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Sudden tire deflation, or blow-out, is sometimes cited as the cause of a crash. Safety researchers have previously attempted to study the loss of vehicle control resulting from a blow-out with some success using computer simulation. However, the simplified models used in these studies did little to expose the true transient nature of the handling problem created by a blown tire. New developments in vehicle simulation technology have made possible the detailed analysis of transient vehicle behavior during and after a blow-out. This paper presents the results of an experimental blow-out study with a comparison to computer simulations. In the experiments, a vehicle was driven under steady state conditions and a blow-out was induced at the right rear tire. Various driver steering and braking inputs were attempted, and the vehicle response was recorded. These events were then simulated using EDVSM. A comparison between experimental and simulated results is presented.

The use of computer animation in the analysis of automobile collisions provides a reconstructionist the ability to ‘see’ an object from any perspective and visually depict its movement in three-dimensional space. Although many computer animation programs are currently available, none of these off-the-shelf software and hardware combinations are directed specifically at animating vehicle or occupant motion in conjunction with a collision. Many computer programs, specifically created for modeling vehicle or occupant motion, are available, but these typically do not create visual images with the detail offered in computer animation programs. Analysts can generate the data for computer animation by using collision simulation programs along with computer spreadsheets. Techniques for calculating the data required for computer animation are discussed in this paper.

Computer models used to study crashes require information to describe the vehicles. Information such as weight, length, wheelbase, tire locations, crush stiffness, tire parameters, etc. all require a reliable source. Usually the tire parameters are difficult to obtain. Analysts will routinely use default or “typical” values. In 1999, Engineering Dynamics Corp. (EDC) attempted to address this issue, with support from many in the field of crash reconstruction, by conducting tire tests. The resulting tire test data will be used to study motor vehicle performance. The computer simulations in use today require information about tire properties or lookup tables that must be extracted from raw collected data. This paper presents a basic overview of the tire test data and a technique for extracting the required tire parameters for use in computer simulation modeling.

Rollover collisions sometimes involve a vehicle sliding and plowing on a soft-soil surface. There is little work published on the deceleration rates for a vehicle sliding and plowing in soft soil. Previous tests involving a 4-door sedan sliding sideways and plowing on a soft-soil surface were modeled using the HVE and SIMON 3-dimensional computer simulation program. The plowing forces were modeled using a series of friction multipliers. In addition, an SUV was simulated crossing the same surface in a similar fashion. Results based on these analyzed tests indicate that the average deceleration rate for either vehicle sliding sideways on this soft-soil surface may be approximated by using the vehicle’s static stability factor, or T/2H. This paper presents computer modeling techniques used to analyze overturn crashes. Specifically the SIMON 3-dimensional computer simulation model is used in this work.

Computer simulations are frequently used to analyze occupant kinematics in motor vehicle crashes, including what they collide with during the crash and the severity of these internal collisions. From study of such occupant simulations, it is then possible to infer how the actual human occupants may have been injured in a crash. When using a simulation to study how occupants react in a vehicle crash, a crash-pulse is usually required as input to the occupant simulation model. This crash-pulse is typically generated from a study of the vehicle motion and acceleration during the crash. There are several different methods for obtaining such a crash-pulse which are in common use. Each of these methods produces a different shape for the crash-pulse, even with identical velocity changes for the vehicle. The time duration, maximum acceleration, and general shape of the crash-pulse may influence the predicted motion of the occupants.