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Design of Elastomeric Vibration Isolation Mounting Systems for Internal Combustion Engines | The Internal Combustion engine, by nature a dynamic vibration source, requires a properly designed flexible mounting system to isolate those disturbing vibrations. To do this it is necessary to consider all six degrees of freedom of the engine and to use the computer to determine vibratory outputs for given inputs. An example of such a computer program is given. In addition, the design of a mount system requires consideration of static and dynamic force resistance and reduction, motion limitation, environmental resistance and service life requirements. Elastomeric mounts can provide substantial noise reduction but due to the complexity of the noise problem, the prediction of the actual amount of reduction is more of an art than a science. High frequency problems caused by ?쐓tanding waves??in an elastomeric mount are very much less likely to occur than those due to structural resonances. Examples of noise reductions due to the addition of elastomer mounts, on some actual vehicles, are given. |
Safety Performance of Securiflex Windshield | An improved windshield with a special, thin, plastic inner surface attached to the inner surface of a three layer windshield similar to those used in the United States minimizes lacerations from occupant impact to the windshield during a collision. The plastic coats the sharp edges of the broken glass preventing or minimizing laceration. It was evaluated by comparing its laceration performance with that of a standard windshield in simulated barrier crashes at velocities up to 65 km/h. No lacerations resulted from impact to the Securiflex windshield at Barrier Equivalent Velocities up to 65 km/h. Substantial laceration resulted at velocities above 20 km/h with the standard windshield. It is concluded that the Securiflex windshield essentially eliminates lacerations in the particular vehicle involved at velocities up to at least 65 km/h. |
Less Noise From Diesel Trucks | An indepth study to reduce noise produced by a typical highway diesel truck is being conducted to determine levels and costs attainable by practical means. Truck noise reduction involves isolating several individual noise sources, that is, fan, exhaust, engine-radiated, intake system, and others, and developing means to reduce each. Tire noise and major engine revisions are not considered in this project. Goals of 78 dB(A) (per SAE J366a) without engine enclosure and 75 dB(A) with engine enclosure are believed possible on the vehicle configuration being studied. This project is sponsored by the U.S. Department of Transportation Office of Noise Abatement, and industry. |
Propulsion Integration for a Hybrid Propulsive-Lift System | In a discussion of STOL vehicles with conventional high-lift devices, the need for efficient power-augmented lift systems is presented and the implications of quiet operation are noted. The underlying philosophy of a promising hybrid lift system with major interactions between aerodynamic, thermodynamic, acoustic, and configuration design technologies is derived. The technique by which engine and airframe-related characteristics for this application may be matched in an optimum manner is described and illustrated by describing the features of a particular short-haul commercial STOL vehicle. |
Human Engineering Applied to the Design and Grouping of Electrical Controls in the Motor Vehicle | A study has been made of motor vehicle driver environment in order to determine the most desirable design features and the optimum grouping of electrical controls conducive with minimum conscious thought and physical effort in location and operation under any given set of conditions. Consideration is given to the psychological aspects of control operating noise level and action ?쐄eel,??to styling and standardization of layout with the ultimate objective of driver fatigue reduction, and to a worthwhile contribution in road safety improvement. |
Sound Attenuation in Operator Enclosures | This paper outlines parameters for the design of operator's enclosures (cabs), with special reference to noise control. Specific suggestions for the solution of noise pollution include shock mounting of the cab, plugging all holes through which noise can enter, attenuating large sheet metal areas by damping, effectively using large amounts of glass, diverting the exhaust outlet away from the cab, providing a fan shroud, not mounting sound generating components to enclosure walls. Such steps should reduce the sound level by 15-20 dB, but will add 12-15% to the overall cost of the enclosure. |
Interior Window Fogging - An Analysis of the Parameters Involved * | Many factors are directly related to the occurrence of window fogging and flash fogging. The pertinent variables affecting the problem are identified and discussed. In simple terms, fogging is dependent upon the difference between the dew point temperature of the interior environment and the glass surface temperature. Several dew point and glass temperature curves have been computed which typify various operating conditions. Alternatives that will help to eliminate fogging are discussed. |
New Methods of Reducing Noise in External Gear Pumps | The noise from external gear pumps has been significantly reduced by a new design which consists of two sets of gears, half the width of a standard gear, and offset about 1/2 pitch. The new pump makes use of a housing which is externally basically the same as a standard pump. This paper presents test stand and field measurements of the pump. |
Advanced Olympus for Next Generation Supersonic Transport Aircraft | The paper summarises the background studies which have led to the proposal for an advanced Olympus engine, with mechanical noise suppression, to power the next generation supersonic transport aircraft. The recent international collaborative test programme on real engine scale ejector suppressors is described and reference is made to other Rolls-Royce experimental work at model scale. The envisaged changes to the design of the in-service Concorde engine are outlined and some installation aspects are discussed. It is emphasised that detailed refinement of the engine cycle must depend on the result of aircraft/engine integration and optimisation studies. |
Bulldozer Noise Control | Bulldozer noise is the most serious noise problem for surface miners today. Not only are bulldozers the most common type of mobile equipment, but the majority of their operators are also exposed to more noise than current federal regulations allow. In 1977, the Bureau of Mines responded to this problem by developing retrofit noise control treatments which reduce the noise that reaches the operator. These treatments were specifically designed to be readily installed in the field at low cost. In 1978, these treatments were installed on two Caterpillar D9G?셲 in surface coal mines to demonstrate the noise reduction that can be achieved under actual production conditions. This paper presents the results of the field demonstrations. |
Side Impact Sled and Padding Development | IN A ONE YEAR LABORATORY STUDY, a side impact sled was designed, built, and validated. Using the sled and a newer generation of side impact dummy, a number of energy-absorbing materials were tested and superior materials identified. Initially this study concentrated on the crash test data for a number of V.W. Rabbits crashed in a previously completed study. The crashed vehicles were obtained, and interior crush tests were performed with a specially designed body form. This was done to determine how the effective stiffness (as seen by the occupant of the struck vehicle) of the interior door increases as the bullet vehicle presses against the interior door trim from the opposite side. An acceleration-type sled buck was then designed and built with an ?쐇nterior door??mounted to mimic the interior stiffness determined from the crush tests. The sled was dynamically tested with a Haversine sled pulse similar to the door crash pulse. The sled was validated by reproducing the crash environment of a car-to-car collision. The criteria considered for matching the two were: (1) acceleration-time curve of the interior door, (2) the velocity-time curve of the interior door, (3) kinematics of the Part 572 surrogate, and (4) accelerations on the surrogate. |
Evaluation of Pelvic Fracture Tolerance in Side Impact | Pelvic fracture is a typical lesion sustained by the occupant of a vehicle involved in a lateral impact collision who is seated on the impact side. If this fracture is generally not severe by itself, it is nevertheless often associated with severe abdominal lesions. Study of injury mechanisms in lateral impact collisions shows that there are two ways of ensuring a better protection of the occupant in this type of accident: first by preventing intrusion so that the contact velocity ?쐎ccupant/inner door??is decreased, secondly by absorbing the shock of the occupant against the inner door, especially at pelvis and thorax levels. It is necessary to have a good knowledge of human tolerance to fracture of the considered body segment in order to determine the mechanical properties of the padding material. The aim of this study is to determine the tolerance of the human pelvis. This study takes into account results of 36 impact tests against the pelvis of 10 cadavers and proposes injury criteria values to characterize the risk of pelvic fracture. |
Vehicle Design Considerations For Older Drivers | During the next half century, the older driver population will increase dramatically as the Baby Boom becomes a Senior Boom of similar proportions. Therefore a proper understanding and awareness of the changes that take place in our vision and cognition through aging, can be useful to engineers designing automobile systems for a more mature market. How these changes brought about by aging affect our interaction with such vehicle systems as controls and displays, mirrors, head-lighting, seating, and entry and exit is the subject of the following discussion. Recommendations also are made, based upon the current literature, for modifying these vehicle systems to meet the needs of older drivers. |
Physical Characteristics Of Heat-Absorbing Glass And Their Influence On The Driver | The characteristics of heat-absorbing glass for passenger cars are described with regard to climate perception and visibility of the driver, both of which are important aspects of active safety. Such modern types of glass reduce the transparency to heat and at the same time maximise light in the visible spectrum. To be in a position to quantify the advantages and disadvantages in the visible spectrum as regards transparency, dazzling, reflectance and diffused light, practical road-test runs were carried out on the same public roads under different conditions in light and climatic environmental. The tests comprised physico-technical, physical and psychological data with regard to driving behaviour of and strain on the drivers. The results confirm the predominance of advantages of heat-absorbing glass and provide, indications as to optimising the side and rear windows by increasing the degree of heat-absorbing. |
Investigation of Vehicle Side Impact Stiffness - Comparison of Static and Dynamic Tests | The purpose of this investigation on vehicle side-impact stiffness and the comparison of the static and dynamic tests was to contribute guidelines for a final test procedure with two advantages: to be, on the one hand, simply practicable and reproducible and, on the other hand, to provide results corresponding as close as possible to real accidents. Additionally, the investigation emphasized testing of side parts significant to the objectives of the test: door only, door and sill, or door, sill and roof. New cars as well as heavily rusted vehicles were used for the test. Therefore this paper also treats the question of what degree a test of only new cars will be useful, without considering the state of corrosion of older vehicles. |
A Study of the Vehicle Acoustic Control for Booming Noise Utilizing the Vibration Characteristics of Trunk Lid | An acoustic control technique for reducing booming noise caused by road surface roughness is described. This noise, mainly in the frequency range between 25 and 40Hz and accompanied by a pressure sensation, is closely related to suspension vibration characteristics and the acoustic response of the vehicle compartment. A reduction method which separates the highest acoustic response from suspension resonance in this frequency region is proposed. An acoustic simulation model is used to estimate the effects of the luggage compartment on this noise and of trunk lid vibration characteristics in optimizing acoustic properties of the compartment. As a result, a frequency region for trunk lid resonance which lowers booming noise is obtained. Estimated booming noise reduction is experimentally confirmed in road tests. A study of human auditory characteristics is also conducted to ascertain the frequency range and booming noise level which produce uncomfortable sensations. |
Prevention of Frost Formation on Automobile Glazing | Energy radiation during clear mornings causes a temperature drop on outdoor surfaces. If this drop is big enough, moisture will condense and lead to frost formation during cold weather. This is a nuisance and a safety risk for the driver when it occurs on car windows. If the surface of the glazing is coated so that the emissivity within certain spectral bands is low, frost formation can be prevented in most situations. In the autumn of 1986, Volvo introduced a windshield on these lines. Tests indicate that the number of mornings when scraping is necessary is reduced by more than 80% in the Swedish coastal climate. |
Special Considerations in Outfitting a Space Station Module for Scientific Use | This paper addresses some of the key issues involved with outfitting a space station module for life sciences research, namely the integration of a large diameter centrifuge for holding control specimens at 1G (or fractions thereof); accommodating international participation in the design and construction of key elements of the lab module (including the module itself); and maintaining biological isolation between the experimental animals and the crew. Several design concepts are presented that address these specific issues. Centrifuge vibration - once thought to be a major problem in a station that also houses materials technology experiments - will be virtually eliminated by the use of an active magnetic suspension and automated rotor balancing. Bioisolation is provided by housing the animals in special isolator cages and performing all experimental work in a laminar flow isolation hood. |
Performance Criteria for Speakers in Digital Car Audio Systems | In an automotive sound system, the environment plays a major role in the total acoustical performance. Most of the design goals are the same as in home entertainment systems. However, the presence of road noise and restricted space availability for the speaker location must be considered as design criteria. High excursion requirement to overcome the masking effects introduces several nonlinearities. Since cars behave differently under dynamic conditions, speakers must be designed selectively for high performance. |
Machine Vision Correlation to Master Gauges | Machine vision technology is a tool being utilized in the new GMT-400 pickup truck Body Shops for process monitoring and control. These real-time Machine Vision Dimensional Gauging systems monitor 100% of the production's critical build features such as door and window openings, hinge locations, and fender mounting brackets, Traditional gauges typically can provide data on only a small sample of production ??% or less. Correlating the machine vision systems to master gauges allows accurate data to be collected on every job as it is being built. This complete dimensional control data provides information for process monitoring as well as a means to detect tooling adjustment requirements and the ability to detect build problems, even if they occur intermittently. Several methods of performing this correlation have been investigated, with the goal being to define a correlation procedure that works well in the plant environment. |
Study of the Hydrodynamic and Viscoelastic Properties Affecting the Surface Appearance of Extruded EPDM Compounds | An experimental study was aimed at understanding the mechanisms establishing the surface appearance of extruded EPDM compounds for applications where aesthetic appearance is critical. The study shows that surface appearance is directly proportional to the extent of viscous heating in the die, and hence can be controlled by the degree of shearing action, either by screw and die design or screw speed. Both surface appearance and extrudate swell can be related to the viscoelastic properties of the EPDM polymer through the dimensionless Deborah and Euler numbers. Knowledge of the parameters affecting surface appearance can be applied to better design of EPDM polymers for such applications as automotive seals for windows and doors, which are comprised of both dense and sponge extruded profiles. |
A Body Switching System using the SAE J1850 (CarLink) Protocol | The recent approval by the SAE Motor Vehicle Council of the serial protocol J1850 is a major milestone in the development of an open and flexible network approach to vehicle wiring. However, it is now necessary to evaluate the practical implementation of the protocol in some real vehicle applications. This paper describes one such exercise which considers a three station installation including the doors and a central body computer function, together with a diagnostic capability. It is, of course, anticipated that this simple system will be extended to include other areas of the vehicle as confidence is gained in its performance and the benefits of system integration are realised. |
Numerical Simulation of Air and Heat Flow in a Heater Unit | Heat flow phenomena in the heater unit of an automobile air conditioning system have been analyzed by direct simulation, solving the Navier-Stokes' equation in which an upwind finite difference method of third-order accuracy is adopted with a 2-D model. The analytical results presented visually to ascertain air and heat flows in the heater unit. In addition, a comparative experiment was carried out to compare test results with calculated results. The heater unit in the air conditioning system controls the temperature of air in the automobile. The heater unit consists of a unit inlet, outlet, mixing door and heater, as shown in Fig. 1 (1). Air, entering the heater unit inlet is mixed with warm air heated by the heater to a suitable temperature, and then blown out of the outlet. The shape and size of the heater unit are restricted by the size of an automobile's engine compartment and the layout of other auxiliary devices. Therefore, warm air must be mixed with cool air efficiently in this limited space. The shape of the heater unit has been determined based on experience. The development of the heater unit requires a fairly long period of time and much labor. To improve the efficiency of this development process, the authors quantitatively analyzed air mixing phenomena in the heater unit. The Navier-Stokes' equation was solved directly by the third-order accuracy upwind method. |
A Low Cost Door Control System | The ability to achieve a low-cost replacement for the conventional wiring harness is difficult when considering a multiplexing system designed for a minimum wire count. This paper looks at a specific problem - getting a large number of cables across the ?쁀 post??into the driver's door, and considers the issues affecting the design of partially multiplexed solutions. A summary of the technical and cost implications of the new system is included. |
Electrochemical Metallizing, Tooling Design, and Application | Electrochemical metallizing (ECM) has been widely used in aircraft maintenance and OEM applications, but is far from reaching it's potential. Although ECM has been around for more than twenty years, it still represents a small part of metal finishing as a whole, thus making information describing the process not readily available. Most of the problems experienced with the process, aside from solution contamination, stem from improper tooling design, and will be the focus of this paper. Tooling and other areas covered will be as follows: 1 Anode design: choosing proper anode design for the job. 2 Flow-thru anodes: for more efficient distribution of electrolytes. 3 Precision build-ups: plating to size. 4 Solution and anode cooling: to prevent over-heating of solutions at the anode/work-piece interface and the effects on the deposit. 5 Masking techniques: how to make the tape work for you by reducing high and low current density problems. 6 Heavy build-up: depositing .050??or more. This paper will cover areas which help us get closer to creating ideal ECM conditions, therefore improving repeatability and opening doors to new applications. |
Fabrication of Interior Door Trim Using Ceramic Dies | To produce high quality appearance interior parts, precise pattern forming or gloss reduction of three-dimensional door trim cover materials are utilized. In the preparation of formed trim cover using polyvinyl chloride (PVC), prior pattern forming on original cover material or post-pattern forming with vacuum forming dies are employed. In the latter case, the die is usually made of epoxy resin. Although vacuum holes are prepared on the resin die as necessary, the lack of uniformity in air permeability causes inferior pattern transferability. In this development, special porous ceramic die is used as die material so that trim cover material can be evenly sucked through the fine pores on its surface. As a result, a door trim forming die of superior pattern transferability has realized. The features of this- die are as follows. 1) The addition of metal powder, metal fiber, and binder to the ceramic powder has achieved well balanced air permeability, compressive strength, and dimensional change rate. 2) The uniform, high air permeability can produce deep and precise grain and stitching pattern (patterns) transfer with a low surface gloss rate. A work area with a stable surface quality can also be secured. 3) A shorter lead time of manufacturing and lower die making cost have achieved. |
A Steel-Plastic Hood Concept for Passenger Cars | A novel hood of steel and plastic has been designed to achieve an effective balance between weight and cost. The design concept uses a thinner (lighter weight) 0.024-inch-thick steel sheet for the outer component and a compression molded SMC inner component combined with an inner very thin (0.015-inch-thick) steel sag pan. Cost estimates of the hybrid hood were made using a mathematical cost model developed by MIT and indicated costs similar to an all-steel hood, but significantly lower than for an all-SMC hood. In addition, the weight of the hood is less than the all-steel hood. The steel outer optimizes the surface characteristics of the hood and maintains appearance compatibility with other exposed steel body panels. The inner steel sag pan is used in membrane tension to work with and complement a minimal weight SMC panel. The inner SMC portion also acts in compression and bending to significantly limit panel deflections and greatly increase the assembly's stiffness. Key adhesive bonding tests were successfully conducted with bare and coated steel substrates selectively bonded to SMC during the SMC molding cycle. The encouraging engineering analysis of the novel hood and the attractive combination of low weight and cost suggest that similar benefits could be derived from combining steel and plastic in other two-piece assemblies (deck lids and doors). |
Development of Practical Multiplexed Wiring System | This paper describes a new approach to solving various problems inherent in conventional multiplexed wiring systems. These problems include the fact that the quantity of cut leads, which determines the cost, is not reduced even though the bulk of the wire harness is decreased. Another problem is that the communications system has a very complex configuration. With the approach proposed here it has been found that the number of cut leads can be reduced by housing the communications circuits individually in each piece of electrical equipment. This can be accomplished by grouping together the wiring in which the signals activating electrical load units all flow in the same direction. Custom LSI circuits have been developed to simplify the communications circuits. All of these developments have been combined into practical multiplexed wiring systems for controlling the power Windows, automatic door locks and power seats. |
Energy Management of Thermoplastic Composites in Automotive Instrument Panels/Components: An Option for FMVSS 208 | Federal requirements for unrestrained occupant protection, recent automotive designs requiring increased part integration and modular assemblies, high costs for tooling and secondary operations, and intensifying competition are primary incentives for automotive engineers and designers to consider thermoplastic composite materials for replacing and complementing many current metal parts. Nowhere is the scrutiny of material choice more significant than in parts where energy management and stiffness are major design concerns; parts such as bumper beams, door structures, seating, and instrument panel components. Thermoplastic composites offer designers materials which are lightweight, perform consistently over wide temperature ranges, and manage energy to meet part performance requirements. |
An Integrated Door System Using Multiplexing | Many separate door systems are integrated into a single functional system that uses multiplexed wiring techniques. This system shows advantages over conventional techniques in many areas. Some of the advantages are: Reduced wiring, less part numbers, reduced car-to-car variability, increased functions, better build, and better servicing. |
Door Module of Polyurethane: A New Concept | This is a specification for a car door made of polyurethane plastics with the following features: Door body of GF/PU combined with an integrated metal support. The outside door panel from the waist line down to the bottom edge of the door is fixed to the door body with an adhesive-bonded joint. A metal support designed as a stiffening frame and a supporting element for fittings. Permanently bonded, form-fitting window combined with multi-purpose window that can be lowered. The costs show that this concept is able to compete with conventional metal solutions. |
Ten Years of Plastic Applications in Fiat Car Exterior Components: Review and Preview | The paper outlines the evolution of the plastic component in Fiat passenger cars as far as the outerpart is concerned. A first section is devoted to bumpers and their evolution into front and rear ends where different materials (thermosetting and thermoplastic ones) and finishing procedures (grained in-mass pigmented or smooth and painted) were adopted. Further the evolution of a rear door is quoted dealing with the design concept of two wall adhesivated structure and with the selection of the appropriate manufacturing technology. In conclusion, taking also care of the service performances, trouble shooting and technology evolution during the last ten years, some considerations are quoted, demonstrating that the approach to fully plastic body panels will require in each case peculiar studies and development works. |
Car Occupant Ejection in 919 Sampled Accidents in the UK-1983-86 | Vehicle and injury data from 919 accidents in the UK are analysed for frequency, cause, and consequences of occupant ejection. Injury consequences are shown to be severs, the fatality rate rising with ejection by a factor of 4.3 among unrestrained occupants, and evidence is offered that ejection prevention would reduce injury levels to those of not-ejected occupants. The rear window was found in this sample to be the most frequent ejection route, followed by side doors, side glass, and the tailgate. Complete ejection was slightly more frequent from hatchbacks than from saloons. Door openings are analysed for frequency and release mechanism, and the ejection risk for exposed occupants is seen to be very high. These results are considered in relation to possible countermeasures, of which restraint use is shown to be by far the most effective, and bonded laminated or glass-plastic glazing is particularly recommended for rear windows. |
New Developments in Materials and Fabrication Processes for Automotive Interior Trim Skin Materials | Automotive interiors consist of sandwich type components (e.g., instrument panel, door trim, headliner); hard trim (e.g., pillar trim) and functional solid components (e.g., load floor, seat backs, etc.) The intermaterials competition among new processes for fabricating these 3 types of components were described previously (1)*. This paper examines new developments specifically in the area of skin materials used for the sandwich type interior trim components. |
A Survey of Vehicular Side Wall Constructions | Starting with the vintage flat built up side wall constructions in the form of door and quarter trim panel trim, this paper discusses the resinated felt, wood fiber, filled plastic extruded sheet, injected molded, molded in place, reinforced reaction injection molded (RRIM), structurally reinforced reaction injection molded (SRIM) side wall constructions. It further discusses cover materials for interior trim in the United States, Europe and the Orient. The future trends along with modular doors are discussed. A conclusion is made regarding the responsibility to be undertaken as assigned by the end using customer. |
Application Study of Vibration Damping Composite Steel Sheet to the Car Body Panels | The vibration damping composite steel sheet was improved in properties such as dependence on temperature, bending rigidity, press formability and spot weldability and compared with damping materials currently used by reviewing composition and adhesion strength of the resin and the mechanical property of the steel skin sheets. By applying the above-mentioned materials to the floor and wheel-house panels, a reduction in noise and vibration was obtained in the application test, and improvement in door shutting noise was also revealed when applying these materials to the door panels. |
Relationship Between the Physical and the Psychoacoustic Parameters of the Sound Field in an Automobile | A new method of measuring physical factors that prescribe the sound field of the vehicle interior has been used to evaluate the differences in the sound field for 4 types of two-channel loudspeaker systems, which are installed in the front part of the vehicle. The physical property which prescribes the sound field inside the vehicle is related to the directional properties of the sound, such as lateral, forward and backward component of the early reflection sound energy. Psychological experiments have also been conducted under the same conditions as that for the physical measurement, and then the correlation between the psychological factor and the physical factor has been examined. The following conclusions have been reached: (1) L/M (the ratio of low frequency sound energy vs. medium frequency sound energy) is highly correlated with spatial impression. (2) F/B (the ratio of forward directional energy vs. backward directional energy) greatly contributes to the preference of the sound quality. (3) L/R (the ratio of left directional energy vs. right directional energy) is highly correlated with the localization (left and right) of the sound image. (4) Among the four types of two-channel loudspeaker systems, ?쐌ounted in the front doors??has a wide sound image and is more preferable in comparison with the other loudspeaker locations. |
Status and Update of MVMA Component Testing | At the Tenth ESV Conference, MVMA reported on the development of a component side impact test device developed for MVMA by MGA Research Corporation. Since that time, the test device has been modified by MGA to improve its biofidelity. Testing has shown that the modified device better meets the force-time corridors derived by MVMA from cadaver drop test data. The improved test device was used to test twelve 1985 Ford LTD doors at speeds of 25.7 and 37 km/h. The interior door surfaces were trimmed with either thin fiber board or foam padding identical to doors in vehicles tested by MVMA using NHTSA's full-vehicle test procedure. The tests showed that the MVMA device is simple to set up and run, is highly repeatable and easily discriminates between the unpadded and padded doors. A major issue for future research and development is how to select a priori a component test device impact speed which can account for differences in car size and side structure stiffness. |
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 ?쐇nterplate 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 ?쐀ent 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 ?쏤lexible??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 횞 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. |
?쏰ptimization??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 ?쏱allets??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-Trac짰 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 ?쐀oom??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 ?쏝rand 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 ?쐃xcellent??acoustics and criteria and tools for acoustic evaluation. Focusing on the HVAC subsystem ?쏿ir 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 3쩍 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. |
?쏯ext 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 ?쏶OQCRATES??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 ?쐓elfteaching?? 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 ?쐓kins?? 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?셲 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 ?쐔ransflect??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. |
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