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The time/distance relationship for heavy trucks starting from a stopped position is often needed to accurately assess the events leading up to a collision. A series of tests were conducted to document tractor/trailer low speed acceleration performance. The vehicles were instrumented with a DATRON speed sensor and engine RPM was also documented. This paper presents the data from these tests and discusses the acceleration profile of heavy trucks in general.

Scientific visualizations and computer animations are frequently presented to show the results of simulation models or the opinions of a reconstructionist. In these cases it is important to properly document the graphical images being presented. Proper documentation depends somewhat on the methodologies used to produce the images, but every scientific visualization, computer animation, and computer generated image should be documented sufficiently to allow others to duplicate the images. There are also some basic data that should accompany any computer generated images that will reveal the basis of the motion for all primary objects being depicted. This paper presents some basic definitions and outlines the data that is required to document scientific visualizations and computer animations.

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.

Computer animation and its use in the engineering/scientific community are in their infancy. As this visualization tool becomes more widely used and accepted, individual expectations may differ greatly regarding appropriate usage and documentation of an animation. This paper lays the foundation for establishing guidelines for documenting the data and techniques used in producing an animation. The many elements that make up an animation are discussed, along with their importance to the presentation. The ultimate goal, for using the proposed guideline, is to achieve consistency within the engineering / scientific community when evaluating an animation.

The Human Vehicle Environment (HVE) program, developed by Engineering Dynamics Corporation, combines the vehicle parameters, physics and graphics into a single computer system for use in analyzing motor vehicle collisions, handling issues, studying occupant motion, etc. One of the most valuable assets of the HVE program is the open architecture that allows easy access to the data and graphics capabilities from an independent computer program. Thus, virtually any program that can be recompiled on the Silicon Graphics system can be set up to utilize the HVE tools. HVE is written in two computer languages known as C and C++ pronounced (“C plus plus”), this aids in the graphics processing. Unfortunately, FORTRAN programs do not automatically interface with C or C++ programs. These programs must be modified to allow a two-way data path to and from HVE.

There are many collisions in which the “standard” analysis methods are not sufficient to complete an analysis. Many times the points of rest for the vehicles are not documented or the vehicles were “driven” to the points of rest. There are also cases in which one of the vehicles is repaired prior to being documented. In these cases, there is a method that can be used to establish the approximated speed change of the vehicles. This method involves using the crush profile of one of the vehicles and balancing the opposing forces across the crush profile to determine an equivalent crush depth on the undocumented vehicle. Using this “balanced forces” method requires a detailed crush profile of one of the vehicles and good stiffness data for both vehicles. The method is not as accurate as standard methods because of the unknowns, but does yield reasonable results for the speed change severity for the vehicles involved.

The time/distance relationship for a heavy truck starting from a stopped position is often needed to accurately assess the events leading up to a collision. A series of tests were conducted to document the low speed acceleration performance of a Freightliner FLD-120 tractor-truck. The tests including several load configurations and acceleration rates. The vehicle was instrumented with a DATRON speed sensor and the engine RPM was also documented. This paper presents data from these tests and discusses low speed acceleration profiles of heavy trucks