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The demand for improved fuel economy in both cars and trucks has emphasized the need for lighter weight components. The application of high strength steel to wheels, both rim and disc, represents a significant opportunity for the automotive industry. This paper discusses the Ranger HSLA wheel program that achieved a 9.7 lbs. per vehicle weight savings relative to a plain carbon steel wheel of the same design. It describes the Ranger wheel specifications, the material selection, the metallurgical considerations of applying HSLA to wheels, and HSLA arc and flash butt welding. The Ranger wheel design and the development of the manufacturing process is discussed, including design modifications to accommodate the lighter gage. The results demonstrate that wheels can be successfully manufactured from low sulfur 60XK HSLA steel in a conventional high volume process (stamped disc and rolled rim) to meet all wheel performance requirements and achieve a significant weight reduction.

An extensive calibration study has been initiated to assess the predictive ability of CFD (Computational Fluid Dynamics) for the aerodynamic design of automotive shapes. Several codes are being checked against a set of detailed wind tunnel measurements on ten car-like shapes. The objective is to assess the ability of numerical analysis to predict the CD (drag coefficient) influence of the rear end configuration. The study also provides a significant base of information for investigating discrepancies between predicted and measured flow fields and for assessing new numerical techniques. This technical report compares STAR-CD predictions to the wind tunnel measurements. The initial results are quite encouraging. Calculated centerline pressure distributions on the front end, underbody and floor compare well for all ten shapes. Wake flow structures are in reasonable agreement for many of the configurations. Drag, lift, and pitching moment trends follow the experimental measurements.

This paper reports the analytical procedure developed for a simulation of knee impact during a barrier crash using a hybrid III dummy lower torso. A finite element model of the instrument panel was generated. The dummy was seated in mid-seat position and was imparted an initial velocity so that the knee velocity at impact corresponded to the secondary impact velocity during a barrier crash. The procedure provided a reasonably accurate simulation of the dummy kinematics. This simulation can be used for understanding the knee bolster energy management system. The methodology developed has been used to simulate impact on knee for an occupant belted or unbelted in a frontal crash. The influence of the vehicle interior on both the dummy kinematics and the impact locations was incorporated into the model. No assumptions have been made for the knee impact locations, eliminating the need to assume knee velocity vectors.

This report should not be looked upon as an end in itself, but rather as a thought provoker. It raises the question that there may be an additional dimension to race car aerodynamics other than just open roadway drag reduction, stability and handling performance. Some situations are seldom considered, nor even addressed, in public forums. Based upon wind tunnel test data, the authors show, at least for this one test setup, that significantly large changes in aerodynamic forces can be generated on a NASCAR stock car racer by its close proximity to the stationary retaining wall around a race track.

A four-stroke, spark-ignition engine is described that seeks to achieve high expansion ratio and low throttling losses at light load, whilst retaining good knock resistance at full load operation and without the need for expensive mechanical changes to the engine. The engine does, however, incorporate a second inlet (transfer) valve and associated transfer port linked to the intake port. The timing of the transfer valve is different from that of the main inlet valve. Load modulation is achieved by control of the gas outflow from the transfer port. A computer model of the engine is first validated against measured data from a conventional engine. Comparisons are made of incylinder pressure at part load conditions, total air flowrate through the engine and intake port air velocities as a function of crank angle position.

A microcomputer-based, multichannel data acquisition system has been developed to acquire high frequency transient information typified by, but not limited to, automotive vehicle crash test applications. The system, which has been designed to be mounted on the test vehicle during a vehicle crash, will accommodate up to 240 channels. Each channel is comprised of a stand-alone microcomputer, memory for data storage, signal conditioning for piezoresistive transducers, automatic calibration and zero offsets, and programmable gain amplifier. The microcomputer is based upon a Motorola 6801/68701 microcomputer. The paper describes the design, development, and data processing characteristics of the prototype system.

The crush performance of lightweight composite automotive structures varies significantly between static and dynamic test conditions. This paper discusses the development of a new dynamic testing facility that can be used to characterize crash performance at high loads and constant speed. Previous research results from the Energy Management Working Group (EMWG) of the Automotive Composites Consortium (ACC) showed that the static crush resistance of composite tubes can be significantly greater than dynamic crush results at speeds greater than 2 m/s. The new testing facility will provide the unique capability to crush structures at high loads in the intermediate velocity range. A novel machine control system was designed and projections of the machine performance indicate its compliance with the desired test tolerances. The test machine will be part of a national user facility at the Oak Ridge National Laboratory (ORNL) and will be available for use in the summer of 2002.

Various algorithms such as a direct computation approach, maximization requirement criteria method established by Chou and Nyquist, and a partitioning technique, for computing HIC are reviewed in this paper. An evaluation has been conducted considering both the accuracy and efficiency of these algorithms using theoretical pulses and experimental resultant head accelerations of a dummy obtained from the literature, Hyge sled and frontal barrier impact tests. Using results obtained from direct computations as “exact” values for comparison, all the algorithms evaluated provide HIC estimates in close agreement with the “exact” values. The CPU times, which are used as a measure for the assessment of computational efficiency, vary from algorithm to algorithm. Methods using a partitioning logic developed by Mentzer and a faster algorithm developed by Holstein and Alem are found to be very efficient, and are recommended for use in the computation of HIC.

In vehicle crash tests, an unbelted occupant's kinetic energy is absorbed by the restraints such as an air bag and/or knee bolster and by the vehicle structure during occupant ride-down with the deforming structure. Both the restraint energy absorbed by the restraints and the ride-down energy absorbed by the structure through restraint coupling were studied in time and displacement domains using crash test data and a simple vehicle-occupant model. Using the vehicle and occupant accelerometers and/or load cell data from the 31 mph barrier crash tests, the restraint and ride-down energy components were computed for the lower extremity, such as the femur, for the light truck and passenger car respectively.

This paper presents the progress of an ongoing vehicle micro corrosion environment study. The goal of the study is to develop an improved method for estimating vehicle corrosion based on the Total Vehicle Accelerated Corrosion Test at the Arizona Proving Ground (APG). Although the APG test greatly accelerates vehicle corrosion compared to the field, the “acceleration factor” varies considerably from site-to-site around the vehicle. This method accounts for the difference in corrosivity of various local corrosion environments from site-to-site at APG and in the field. Correlations of vehicle microenvironments with the macroenvironment (weather) and the occurrence of various environmental conditions at microenvironments are essential to the study. A comparison of results from APG versus field measurements generated using a cold rolled steel based corrosion sensor is presented.

Most automobiles, at certain speeds with at least one window open, develop a pulsating pressure which is felt mainly through the ears and is objectionable to the occupants. While this “aerodynamic wind throb” is noticeable over a range of speeds, there is a fairly pronounced peak in the effect at one speed. This problem is studied analytically and experimentally. It is established that the car is a dynamic system consisting of a Helmholtz resonator excited by an edge tone. It is shown that the trouble can be corrected by changing the natural frequency, minimizing or eliminating the excitation, or increasing damping of the system.

Vehicle body with aluminum riveted construction instead of steel welded one will be a big challenge to NVH. In this paper, aluminum and steel rails with the dimensions similar to the rear rail portion of a typical mid-size sedan were fabricated. Rivets were used to assemble the aluminum rails while welds were used to assemble the steel rails. Adhesive, rivet/weld spacing, and rivet/weld location were the three major factors to be studied and their impact on NVH were investigated. The DOE matrix was developed using these three major factors. Modal tests were performed on those rails according to the DOE matrix. The FEA models corresponding to the hardware were built. CAE modal analysis were performed and compared with test data. The current in-house CAE modeling techniques for spot weld and adhesive were evaluated and validated with test data.

The viscous criterion (V*C) has been proposed by biomechanics researchers as a generic biomechanical index for potential soft tissue injury. It is defined by the product of the velocity of deformation and the instantaneous compression of torso and abdomen. This criterion requires calculation and differentiation of measured torso/abdomen compression data. Various computational algorithms for calculating viscous criterion are reviewed and evaluated in this paper. These include methods developed by Wayne State University (WSU), NHTSA (DOT) and Ford. An evaluation has been conducted considering the accuracy of these algorithms with both theoretical and experimental data from dummy rib compressions obtained during a crash test. Based on these results, it is found that: V*C results depend on the scheme used in the computation process, the sampling rate and filtering of original raw data. The NHTSA method yields the lowest V*C value.

The SAE Large Male and Small Female Dummy Task Group has recommended a change to the Hybrid III dummy hip joint. This change was made because of a non-biofidelic interference in the current design that can influence chest accelerations. The modifications include a new femur casting shaft design and the addition of an elastomeric stop to the top of the casting. Static testing and Hyge sled tests were done to evaluate the modifications. Based on the results, the new design satisfied the requirements set by the SAE task group and reduced the influence of hip joint characteristics on chest accelerations.

Sliding door designs are applied to rear side doors on vans and other large vehicles with a trend towards dual sliding doors with power operation. It is beneficial for the vehicle user to reduce the weight of and space occupied by these doors. Alcoa, in conjunction with Ford, has developed a multi-product, multi-material-based solution, which significantly reduces the cost of an aluminum sliding door and provides both consumer delight and stamping-assembly plant benefits. The design was successfully demonstrated through a concept readiness/technology demonstration program.

Using instrumentation designed for the ultrasonic measurement of thickness, a technique has been devised for measuring the isotropic elastic constants of small samples, i. e., samples 1 mm in thickness and a minimum of 5 mm in other dimensions. Young's modulus, the shear modulus and Poisson's ratio are calculated from measurements of density and ultrasonic shear and longitudinal wave velocities. Samples of valve train materials, including chill cast iron, low alloy steel, tool steel, stainless steel, a nickel-base superalloy, and a powder metal alloy were machined from components and analyzed. The magnitude of the measured values of the elastic constants are reasonable when compared with published values. The measurement error on all the constants is estimated to be less than 1%. Moduli determined by this method can be used in finite element analyses to improve designs.

After establishing the performance requirements and initial design assumptions, CAE concept models are used to set targets for major structural components to achieve desirable crash performance. When the designs of these major components become available they are analyzed in detail using nonlinear crash finite element models to evaluate their performance. All these components are assembled together later in a full car model to predict the overall vehicle crash performance. If the analysis shows that the targets are met, the design drawings are released for prototype fabrication. When CAE tools are effectively used, it will reduce product development cycle time and the number of prototypes. Crash analysis methodology has been validated and applied for steel automotive product development. Recently, aluminum is replacing steel for lighter and more fuel efficient automobiles. In general aluminum has quite different performance from steel, in particular with lower ductility.

Dual Phase (DP) high strength steel is widely used in Europe and Japan for automotive component applications, and has recently drawn greater attention in the North American automotive industry for improving crash performance and reducing weight. In comparison with high-strength low-alloy (HSLA) steel grades with similar initial yield strength, DP steel has the following advantages: higher strain hardening, higher energy absorption, higher fatigue strength, higher bake hardenablility, and no yield point elongation. This paper compares the performance of DP and HSLA steel grades before, during, and after hydroforming. Computer simulation results show that DP steel demonstrates more uniform material flow during hydroforming, better crash performance and less wrinkling tendency.

Nowadays is a common sense the importance of the CAE usage in the modern automotive industry. The ability to predict the design behavior of a project represents a competitive advantage. However, some CAE models have become so complex and detailed that, in some cases, one just can not build up the model without a considerable amount of information. In that case simplified models play an important role in the design phase, especially in pre-program stages. This work intends to build an archetypal vehicle dynamics model able to predict the rollover resistance of a vehicle design. Through the study of a more complex model, carried out in Adams environment, it was possible to identify the key degrees of freedom to be considered in the simplified model along with important elements of the suspension which are also important design factors.

While testing vehicles for crash, particularly the offset frontal crash mode, new devices and techniques are needed to enhance the ability to measure rotations of certain vehicle components and dummy parts (or joints). The reason for this new demand is that the capabilities of existing techniques or devices in measuring rotations of small masses in confined areas are limited. Examples of the desired measurements are the rotations of dummy's feet and tibias as well as the rotations of the vehicle's toe-board during intrusion. These measurements help to understand dummy's ankle loads as a result of different intrusion rates. Furthermore, having these measurements is very beneficial to the validation of the computer models used in simulating the behavior of dummy's lower extremities in high intrusion crashes. Recent research demonstrated the use of an angular rate sensor, based on magnetohydrodynamic principles, on Hybrid-III dummies and cadavers.