of increasing importance. There is no current specific standard for this testing. Rather, there has been reliance on adaptations of SAE Standard 51400 “Laboratory Measurement of the Airborne Sound Barrier Performance of Automotive Materials and Assemblies” by testing laboratories. However, the 51400 standard addresses testing of flatstock materials and does not readily lend application to pre-formed parts such as weatherseals. For this reason, adaptation of the standard can vary significantly from facility to facility and manufacturer to manufacturer. These differences can be significant and can render comparisons between test results on competing materials very difficult. This paper explores some of the limitations of using SAE J1400 to evaluate weatherseal performances and the likely impact of these limitations on test results. It also offers some considerations on developing a test procedure for an appropriate standard for evaluating weatherseals.

Automotive Squeak and Rattle Prevention

Recent advances in automotive sound quality have reduced the general level of noise in the passenger compartment and focused more attention on irritating noises. Traditional methods of prevention and elimination of irritating noises such as squeaks and rattles are no longer sufficient to develop acceptable products in shortened product development cycles. Basic causes, design rules for prevention, and evaluation techniques using integrated digital data acquisition, laboratory simulation, acoustic and modal analysis techniques have been successfully developed to push the prevention process upstream in the development cycle.

Design of Automotive Audio Systems Using the Acoustic Transfer Function Measurement

The small, irregular volume of the typical automotive cabin can induce large, unpredictable variations in the low frequency response (<200 Hz) of woofers in the audio system. Acoustic transfer function measurements of these effects, made using a reciprocity technique, show these variations at the listener's position. The response of a subwoofer design at any position in the vehicle can be predicted and optimized through computer aided convolution of the woofer response and the acoustic transfer function. A commercially available loudspeaker acoustic simulator, SPEAK, was used for woofer system design and simulation in an automobile.

Engineering, Optimization, and Tuning of vehicle interior Sound Absorption and Other mechanisms for Sound Reduction

This paper treats the engineering, optimization and tuning of vehicle sound absorption with emphasis on headliners. It covers the methodology of measuring sound. The mechanisms for sound reduction damping are discussed. The report compares the acoustical performance of worldwide headliner constructions at different frequencies and leaves it up to the reader to make his/her own evaluation. The Authors discuss means to enhance and optimize and tune headliners to increase the acoustic functionality of the parts. The paper also shows the relative acoustic performance of interior trim parts. Future trends and methodology are explored along with the European trend to eliminate roof bows and the headliner being robotically adhered to the roof to improve acoustics, structural effectiveness and lower cost.

Vehicle Drive Line Dynamic Behaviour Simulation

A mathematical model was built up and a computer programme was developped in order to simulate the drive line of a vehicle. Particular attention was given to the possibility to incorporate non linearities such as teeth clearence and torsional stiffness of the clutch plate. With the model it is possible to study rattling and hammering of the gearbox and in particular the influence of the clutch on it. Also the influence of a vibration absorber on resonance frequencies is investigated. Due to a extrapolation of the programme, we are also able to analyse the interaction between the torsional stiffness of the driveline and the axle vibration on his suspension.

The Application of Bonded Aluminum Sandwich Construction Technology to Achieve a Lightweight, Low Cost Automotive Structure

Bonded Aluminum Sandwich Construction Technology offers a new approach for automotive manufacturers to rapidly develop low volume niche products that achieve world class results for weight, cost, styling and surface finish with minimal tooling investment. Using sandwich panel construction in the development of their new ultra lightweight sleeper, Western Star Trucks was able to reduce the product weight by 50%, manufacturing costs by 25%, and tooling and development cost by 75%, while significantly reducing development time. In less than one year the company was able to deliver a new family of Star Light Sleepers that replaced a conventional stamped steel body-in-white structure with the same basic body shape but with improved styling detail and surface finish. Additional benefits encountered included increased ease of assembly and interior finishing, and improved reparability and noise and thermal attenuation.

Aeroacoustics of an Automobile A-Pillar Rain Gutter: Computational and Experimental Study

Noise due to the flow over an automobile A-pillar rain gutter in isolation was computed using a two step procedure. Initially the flow solution was obtained by solving the Reynolds Averaged Navier Stokes (RANS) equations. Acoustical Sources were extracted from the flow solution and propagated to the far-field using the Lighthill-Curle equation. Experiments were conducted to evaluate the computations. Compared results include steady pressures, time dependent pressures, and sound intensity levels. Computed results and experimental data were reduced in a similar way to ensure a one to one comparison. Computed results are in good agreement with the experimental values. A-weighted noise levels are predicted reasonably well.

Booming Noise Analysis Method Based On Acoustic Excitation Test

A method for analyzing and decreasing booming noise in the cabin of a minivan using acoustic excitation tests has been developed. To ensure a pleasant ride for passengers of minivans equipped with four-cylinder engines, decreasing cabin noise from secondary components of engine revolution has become a priority. “Booming noise” in the cabin originates from engine vibration that passes through engine mounts to shake the body structure and body panels. To decrease the level of sound pressure resulting from this shaking, one effective approach is to reduce the level of the mechanical-acoustical transfer function (MATF) in the interval from engine mounts to passengers' ears. This paper reports on a specific method for reducing the level of MATF. In this method, a speaker is positioned near a passenger's ear to measure the vibration-response level at the points where engine mounts are installed when exciting the body structure, and the level is reduced by modifying the body structure. This method makes use of the relationship between MATF and vibration response during acoustic excitation, which can be considered equivalent according to the reciprocity principle. The following conclusions were reached when applying this method to decreasing 60- to 120-Hz booming noise in minivans that mount the engine under the driver's seat. The pattern of vibration distribution measured when exciting body structure by a shaker is generally different from that measured by acoustic excitation, and the proposed method that modifies body structure to suppress the latter vibration can improve MATF levels in a relatively short time. In other words, when exciting body structure by a shaker or when running the vehicle, the vibration components of body structure that excite the cabin resonance mode and generate booming noise are normally hidden by vibration components that do not result in sound.

Four Legs in the Morning: Issues in Crew-Quarter Design for Long-Duration Space Facilities

In designing habitats for long-duration space missions, one of the primary issues to address is that of sleep spaces, commonly known as Crew Quarters. While ergonomic design plays a major role in short-duration crew quarters (CQ) design, longer term missions must take into account the significant effect which environmental factors have on crew productivity; to that end, the establishment of private space for each individual crew member, as well as a range of semiprivate work and rest areas represents a significant departure from established norms in space habitat design. Both for proposed planetary habitats and microgravity habitats, various systems must be studied to enhance the wellbeing of the crewmembers. Improved lighting, color, and acoustic environments as well as the introduction of diurnal simulation systems, virtual windows, flexible partitions and other potential innovations are being investigated by the Space Habitation Design Group as means of developing efficient, high-acceptability crew accommodations.

Everyday Noise - All Day

In the Lunar-Mars Life Support Test Project chamber, crewmembers collected various sound level measures starting with the entry day ceremonies and ending with the welcome home celebrations. Crewmembers recorded sample decibel(A) levels in the 80s and 70s in the mechanical area; 70s and 60s in the common living and work areas; and 50s and 40s in the individual crew quarters. Medical personnel evaluated crewmembers for threshold hearing shifts comparing audiometry readings before and after the chamber experience. The discussion relates the chamber findings to the operational requirements for space stations and planetary habitation, as well as for long duration exposures on Earth.

Aeroacoustic Testing Improvements at Pininfarina

Aeroacoustics is playing an increasing role in the development of new passenger cars. However, most existing wind tunnels, with few recent exceptions, have been designed and built with little or no attention to their aeroacoustic aspects. Building new wind tunnels with excellent low noise levels is technically feasible today, however it is not often justifiable from an economic standpoint. In the case of the Pininfarina wind tunnel, built in 1972 without any specific noise target, a decision was taken in 1984 to progressively upgrade the facility and the acoustic measuring techniques. A target of reaching a background noise level low enough to allow satisfactory acoustic development work on new cars, with the contemporary use of more modern measuring techniques, was established. This decision implicitly assumed that, to do this development work, it is not necessary to reach the very low noise levels of a pure acoustic wind tunnel. The paper reports a short description of the main modifications made to the facility, in the years 1985-90, and the main results obtained. Then, it describes some of the new measuring techniques which have been set up in the meantime. They are optimized so as to be as efficient as possible in the presence of the background noise. This noise has a relatively low level and a favorable spectrum when compared with other aerodynamic wind tunnels, but this noise still remains worse than that of the acoustic wind tunnels. In order to further improve the existing situation, a new three-year research program has been recently started (mid 1992). Its main aim is to improve the capability of detecting the noise sources on the outer surfaces of cars. To do that, new measuring techniques are in course of development and testing. At the same time, further modifications to the facility are going to be carried out, mainly to its fan-drive system, to reduce the background noise level. An overview of this new research program is reported in the second part of the paper, together with some examples of the latest experimental results.

Measurement and Prediction of the Sound Transmission Loss of Automotive Glazing Materials

The transmission of sound through automotive glazing materials was investigated. The sound transmission loss in one-third octave bands of several different automobile windows was measured at a testing laboratory. The materials tested included monolithic (single-layer) glass, monolithic polycarbonate, and a double glazing with an air gap in between the two panes. The experimental data are given in the paper. Subsequently, a computer spreadsheet program was written and developed to predict the sound transmission loss of single-layer glazing materials, using empirical equations found in the literature. The predicted sound transmission loss values showed good agreement with the experimental values. The sound transmission loss spreadsheet is a useful, easy-to-use tool to predict the acoustic performance of automobile window glazing materials.

Multilayer Laminated Composites for Noise and Thermal Control - PRE FINISH METALS

Continuous developments in car design and customer attention to performance and comfort have created necessities for improvements in external and internal noise reduction in cars, trucks and busses and thermal control around engine and exhaust areas. Solutions to these “challenges” are usually combinations of novel designs and selection of more efficient engineering materials. The authors describe the development of laminated composites consisting of outer metal “skins” with a specially selected core material between them. Depending on the noise damping and/or thermal insulation properties required by the application, the core materials may be viscoelastic polymers or inorganic materials.. As the result of this development, “families” of different materials for such applications are presented with the description of material properties and potential uses. These material systems include composites for noise reduction of parts in engine compartment, body parts, brakes, and materials for thermal control in under-the-hood, exhaust, and catalytic converter applications.

In-Car Early Reflection Studies Using In-the-Ear Microphone Techniques

After prototyping numerous sound systems for automobiles, it is often frustrating for the design engineer to gather a number of listeners and each turns out to have their own perception of the system performance. Some people are sensitive to localization problems in the car yet are unaware of reflection induced frequency response problems. The converse holds true for other listeners that notice small anomalies in frequency but are oblivious to localization difficulties. A trained listener can often balance the frequency and imaging issues though by tilting their head or mentally biasing the acoustical data. The reasons for these differences in listeners is often due to the pinna, which is the visible part of the outer ear. In-The-Ear™ microphones, recently developed by Etymotic Research [1], are placed in the ear canals of several listeners to measure these influences in hope of understanding why these contrasting opinions exist.

Experimental Investigaton of Radio Antenna Wind Noise

Recent advances in the field of vehicle noise control have subjected the automobile to the “drained swamp syndrome”. Quieter engines, powertrains and bodies, combined with passive sound treatments for the interior have unearthed the stumps; radio antenna wind noise is one of them. This has prompted various innovative designs and redesigns for radio antennas that have been employed by major manufacturers in recent vehicles. This paper aims to determine the optimal antenna design through experimental testing both on the road and in the laboratory.

Engine Sound Quality in Sub-Compact Economy Vehicles: A Comparative Case Study

A comparative study was undertaken to investigate engine noise in sub-compact vehicles under typical highway operating conditions. Baseline acoustical testing was performed. Typical sound quality metrics indicated that passenger cabin noise levels and sound quality were similar among all vehicles tested. However, poorer subjective sound quality in a vehicle equipped with a 3-speed automatic transmission was related to a higher degree of perceived periodicity than in other models. Further study of the 3-speed vehicle indicated that installing a 4-speed transmission would reduce noise more effectively than any substantial changes to the vehicle structure or engine mounting system. Damping or barrier treatments applied to the firewall or toe pan did not provide significant benefit.

Design and Test of Voice Interfaces in Cars

Voice interfaces are of much interest for car designers: they are a safe way to operate various devices. However car compartments are very hostile environments for voice capture and emission because road noise is very loud. For every new car much time must be spent on their optimization which involves tools for quality evaluation. Comparing configurations is not practical while driving. A simple model of voice interfaces based on impulse responses makes reliable tests much easier to implement. This paper describes its practical application and shows a few objective results.

Effects of On-Road Turbulence on Automotive Wind Noise: Comparing Wind-Tunnel and On-Road Tests

For high-speed driving conditions, the air flow around a car creates wind noise that is transmitted into the cabin, which can dominate other noises. If an atmospheric wind is present, it will create a turbulent cross wind, which not only changes the air flow velocity and direction as experienced by the vehicle, but leads to continuously varying wind noise, as heard inside the car. The purpose of this paper is to look at how the on-road wind environment affects wind noise, and to evaluate the need to simulate real on-road conditions such as fluctuating yaw angles and velocities in vehicle wind tunnels.

Assessment of Air Bag Module Durability Test Specifications Using CAE Techniques

Several air bag module vibration testing issues are identified. Eight OEM air bag module vibration test specifications are compared in terms of predicted fatigue lives using computer simulation. The specifications differ significantly in the type of loading (sine sweep, fixed sine and random), frequency range, and test duration. The comparison results indicate large variation in the relative severity of specifications based on the computed fatigue lives. This variation indicates that a more standardized approach for deriving representative vibration test specifications is desirable. The unrepresentative specifications can lead to overdesigned components, diminishing the value of the air bag system. Experimental results used to validate the analytical predictions are presented along with the simulation results. A computer program developed to perform the fatigue life calculations for both sine sweep and random vibrations is also described. Several suggestions for developing representative specifications are provided.

Importance of Sealants for Interior Noise Control of Automobiles

Sealant materials are used in todays automobiles for many applications such as, sealing of body seams, sealing access holes and the filling of hollow cavities. The primary reasons for these applications are to prevent corrosion, prevent water intrusion, and to reduce the noise level in the passenger compartment. However, the noise control capabilities of sealant materials have not been explored until recently. This paper discusses the requirements that a noise control material must possess, and reviews how a sealant material can fulfil these requirements. Properly designed sealant materials can possess sound transmission loss (barrier) properties, vibration damping properties over a given frequency and temperature range of interest, and often sound absorption properties with proper formulation. This paper provides case studies to substantiate the acoustical capabilities of sealant materials.

Automotive Rollover Angular Rate Sensors and Evaluation

This paper presents a test methodology for evaluating angular rate sensors used for detecting vehicle rollover. The key electrical parameters over temperature are tested with a rate table. Immunity to linear accelerations is evaluated at room temperature with a vibration table and a thruster. The vibration test provides mechanical resonance information and rough road performance, while the thruster test provides g-sensitivity parameters under severe impact conditions such as with vehicle frontal and side impact events. The vehicle level evaluation includes severe vehicle maneuvers, rough road and gravel road tests, as well as full-scale vehicle rollover tests.

Vehicle Passenger Door Hinge Systems

The scope of this SAE Recommended Practice is to establish recommended uniform test procedures and minimum static load requirements for vehicle passenger door hinge systems. Tests are described that can be conducted on test fixtures and equipment in laboratory test facilities. The test procedures and minimum performance requirements outlined in this recommended practice are based on currently available engineering data. It is intended that all portions of the recommended practice be periodically reviewed and revised as additional knowledge regarding vehicle hinge system performance under impact conditions is developed.

Application of Formable and Self-Skinning Polyurethane Foams in Headliners

The initial function of headliners in automobiles was to conceal the rough appearance of the exposed roof construction. As the roof construction evolved towards solid metal, the requirements for headliners grew to include acoustic and styling properties. Today, fiberglass-based headliners have the major share of the North American market in high and mid-line vehicles. However, there is a recent trend to find substitutes for fiberglass headliners because of their skin irritation effects on assembly workers. Headliners based on formable and self-skinning polyurethane foam have gained wide acceptance in Europe as an alternative to fiberglass. This paper discusses the different PUR processes involved and the characteristics of the finished headliners produced with these PUR foams.

Simple, Passive, Non-Contact Class A Multiplexing Method Using Programmable Surface Acoustic Wave Devices

This paper describes a novel technique for class A sensor-to-module multiplexing using surface acoustic wave (SAW) technology. This technique converts information on the status of N switches to a series of N pulses in the time domain. The basic enabling technology is a programmable SAW reflector, which may be programmed to either a nonreflecting or partially reflecting state by closing or opening a switch connected to the reflector. The SAW device consists of a transducer and N programmable reflectors printed on a piezoelectric substrate such as lithium niobate. To read the status of the switches, an electronic module sends an interrogating rf pulse to the transducer. At a series of later times determined by the spacing of the reflectors from the transducer and the SAW velocity, return pulses are generated whose amplitudes are determined by the corresponding switch settings. Coupling between the electronic module and SAW device utilizes a pair of coupling coils. This allows the status of switches on a rotating or moving object such as a steering wheel, tire, or door, to be read without making any electrical contact to the moving object. Only the switches, the SAW device, and a coil, all passive components, need to mounted on the moving object. A system to read 15 switches on a steering hub has been developed utilizing a simple SAW device and low-cost electronics, and it is straightforward to extend the system to a higher number of switches.

Use of Continuously Annealed Bake Hardenable Steels for Automobile Outer Panels

The automotive industry's ongoing effort to improve quality and reduce weight without added cost has led to the investigation of many medium strength steels. This study presents a comparison of continuously annealed Bake Hardenable Steels (BHS) with current DQSK production materials for outer panel applications. While all steels exhibit strength increases from work hardening during forming, BHS has a unique and ideal characteristic which produces an increase in yield strength due to strain aging during the paint baking process at the automotive assembly plants. This results in an increase in dent resistance. BHS is a desirable material for relatively flat outer panels which often receive only small strains during forming such as in doors, hoods and decklids. Improved durability against dents, dings, and palm printing are obtained in the BHS parts. Similarly, quality improvements are realized in the stamping and assembly plants by a decrease in handling and transit damage.

A Multilayer Membrane-Tension Automotive Door-Barrier System

An alternative device based on the membrane-tension principle was developed to improve the resistance of vehicle doors to side impact. The device is comprised of several layers of sheets. The outermost layer is essentially flat and the other layers are corrugated, each with the same pitch but with a successively greater depth. The ends of each layer are attached to tabs which are connected to the door frame in a manner suitable for developing the required forces. In this concept, the side impact pushes inward on the outer sheet and causes it to develop membrane tension because its axial movement is restrained at its ends. As the inward intrusion increases, the outer sheet stretches inelastically and eventually ruptures. This action continues as successive sheet layers are stretched to rupture. The computer program, DOOR1, was developed to aid in designing the device to suit various geometries and packaging criteria. Tests were conducted on prototype specimens and compared to a companion test of an existing system. The tests indicated that the new door barrier device acting alone can deform up to 18 inches and reach a maximum load of at least 11,000 pounds in a typical three-layer, 46-1/2-inch span configuration. Details can be selected so that the load-deformation curve can be engineered to provide a desired shape. Because it appears that the new device could potentially improve crash resistance, full-scale tests on a vehicle are planned.

Characteristics of Box-Annealed Bake-Hardenable Steels

Bake-hardenable steel optimizes the combination of higher formability (low strength and high ductility) needed for part formation and higher final strength needed for dent resistance in the finished part. In outer panel design, it is important to understand the bake-hardening mechanism and its relationship to strain states in the part, bake temperatures and time. Bake-hardening steel exhibits carbon strain-aging that significantly increases the material's strength after part formation. The aging mechanism is created in box-anneal sheet product by the control of annealing parameters and heat composition. Property data from bake-hardenable material currently being used on a door outer application is discussed. Two different aging studies show the relationships between bake hardenability and the variables of strain, baking temperature and baking time. A third study demonsrates that, once strain is induced, strain-age hardening begins to occur at room temperature.

Soft and Light Door Trim by Using Double Slushed Skin and Glass Mat Reinforced Rigid Polyurethane Foam Core

As for recent market needs, there is an increasing demand for the total coordination of the vehicles interior trims, the enhancement of adaptability for freer designs, soft touch and weight reduction. In order to meet these demands, we have developed a door trim reflecting this new concept. This door trim is manufactured by foaming rigid polyurethane foam as the core material after the double slush skin (1st layer: PVC, 2nd layer: PVC foam) and the glass mat are set together in the foaming mold. Employment of double slushed skin allows an improvement in flexibility of design, softer materials to be manufactured and further coordination of color, gloss and grain pattern with those of instrument pad. In addition, we have succeeded in reducing the weight by using glass mat reinforced rigid polyurethane foam. Since the center ornament fabric is formed together with the skin, the look at the joint section of the fabric and skin has been improved remarkably compared to conventional products. We also succeeded in reducing the number of processes by abolishing the ornament assembly process and by improvement in the treatment of periphery and terminal of parts.

Turnkey Processes for Window Encapsulation

As window encapsulation technology advances, the requirement for process improvements to decrease cycle time, improve part quantity, and to minimize labor requirements becomes very important to the manufacturers. Traditional module systems have advanced to include closed-loop control metering units; fast acting, reliable presses; and SPC data collection systems. Turnkey automatic systems include robotic load/unloading, centering station, automatic/semi-automatic priming station, and robotic IMC/mold release. The demands to reduce overall costs has led manufacturers to consider several alternatives that prove best for their application. This paper is to list and expand on these alternative solutions.