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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 Articulated Total Body (ATB) program has been used to study occupant kinematics in motor vehicle collisions for several years. The ATB model is a complex 3-dimensional lumped-mass model available for many different computer systems, including the personal computer, and requires formatted data files for the data input. A new version of this model, Graphical Articulated Total Body (GATB), has been developed to be operated under the HVE (Human, Vehicle, Environment) computer environment. The GATB program uses the graphical system built into HVE. This aids in set up and execution of the model to study human occupants in motor vehicle collisions. This paper addresses the integration of the ATB model with the HVE environment and includes a validation study comparing the GATB results to those of the ATB program.

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.

The Articulated Total Body (ATB) computer program, sometimes referred to as the Crash Victim Simulator (CVS), is a powerful tool to aid in studying occupant kinematics in motor vehicle collisions. There are many options available within the ATB/CVS model and associated utility programs, such as GEBOD, which allow an analyst to model specific collisions and occupants. This paper discusses ATB/CVS as a tool for use in collision reconstruction. Specific examples are presented in developing a crash pulse from vehicle simulation programs such as EDSMAC, SMAC, HVOSM, etc. Techniques are also presented for modelling other moveable objects within the occupant environment, such as a seat back, steering column, or intrusion into the occupant compartment. A series of programs to aid in setting up an ATB data file, the CAL-3D Users Convenience Package, is also discussed.

The time/distance relationship for a heavy truck accelerating from a stop is often needed to accurately assess the events leading up to a collision. Several series of tests were conducted to document the low speed acceleration performance of a 2016 Freightliner Cascadia truck tractor equipped with a 12-speed automated manual transmission in Auto Mode. Unlike tests in previous papers, the driver never manually shifted gears. These tests included three trailer load configurations and two different acceleration rates. Data were gathered with both a VBOX and with the Detroit Diesel Diagnostic Link (DDDL) software.

The time/distance relationship for a heavy truck accelerating from a stop is often needed to accurately assess the events leading up to a collision. Several series of tests were conducted to document the low speed acceleration performance of a 2016 Kenworth T680 truck tractor equipped with a ten-speed overdrive automated manual transmission in Auto Mode. Throughout the testing, the driver never manually shifted gears. This testing included three trailer load configurations and two different acceleration rates. Data were gathered with a VBOX and the Cummins INSITE software.

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