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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.

In the present work, we study motorcycle dynamics under conditions where the motorcycle-rider combination encounters either a step or a channel parallel to the direction of travel. Analyses are presented from the points of view of geometric, analytical and experimental approaches. As with passenger cars and trucks which encounter so-called “edge drop-offs,” the results depend on the magnitude and shape of the step or channel, velocity of the motorcycle and control input(s) of the rider, if any. Results show than for many common disturbance situations, difficulties may be experienced by the rider.

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.

An experimental program to measure braking characteristics developed under emergency braking conditions by ABS-equipped vehicles was designed and performed. Variables examined included initial braking speed, vehicle type, tire pressure and data recording equipment utilized. All experiments were conducted on a closed airport taxiway constructed of sharp, brushed and heavily striated concrete. Tests were conducted with and without activated ABS systems on the test vehicles. Results showed that (1) with the ABS activated, faint roadway markings were visible only under a very few special circumstances, (2) tire/road μ-values and corresponding deceleration values varied only slightly for differing speeds and ABS conditions, (3) tire pressure made little difference in limited test results, and (4) there were differences in recorded results depending on the equipment used for data acquisition.

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.

Speed trials have been conducted on the Bonneville Salt Flats for more than 50 years. In many ways, land speed racing represents the ultimate in freedom, ingenuity and creativity for engineers and constructors. Most of the rules associated with the various classes (and there are literally hundreds of classes) are safety-related, while the rules associated with the design and construction of the vehicle itself are extremely free, with streamliner and lakester classes being the most uninhibited of all. This freedom of design leads to widely disparate attempts to solve the Bonneville riddle. To successfully race at Bonneville requires the engineer to possess expertise in a number of aspects of vehicle design and construction rarely seen in other forms of racing competition. We begin with an overview of the nature of land speed racing competition, and continue to a discussion of the engineering aspects and fundamental requirements of car design and behavior.

During wet weather operating conditions, tire hydroplaning can occur, potentially altering the handling characteristics of a vehicle. The rear tires of the vehicle run in a path previously cleared by the front tires under some operating conditions. Although path clearing has been previously demonstrated both analytically and qualitatively, it is difficult to estimate the changes in the tire/road coefficient of friction resulting from path clearing because of the complexity of the hydroplaning flow regime. In the present work, we utilize wheelspeed information captured from the vehicle CAN bus and photography to examine potential variations in tire/road coefficient of friction that result from path clearing. Results suggest that differences in friction availability may result from such path clearing. Maneuvers performed include steady-state cornering tests, straight-line braking and ISO lane change maneuvers.

This research compares the responses of a vehicle modeled in the 3D vehicle simulation program SIMON in the HVE simulation operating system against instrumented responses of a 3-axle tractor, 2-axle semi-trailer combination. The instrumented tests were previously described in SAE 2001-01-0139 and SAE 2003-01-1324 as part of a continuous research effort in the area of vehicle dynamics undertaken at the Vehicle Research and Test Center (VRTC). The vehicle inertial and mechanical parameters were measured at the University of Michigan Transportation Research Institute (UMTRI). The tire data was provided by Smithers Scientific Services, Inc. and UMTRI. The series of tests discussed herein compares the modeled and instrumented vehicle responses during quasi-steady state, steady state and transient handling maneuvers, producing lateral accelerations ranging nominally from 0.05 to 0.5 G's.

Vehicles operating in wet conditions may experience hydroplaning of one or more tires. 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. An experimental program was developed to study tire/road behavior during straight line braking maneuvers on a wet surface. Wheel rpm values were measured with operating ABS via CAN bus data. The experiments allowed qualitative estimation and visualization of the effects of path clearing on rear tires.

Many modern vehicles utilize so-called “space-saver” spare tires. Such tires are not fitted to the vehicle and driven on until a tire problem has arisen with a service tire, and are limited in the mileage and speed at which they can operate. They also may have quite different characteristics (rolling radius, tread pattern, contact patch width and length, aspect ratio, stiffnesses, self-aligning torques, etc.) than the service tires with which the vehicle is equipped. As such, they have the potential for presenting significantly different handling signatures to the driver when they are fitted.. In the present work, we present force and moment characteristics for two disparate space-saver spare tires. The tires were tested at the T.I.R.F. (TIre Research Facility), Calspan Corporation, Buffalo, NY.

Many vehicles are equipped with independent suspension systems on the front and/or rear axle. As opposed to a DeDion or beam axle, independent suspension systems have the potential to generate camber and toe changes as the suspension strokes from full jounce to full rebound. Each vehicle suspension design presents unique camber and toe curves to the tire. To improve handling, manufacturers often set static camber on such vehicle suspension systems to nonzero values so that when cornering, the outside suspension will deflect so as to maximize cornering power and vehicle stability. Then, under straight driving conditions, the tires tend to predominantly wear their inside shoulder edges, producing the phenomenon known as camber wear.

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.

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.

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.

We examine the characteristics, properties and potential idealized delamination failure modes of tires in this work. Calculations regarding tire failure stresses during tire failure scenarios, as well as during normal operation, are made. The calculations, though idealized, indicate that large chassis loads can result from the idealized failures.

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.

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.

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.

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!