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Technical Paper

Computer Aids for Accident Investigation

Correlation of injury with the nature and severity of the acceleration exposure in actual highway accidents is complicated by problems with uniformity in the interpretation of accident evidence. ...Through the use of such aids in accident studies, it is possible to establish injury thresholds and mechanisms for living humans in relatively detailed exposures and under different conditions of restraint and protection.
Technical Paper

Computer Program for Reconstruction of Highway Accidents

In one of the presented applications to a staged collision, the initial conditions were kept unknown until completion of the reconstruction process. Results of sample applications to actual highway accidents are included. ...The Simulation Model of Automobile Collisions (SMAC) computer program has been developed for the purpose of achieving uniformity in the use of analytical techniques for interpretation of physical evidence in investigations of highway accidents. The comprehensive output information of the SMAC program (kinematics, tire tracks, and vehicle damage) permits extensive, detailed comparisons with physical evidence in the iterative runs used to achieve a “best fit,” and the predicted vehicle responses provide a basis for relatively refined categorization of occupant exposures. ...Computer graphics displays of reconstructed accidents, including rest positions, tracks, and damage, are presented.
Technical Paper

A Comparison of Results Obtained With Different Analytical Techniques for Reconstruction of Highway Accidents

For several staged collisions, results obtained with closed form reconstruction calculations and with a computerized step-by-step procedure are compared with measured responses. ...A refined, closed-form reconstruction procedure is defined, derivations of the analytical relationships are outlined and detailed results of sample applications are presented. ...Since a high degree of success was achieved in the refinement of such calculation procedures, the end product, by itself, is considered to be a valuable aid to accident investigations.
Technical Paper

Computer Simulation of Single Vehicle Accidents

However, the developed computer simulation also has potential applications in the reconstruction of single vehicle accidents and in studies of the driving task at the upper limits of vehicle control. ...The results of a review of single vehicle accident statistics and measurements of structural load-deformation properties of automobiles, performed within this research program, are both presented.
Technical Paper

RICSAC-97 A Reevaluation of the Reference Set of Full Scale Crash Tests

Previous research using the RICSAC test results, particularly in relation to the validation of accident reconstruction computer programs, has varied widely in acceptance, interpretation and presentation of the RICSAC test results. ...A discussion of previous research which included reference to the RICSAC test results as a measure of the validity of reconstruction computer programs is included.
Technical Paper


The rationale for a continued interest in the SMAC approach to reconstruction is discussed. Modifications and refinements that have contributed to the current capabilities of SMAC-87 are briefly described, representative results of applications are presented and planned future developments are defined.
Technical Paper

SMAC2003: The Automatic Iteration of SMAC

In prior studies researchers have been interested in automating the process by which the Simulation Model of Automobile Collisions (SMAC) is used to reconstruct an accident. The SMAC program requires an initial approximation of the impact speeds and the positions and orientations at impact. ...And with a SMAC reconstruction you can sometimes get a reasonably close match and then spend many hours on iterative runs trying to match as best as possible the overall body of physical evidence.
Technical Paper

SMAC-97 Refinement of the Collision Algorithm

The effects of the modifications of the SMAC algorithm on reconstruction results are presented in the form of direct comparisons of results obtained with the original and modified algorithms.
Technical Paper

Effects of Restitution in the Application of Crush Coefficients

The effects of the refinements to the damage analysis procedures on reconstruction results are illustrated by direct comparisons with corresponding results produced by the original SMAC and CRASH programs and with measured data from full scale vehicle impact tests.
Technical Paper

The Astro Spiral Jump-An Automobile Stunt Designed via Computer Simulation

An unusual application of a computer simulation of automobile dynamics to the design of a thrill show stunt is described. The rationale for development of the simulation for highway safety applications is discussed and the general analytical approach is described. Computer graphics displays of simulation outputs, consisting of detailed perspective drawings of the vehicle and terrain features or obstacles at selected intervals of time during a simulated maneuver, are presented. For the presentation of the paper, computer graphics displays of simulation outputs will be animated through the use of motion picture film. Also, motion picture coverage of both developmental tests and public performances of the Astro Spiral Jump will be shown.
Technical Paper


A brief description and history of the Highway Vehicle Obstacle Simulation Model (HVOSM) computer program is presented. A number of references are cited that include applications of HVOSM and which present detailed descriptions of related extensions and refinements. This paper focuses attention on simulation developments of HVOSM and validation efforts specifically related to the simulation of collisions with concrete median barriers (CMB).
Technical Paper

A Revised Damage Analysis Procedure for the CRASH Computer Program

A revised damage analysis procedure for CRASH, which includes restitution effects, is described. The proposed calculation procedure has the potential capability of (1) improving the delta-V accuracy in low-speed collisions and (2) segregating stiffness and restitution properties. The analytical approach can provide a basis for refinement of the categorization of vehicles through its use of additional crush property descriptors. Sample results from applications of a prototype computer routine are presented and compared with corresponding results from the original damage routine of CRASH. The reported research has been supported by McHenry Consultants, Inc.
Technical Paper

Research in Automobile Dynamics - A Computer Simulation of General Three-Dimensional Motions

A digital computer simulation of complex, three-dimensional dynamics of automobiles on irregular terrain is described which is suitable for studies related to vehicle braking systems and to the driving task, including the upper limits of control as well as the linear ranges of operation. The reported simulation is an extended version of an earlier, validated mathematical model. A number of refinements and extensions of the analytical treatments of tire forces, suspension properties, and terrain definitions, have been incorporated. Also, analytical representations of the braking system and driveline, and approximations of rolling resistance and aerodynamic drag, have been introduced. Sample outputs of the modified computer program are presented and discussed.
Technical Paper

Computer Simulation of the Crash Victim - A Validation Study

A program of research was conducted to examine the validity of a digital computer simulation of an automobile occupant during a frontal, head-on collision. The simulation is designed to permit a detailed study of the effects of several types of restraint systems on occupant responses in a confined compartment, where injury-producing contact forces occur. The effects on occupant responses produced by the positions, orientations, and load-deflection properties of contacted interior surfaces are also simulated. This progress report covers one phase of a CAL long-range program of development of simulation techniques for study of occupant/vehicle and vehicle/obstacle collision responses. Detailed comparisons are presented of responses from instrumented sled tests and corresponding computed responses from the simulation. The comparisons include forces in restraint belts and on contacted surfaces, accelerations of the dummy, and the detailed kinematics of the dummy itself.