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Deteriorated roadway surfaces (potholes) encountered under everyday driving conditions may produce external vehicle disturbance inputs that are both destabilizing and highly transient. We examine vehicle behavior in response to such inputs through simulation. Idealized pothole geometry configurations are used to represent deteriorated roadway surfaces, and as environments in the HVE simulation suite of programs. Differences in vehicle response and behavior are cataloged, and the potential for destabilized vehicle behavior is examined, particularly under conditions in which only one side of the vehicle contracts the pothole. Vehicle types used in the simulation ensemble represent three classes of vehicles: a sedan, a sports car and an SUV. Results show that many combinations of vehicle speed, vehicle type and pothole configuration have essentially no destabilizing effects on the vehicle trajectory.

Various mechanical and electromechanical configurations have been proposed for the recapture of vehicle kinetic energy during deceleration. For example, in Formula One racing, a KERS (Kinetic Energy Recovery System) was mandated by the FIA for each racing car during the 2011 World Championship season and beyond, and many passenger car manufacturers are examining the potential for implementation of such systems or have already done so. In this work, we examine the potential energy savings benefits available with a KERS, as well as a few design considerations. Some sample calculations are provided to illustrate the concepts.

Vehicles running in wet conditions may experience hydroplaning of one or more tires. Hydroplaning can, and often does, change vehicle braking, acceleration and handling characteristics dramatically. Proper analysis of this behavior requires accommodating the clearing of paths for the rear tires that may result from the front tires engaging the water-coated surface first. In this work, tire overlap is calculated for vehicles in steady-state cornering maneuvers for generalized vehicle dimensions and tire characteristics.

Recent research on the effects of tire hydroplaning has examined the hydroplaning phenomenon and its potential effects on vehicle maneuvering from (1) geometric, (2) straight line braking/acceleration and (3) steady-state cornering maneuver points of view. In this work, we focus on the potential for hydroplaning during a transient maneuver: a standardized double lane change maneuver (ISO3888-1). Using both closed-form calculations and the HVE software suite, it is shown that partial hydroplaning has only a small-to- moderate potential to occur during portions of such maneuvers, but is not likely throughout the entire duration of the maneuver.

Vehicles running in wet conditions may experience hydroplaning of one or more tires. Hydroplaning can, and often does, change vehicle braking, acceleration and handling characteristics dramatically. Proper analysis of this behavior requires accommodating the clearing of paths for the rear tires that may result from the front tires engaging the water-coated surface first. In this work, a hydroplaning analysis is presented that examines steady-state cornering under potential hydroplaning situations and includes lateral weight transfer, tire load sensitivity and path clearing potential. The sensitivity of vehicle understeer/oversteer characteristics to path clearing and vehicle dimensional characteristics is also examined.

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

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!

The current performance of a top fuel (T/F) dragster racing car is very high. The cars can accelerate from a standing start to well over 330 mph (528 km/h) in < 4.6 seconds! The engine of a T/F dragster can make considerably more power than can be put down to the track surface. Intentional clutch slippage prevents wheelspin for most of the ¼-mile (0.4 km) standard length racing run. Even though the drive tires used are highly specialized and specifically designed for this type of racing environment, more traction is needed. To create more traction, especially during the second ½ of the run, external wings have been employed by the designers of such cars. The size and configuration of the wings is limited according to sanctioning rules. Recent wing failures and accidents have made other options for the creation of downforce appear attractive. In the present work, we consider the potential for using the shape of the car itself to create the required down-force.

The various forms of professional and amateur motor sports all require barriers, fences and deceleration/run-off areas for driver and spectator safety. We examine the translational and rotational kinetic energies involved for various types of race vehicles, and present some comparisons to typical energies encountered in everyday situations. Stopping distance vs. deceleration rates are also calculated, and some simplified trajectory analyses are performed for parts potentially launched during racing accidents.

Enthusiasts, accident reconstructionists and racing personnel have always been interested in wheel torque and HP values for vehicles. Modifications to the engine and/or driveline cause factory data to be in error, and special racing engines have no such data available in any case. Engine dynamometers provide useful information, but require the engine to be removed from the car before any testing can occur. Of more interest, particularly in competition situations, is the effect of changes at the driving wheels. We focus here on a simple method of deriving rim torque and HP values from accelerometer data. The data can be acquired using nearly any sufficiently accurate accelerometer package, and the calculations involved can be done by hand or with a spreadsheet program. Unknown vehicle characteristics can be extracted from coastdown tests. Use of a chassis dynamometer is not required.

In the scientific design of racing facilities and cars, a strong interplay exists between the aerodynamic characteristics permitted by the vehicle formula and the banking present at each track. We explore this relationship and in particular the sensitivity of various car and track combinations to changes in nominal values for banking and aerodynamic performance. Specific example calculations for NASCAR and IRL/CART vehicles and tracks are given.

Off-road excursions are common in road racing. Current circuit design practice attempts to control off-road vehicle motion and speed with a combination of gravel traps and barriers. Low gravel trap deceleration rates, coupled with wide variation in vehicle attitude during such excursions, produce an unsatisfactory and unacceptable vehicle response. Barriers and walls, while more effective at creating high deceleration rates, can also produce unpredictable response, and often generate vehicle damage and driver injury when contacted, especially in road racing situations. We focus here on car control methods associated more with the vehicle than with the circuit. A new device, the Vehicle Arrester™, has been developed. Calculations and some experimental results indicate that the device could be extremely effective in producing high deceleration rates and a controlled vehicle heading during an excursion.

Traditional vehicle simulations use two methods of modeling driver inputs, such as steering and braking. These methods are broadly categorized as “Open Loop” and “Closed Loop”. Open loop methods are most common and use tables of driver inputs vs time. Closed loop methods employ a mathematical model of the driving task and some method of defining an attempted path for the vehicle to follow. Closed loop methods have a significant advantage over open loop methods in that they do not require a trial-and-error approach normally required by open loop methods to achieve the desired vehicle path. As a result, closed loop methods may result in significant time savings and associated user productivity. Historically, however, closed loop methods have had two drawbacks: First, they require user inputs that are non-intuitive and difficult to determine. Second, closed loop methods often have stability problems.

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.

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.

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.

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.

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.

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.

The mass moments of inertia of 44 mounted and unmounted passenger, racing and motorcycle tires were measured about the spin axis. In addition, for some of the unmounted tires, mass moment of inertia about an axis perpendicular to the spin axis was also measured. Simplistic models for calculation of tire mass moment of inertia were developed, and may be adequate if only approximate results are required. Following measurement of inertias using a torsional pendulum technique, linear correlation of inertia values with tire weight and diameter was performed. A simple pair of linear correlation equations (one for mounted tires, one for unmounted tires) gives highly accurate values for mass moment of inertia about the tire spin axis. Finally, a rule of thumb expression for estimating moment of inertia about a vertical axis was also developed.