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Technical Paper

Analysis of a Dirt Track Sprint Car Accident

The purposes of the investigation were (a) to attempt to characterize the dynamics of the vehicle motion through videographic analysis, (b) to estimate the accelerative loadings to which the driver would be exposed, (c) to develop a first order analysis model for car and suspension motions which ensue following interlocking of counterrotating wheels, and (d) to determine whether current restraint technology is acceptably strong enough to face such accidents. To begin, a short introductory section characterizing dirt-track midget car racing in general is presented. ...Dirt-track racing presents a very high potential for rollover accidents whenever a sprint car is presented sideways to its direction of travel. A short description of the accident event is presented next, followed by a discussion of the mechanism of tripped and untripped rollover. ...A short description of the accident event is presented next, followed by a discussion of the mechanism of tripped and untripped rollover.
Technical Paper

Skidmark Signatures of ABS-Equipped Passenger Cars

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. ...Under such circumstances, a number of accident reconstruction techniques based on skidmark length measurements have to be abandoned.
Technical Paper

Analysis of 1994 Indianapolis 500-Mile Race and Practice Accidents

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. ...The study represents the continuation of a long-term program to catalog, analyze and reconstruct accidents at IMS. Here, we present the second year of this serious effort at accident analysis, and introduce an increased level of rigor in categorization, data collection and data analysis. ...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.
Technical Paper

Post-Impact Spin, 1968-1993

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. ...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. ...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.
Technical Paper

Protection of Drivers and Spectators from Pit Entrance Injuries Incurred During Loss of Control Accidents

Although the single accident which occurred was a (relatively) low-speed accident, results were promising in view of what was expected. ...Through a video analysis and data acquired from timing devices imbedded in the track surface, the accident was reconstructed and the wall attenuation device performance was compared to expected results. ...Two types of wall contact can be considered, (a) a brush-by or wall sideswipe accident, in which the vehicle velocity vector is nearly parallel to the wall surface, and (b) an impact where the velocity vector is at a significant angle with respect to the wall (but still at an acute angle).
Technical Paper

Evasive Maneuver Capability Without and In the Presence of a Flat Tire

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. ...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. NASCAR vehicle and tire data were used throughout the simulations.
Technical Paper

Kinetic Energies Involved in Racing Facility Design

Stopping distance vs. deceleration rates are also calculated, and some simplified trajectory analyses are performed for parts potentially launched during racing accidents.
Technical Paper

Potential for a Ground-Effects Top Fuel Dragster

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.
Technical Paper

Controlled Braking Experiments with and without ABS

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.
Technical Paper

Modeling Cruise Control Initiated Wheelspin in Rear Wheel Drive Vehicles

There are driving situations in which a rear-wheel-drive vehicle, operating with an active closed-loop cruise control, can experience wheelspin and a subsequent oversteer/loss of control. The situations involve low-μ surfaces (ice), weather-related phenomenon (rear-wheel hydroplaning), slope-climbing or a combination of these external effects. Although traction control and stability control, depending on the sophistication of the system, can negate many of these situations, the active fleet contains many vehicles not equipped with these features. In the present work, we calculate the conditions under which cruise-control-initiated rear wheel spin can occur.
Technical Paper

Mathematical Analysis of Tire Delamination & Rupture Failures

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.
Technical Paper

Potential for Hydroplaning Behavior during Transient Maneuvers

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.
Technical Paper

The Simulation of Driver Inputs Using a Vehicle Driver Model

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.
Technical Paper

Passenger Car Handling Characteristics Associated with Space-Saver Spare Tires

Space-saver spare tires have become near-standard equipment in passenger cars, replacing full-size spares. The properties of space-saver spare tires (cornering stiffness, self-aligning torque, etc.) exhibit some differences when compared to standard size tires. We examine potential handling changes when a space-saver tire is installed on the vehicle by examining steady-state behavior, initial step steering response, and vehicle understeer gradient as functions of the mounting location of the space-saver tire (front or rear axle). Results show that space-saver spare tires perform well and are quite capable in low-ay, linear handling maneuvers.
Technical Paper

Calculating Tire Overlap during Steady-State Cornering Maneuvers

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.
Technical Paper

Experimental Measurements of the Effect of Path Clearing on Hydroplaning Behavior

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.
Technical Paper

Soft Walls for Racetrack Barriers through the Use of Slatted Wall Design: A Conceptual First Analysis

For a number of years, racetrack designers have been considering various designs for energy-absorbing or “soft” walls. Moving walls, water-filled barrels, tire walls and walls coated with various materials have all been suggested or employed to varying degrees of success. In this paper, a new concept involving a series of slats placed outward from the walls is outlined. First, fundamental requirements for a soft wall design are laid down. Then the development of the slatted wall is presented, along with a series of design variables able to be adjusted for particular applications. The slats have multiple modes of energy dissipation and absorption, and calculations show that the concept has good promise. Evaluation of various design alternatives can be largely done computationally, rather than experimentally, a great advantage given the expense of full-scale barrier testing.