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An experimental study was performed in order to determine whether or not ABS equipped automobiles leave skidmark signatures during emergency braking. The purpose of the study was to determine the feasibility of using conventional accident reconstruction methods on ABS equipped cars. Vehicles were braked from 65 mph (105 kph) on both asphalt and brushed concrete surfaces. A 1988 BMW 325 ES, a 1989 Mazda 626, a 1989 Nissan Maxima, a 1989 Oldsmobile Touring Sedan and a 1989 Toyota Supra Turbo were used as test vehicles. A 1987 Dodge Lancer, without ABS, was tested as a control vehicle. Data taken included stopping distance, skid mark lengths and deceleration rate. Vehicle handling and skid mark visibility were also noted. The experimental program showed that ABS equipped automobiles produce no discernable skidmarks under emergency, dry pavement braking conditions.

This set includes: Race Car Vehicle Dynamics, Race Car Vehicle Dynamics - Problems, Answers and Experiments Purchase both the book and the workbook as a set and save!

Written for the engineer as well as the race car enthusiast and students, this is a companion workbook to the original classic book, Race Car Vehicle Dynamics, and includes: Detailed worked solutions to all of the problems Problems for every chapter in Race Car Vehicle Dynamics, including many new problems The Race Car Vehicle Dynamics Program Suite (for Windows) with accompanying exercises Experiments to try with your own vehicle Educational appendix with additional references and course outlines Over 90 figures and graphs This workbook is widely used as a college textbook and has been an SAE International best seller since it's introduction in 1995. Buy the set and save! Race Car Vehicle Dynamics

At Indianapolis Motor Speedway (IMS), as well as at a large number of other tracks and temporary racing circuits, the pit lane is separated from the racing surface itself by a wall. The wall is intended to reduce the dangers to pit crew members, spectators and racers themselves, and to prevent interaction between racing and pitted cars. We examine the effectiveness of an attenuation device placed at the head end of the pit wall at IMS. Calculations are presented which show that the device can reduce the potential for injury to drivers by absorbing kinetic energy, by distributing the impact load over a large car area and by reducing and smoothing the acceleration pulse presented to the driver. Because driver restraint systems are not designed for high-g lateral loading, this attenuation represents a real safety feature in the case of a sliding situation. The device itself was (inadvertently) tested by a NASCAR vehicle during a practice session at IMS.

In the reconstruction of initial speeds from the evidence available in the aftermath of an impact, if there was appreciable post-impact spin, the effect of that spin on the deceleration of the vehicle should be taken into account. This task was first studied in Germany in 1968, when Marquard published values of two useful correction factors from forward calculations of 3 spins to rest. This landmark German study was extended in the United States in 1975, when McHenry fitted polynomials to the values of five correction factors computed for 18 spins simulated with the just-completed SMAC program. These polynomials were used within the computerized reconstruction program CRASH. However, the individual data points were never published; and since 1975, no further quantitative treatment of post-spin reconstruction has been published. Further studies now have been performed using a verified proprietary version of SMAC, for the same family of 18 spins.

The type of differential used in a vehicle has an important and often-neglected effect on handling performance. This is particularly important in racing applications, such as in IndyCar racing, in which the type of differential chosen depends on the course being raced (superspeedway ovals, short ovals, temporary street courses and permanent road courses). In the present work, we examine the effect of a locked rear differential on oversteer/understeer behavior. Using a linear tire model, it is shown that employing a locked differential adds a constant understeer offset to the steering wheel angle (SWA) -v- lateral acceleration vehicle signature. A computer simulation of steady-state cornering behavior showed that the actual effect is much more complicated, and is strongly influenced by static weight distribution, front/rear roll couple distribution, available traction and the radius of the turn being negotiated.

Roadway tractive capabilities are an important factor in accident reconstruction. In the absence of full-scale experiments, tire/road coefficient of friction values are sometimes quoted from reference textbooks. For the various types of road construction, the values are given only in the form of a wide range. One common roadway type is oil-and-chip construction. We examine stopping distances for newly-rocked oil-and-chip roads vs. similarly constructed roads that have been traffic-polished. The examination was conducted through full-scale braking experiments with instrumented vehicles. Results show that the differences between newly-rocked oil-and-chip roads when compared to roads that are traffic-polished are on the same order as vehicle, tire and ABS algorithm differences, and that full-scale testing is required for accurate μ-values.

The relatively fragile nature of racing tires, coupled with the inevitable track debris which results from racing accidents, ensures that racing drivers will routinely experience conditions involving flat tire vehicle dynamics. We define flat tire vehicle dynamics as a situation which requires the driver to provide steering and/or braking and acceleration control while the vehicle is running on one or more tires which have dramatically reduced tire pressure. In the present work, we simulate the handling and braking vehicle dynamics which occur in the presence of a single flat tire on the vehicle. The flat tire was simulated via drastically reduced cornering stiffness, partially reduced limiting frictional capability and increased rolling resistance, and was alternatively simulated on both the front and rear axle. No simulations were conducted with more than a single flat tire because multiple tire failures which do not involve an actual accident contact and/or damage are rare.

Off road vehicle dynamics present fundamental differences to the engineer than those of highway vehicles. In this work, we examine off-road dynamics for a class of industrial vehicles: front-end loaders. After a review of terramechanics and off-road tire behavior, equations of motion for a front-end loader are developed. Kinematic steering relationships, steady-state performance and understeer and oversteer characteristics are also derived. Off-road front-end loader characteristics and performance in terms of vehicle handling, overturn behavior and obstacle avoidance are presented, and some design characteristics and parameter values for a typical vehicle are given to aid the designer in analysis and synthesis.

Four wheel steering (4WS) of passenger cars has become a topic of interest in recent vehicle dynamics literature. In the present work, a linear two-degree of freedom model (L2DF) has been used to examine controllability and stability aspects of various 4WS algorithms. Yaw rate r and lateral velocity v were used as model degrees of freedom, and as state feedback variables for the implementation of 4WS controllers of various types. With controllers developed using the L2DF model, investigations were performed into the performance of such controllers when implemented using a nonlinear three-degree of freedom model (N3DF) which included roll and the possibility of tire saturation. Desirable steady-state properties for v and r can be obtained using the robust controllers developed through the use of the L2DF model. Finally, the stability of the system is shown to depend upon tire cornering stiffness, and is examined both qualitatively and quantitatively.

The ability to categorize, compare and segregate the roll dynamical behavior of various vehicles from one another is a subject of considerable research interest. A number of comparison paradigms have been developed (static stability index, roll couple methods, etc.), but all suffer from lack of robustness: results developed on the basis of a particular comparison metric are often not able to be generalized across vehicle lines and types, etc., or they simply do not segregate vehicles at all. In addition, most models do not describe vehicle dynamics in sufficient detail, and some contain no dynamics at all (e.g., static stability index = t/2h). In the present work, static stability index, a two-degree-of-freedom roll model and a three-degree-of-freedom roll and handling model were used to locate eigenvalues for a sample of 43 vehicles consisting of (1) passenger cars, (2) light trucks, (3) sport/utility vehicles and (4) minivans.

Open-wheel dirt-track racing represents one of the most dangerous forms of motor racing. The potential for touching and/or interlocking of rotating wheels, combined with the frangible and rutted nature of the track surface itself, makes the occurrence of x-axis [8] rollovers routine. In addition, the rollovers themselves are usually at a high enough speed so that very violent dynamics and occupant accelerations occur. The accelerative vectors present an unusual set of challenges to the restraint systems employed. In this work, we examine a single dirt-track rollover event.

During the month of May, 1994, there were a total of 15 accidents at the Indianapolis Motor Speedway (IMS). Of this total, six accidents occurred during practice and/or Qualifications Attempts and nine occurred during the 78th running of the Indianapolis 500-Mile Race. All six practice accidents were analyzed through the use of videography, skidmark measurements, photographs, angle of wall impact (if a wall impact occurred), vehicle damage and yaw angle measurements. The accidents were categorized according to type and severity, mechanical failure or driver error, speed at the initiation of the accident sequence, driver injury (if injuries occurred), weather, track and traffic conditions. Race accidents were also analyzed. The study represents the continuation of a long-term program to catalog, analyze and reconstruct accidents at IMS.

A. brief survey of vehicle dynamics and aerodynamics papers pertinent to open wheeled racing cars is presented. In this work, the aerodynamics of Indy cars have been studied from both a lift and drag point of view. A standardized definition of lifting area for ground effects vehicles and performance observations made through the use of radar and track simulations were used. Values for negative lift magnitude were determined, lifting area was photogrammetrically measured, and a lift coefficient appropriate for Indy cars was developed. Drag area, also obtained photogrammetrically, and drag coefficients were developed. Mechanical measurements of vehicles and wind tunnel experiments were used to estimate total drag and subsequent values for drag coefficients. These values correspond with energy balance calculations based on available engine power. A sensitivity study of the performance parameters of Indy cars was performed, with emphasis on enhancing top speed.