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Sound package engineering has always been an art developed through experience and much subjective road testing. Because the problem is complex, it is essential to have a logical procedure to achieve the most efficient sound package. The quiet car concept is proposed as a solution. Additionally, a plea is made for relevant automobile-oriented material test procedures to be recognized industry-wide.

This paper presents the extended Kalman filter-based sideslip angle estimator design using a nonlinear 5DoF single-track vehicle dynamics model with stochastic modeling of tire forces. Lumped front and rear tire forces have been modeled as first-order random walk state variables. The proposed estimator is primarily designed for vehicle sideslip angle estimation; however it can also be used for estimation of tire forces and cornering stiffness. This estimator design does not rely on linearization of the tire force characteristics, it is robust against the variations of the tire parameters, and does not require the information on coefficient of friction. The estimator performance has been first analyzed by means of computer simulations using the 10DoF two-track vehicle dynamics model and underlying magic formula tire model, and then experimentally validated by using data sets recorded on a test vehicle.

This paper explores the extent to which standard dilution tunnel measurements of motor vehicle exhaust particulate matter modify particle number and size. Steady state size distributions made directly at the tailpipe, using an ejector pump, are compared to dilution tunnel measurements for three configurations of transfer hose used to transport exhaust from the vehicle tailpipe to the dilution tunnel. For gasoline vehicles run at a steady 50 - 70 mph, ejector pump and dilution tunnel measurements give consistent results of particle size and number when using an uninsulated stainless steel transfer hose. Both methods show particles in the 10 - 100 nm range at tailpipe concentrations of the order of 104 particles/cm3.

Brake related warranty costs are a major concern to the automotive industry. Large part of these costs are due to noise, more particularly due to the brake squeal complaints. Computer-aided engineering solutions have attracted a lot of attention from the engineering and development community for more effective brake product development. Recently, three brake squeal analysis methods were implemented on disc type brakes in a vehicle program at Ford. This paper summarizes the results and documents the experience obtained during implementation in the vehicle CAE process.

Due to several indeterminate factors, the assessment of the durability performance of a vehicle body is traditionally accomplished using test methods. An analytical fatigue life prediction method (four-step durability process) that relies mainly on numerical techniques is described in this paper. The four steps comprising this process include the identification of high stress regions, recognizing the critical load types, determining the critical road events and calculation of fatigue life. In addition to utilizing a general purpose finite element analysis software for the application of the Inertia Relief technique and a previously developed fatigue analysis program, two customized programs have been developed to streamline the process into an integrated, user-friendly tool. The process is demonstrated using a full body, finite element model.

Applying a variable reluctance sensor to a differential odometer application requires special considerations. Due to widespread use in anti-lock brake systems and the need for cost effective designs, variable reluctance sensors have advantages over more expensive active sensors. Unfortunately, both mechanical and electrical parameters can adversely affect the output of a variable reluctance sensor. The output signal varies with the rate of change of the flux, mechanical spacing and magnetic source variation. At low vehicle speeds the output signal, which is a function of the rate of change of the flux, tends to approach zero and signal-to-noise ratios become significant. Since changes in vehicle direction typically occur at lower speeds, differential odometers require good low speed performance. In addition to speed, differential odometers rely on two sensors, therefore sensor variation must also be compensated for.

An experimental modal model of an early prototype car was constructed and validated against test results. The model was then used to suggest practical hardware modification alternatives which would: (1) shift the steering column resonant frequency away from the idle range, and (2) maintain a low steering column tip vibration within the 600-750 RPM idle range. This model was also used to evaluate the effectiveness of tuning radiator mounts to the overall vehicle idle quality. It was found that a pair of braces from either the steering column bracket to brake pedal bracket or to the cowl top area could improve idle shake of the test vehicle. The driver side brake pedal brace alone is not effective. However, the passenger side brake pedal brace alone is as effective as the two brake pedal braces together. It was found that the radiator mounts on the test vehicle are extremely non-linear. Therefore, tuning the mount to improve idle quality is impractical.

During frontal and rear end type collisions, very large forces will be imparted to the passenger compartment by the collapse of either front or rear structures. NCAP tests conducted by NHTSA involve, among other things, a door openability test after barrier impact. This means that the plastic/irreversible deformations of door openings should be kept to a minimum. Thus, the structural members constituting the door opening must operate during frontal and rear impact near the elastic limit of the material. Increasing the size of a structural member, provided the packaging considerations permit it, may prove to be counter productive, since it may lead to premature local buckling and possible collapse of the member. With the current trend towards lighter vehicles, recourse to heavier gages is also counterproductive and therefore a determination of an optimum compartment structure may require a number of design iterations. In this article, FEA is used to simulate front side door behavior.

The purpose of this paper is to describe and define the interaction between a brake based stability control system and a passive coupler (viscous coupling unit) inside the transfer case of a Four-Wheel Drive (4WD) vehicle. This paper will focus on the driveline system and the impact that a stability control system can have on it. It will provide understanding of torque transfer on 4WD vehicles that are equipped with a brake based stability control system and use this knowledge to recommend ways to reduce the undesirable torque transfer interaction between the two systems. These recommendations can be readily applied to future 4WD/AWD vehicles to improve compatibility between the two systems.

This paper identifies and analyzes steady-state and transient tire properties affecting vehicle directional response characteristics. The study is limited to the relationship between lateral force and slip angle. It shows fundamental differences between steady-state and transient properties. Tire transient properties are described by a force-slip angle loop with cornering stiffness and dynamic lateral force offset as parameters. Cornering stiffness is presented as a variable that changes with speed and steer rate. An interrelationship between cornering stiffness and dynamic lateral force offset resulting from the time lag between lateral force and slip angle is shown. Ramp steer techniques for measuring transient tire properties on a road trailer and on an external drum machine are described. A need for transient tire data for computer simulations of vehicle transient steer maneuvers is shown.

Traction drive continuously variable transmissions (TCVTs) are under active investigation by a number of OEMs and suppliers. Along with advances in control systems and metallurgy, improved traction fluids will be key to successful implementation of this technology. Traction fluids will need to function over a wide range of temperatures and contact pressures. Contact pressures may reach as high as 4 GPa, while temperatures may range from about - 40 C to about 140 C. It is widely recognized that low temperature fluidity at start-up is an issue, since fluids which give high traction coefficients and adequate viscosity under normal operating temperatures generally exhibit high viscosity at low temperatures. However, fe published data are available on traction behavior at temperatures below about 20 C and at contact pressures above about 2 GPa.

An experiment has been conducted to study the effect of vehicle alignment, tire construction and operational conditions on tire treadwear. The Taguchi approach was used to compose the experimental design and to analyze the data. The treadwear testing was conducted on the indoor test machine; this test duplicates the treadwear pattern observed during road test. The responses of interest were total wear, irregular wear patterns, and diagonal wear. The study quantified the relative importance of different factors to treadwear and also the degree of wear irregularity.

A tire on a vehicle is not a separate entity to be considered only in itself. The tire is part of the entire vehicle and this entire vehicle must be considered in making tire selections. Just as important are the components of a tire and the various parameters to be considered in tire design. Care must be taken that any attempt to optimize a single parameter does not jeopardize the overall quality.

The recent development of TiAl-based alloys by the aerospace community has provided an excellent material alternative for hot components in automotive engines. The low density combined with an elevated temperature strength similar to that of Ni-base superalloys make TiAl-based alloys very attractive for exhaust valve applications. Lighter weight valvetrain components improve performance and permit the use of lower valve spring loads which reduce noise and friction and enhance fuel economy. However, difficult fabricability and a perception that TiAl alloys are high cost, low volume aerospace materials must be overcome in order to permit consideration for use in high-volume automotive applications. This paper provides a comparison of properties for several exhaust valve alternative materials. The density of TiAl alloys is lower than Ti alloys with creep and fatigue properties equivalent to IN-751, a current high performance exhaust valve material.

Splash and spray conditions created by tractor-trailer combinations operating on the Federal highway system have been studied and tested for many years with mixed results. Past events are reviewed briefly in this paper. In additional testing during 1983, using new state-of- the-art splash/spray suppressant devices, some encouragement was provided that these devices could work. The 1984 Motor Vehicle Manufacturers Association (MVMA) test program was designed to develop practicable and reliable test procedures to measure effectiveness of splash and spray reduction methods applied to tractor-trailer combination vehicles. Over 40 different combinations of splash/spray suppression devices on five different tractors and three van trailer types were tested. The spray-cloud densities for some 400 test runs were measured by laser transmissometers and also recorded by still photography, motion pictures, and videotape. On-site observers made subjective ratings of spray density.

Gas carburized and quenched low alloy steels typically produce surface microstructures which contain martensite, retained austenite and often NMTP's (non-martensitic transformation products). The NMTP's are caused by a reduction of surface hardenability in the carburizing process from loss of alloying elements to oxidation. Gas carburized low alloy steels such as SAE 8620 with NMTP's on the surface have been shown to have inferior bending fatigue properties when compared to more highly alloyed steels which do not form NMTP's, such as SAE 4615M. One method of minimizing the formation of oxides and eliminating NMTP formation during carburizing and quenching is to use plasma carburizing instead of conventional gas carburizing. In this study the microstructures and bending fatigue performance of plasma carburized SAE 8620 and SAE 4615M is compared to the same alloys conventionally gas carburized and quenched.

This paper discusses a motor vehicle noise source identification technique designed for use during the SAE J986a or similar drive-by test procedure. It provides, by application of the Fourier Transform, the capability to obtain a narrowband (9.8 Hz) frequency resolution over an extended frequency range (0-10,000 Hz) at the peak vehicle noise level, a particular RPM, or a particular vehicle location in the test zone. Other features include corrections for the Doppler shift, averaging of noise tests, and subtraction of spectra of two separate noise tests from a component disconnect/reconnect procedure. The above analysis, in conjunction with the noise source isolation resulting directly from the disconnect procedure, identifies the major vehicle noise contributors in terms of their respective amplitudes and frequencies.

This paper describes the rapid development of the Ford GT transmission, from concept phase to production, where the technical challenges involved are implicit in the specifications provided. It presents the steps taken at a project management level to expedite development, as well as the tools used to design and rate components at the design stage. Examples of concurrent engineering are given as well as management techniques used to predict and address key risks. In addition, details of analysis and test procedures are given, underlining their contribution to the rapid introduction of the transmission to the market place.

FORD'S answer to the air suspension problem is a system of the “open” type in which the air is exhausted from the springs to the atmosphere. It features a 2-speed automatic height and leveling control to handle differing load conditions. In adapting the air springs to the suspension arms, the front suspension was modified only slightly, while the rear was completely redesigned. The author reports that a significant improvement in passenger comfort has been achieved with the new suspension, especially for the rear seat passenger. Also, the car height remains constant under all loadings—a contribution to the car's appearance.

A small-scale oxidation test for automatic transmission fluids has been developed. In the test air flow rates, temperature and catalytic activity can be closely controlled at desired levels. A test procedure for screening automatic transmission fluids is described. Data are presented illustrating the ability of the test to distinguish between different levels of oxidation resistance, the repeatability of the test, and the correlation achieved thus far with a presently used full-scale transmission oxidation test.