Search Results

The trajectory solution procedures of the original CRASH program included both the SPIN routine and an exploratory trajectory simulation option to approximate and refine the linear and angular velocities at separation. The resulting separation speeds were then used to determine the impact speeds by means of application of the principle of conservation of linear momentum. This paper presents a detailed review of the logic, rationale and limitations of the trajectory solution procedures of the original CRASH program and discusses a number of refinements including: incorporation of the principle of conservation of angular momentum, approximations of the effects of changes during collision in the positions and orientations of the two vehicles and of the effects of external forces and moments that act on the two-body system during the collision, and adaptations of optimization techniques for error reduction and convergence in iterative solutions.

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).

Research performed in the 1970's revealed significant limitations in the available documentation of vehicle crush information and trajectory spinout information. As a result a series of full-scale crash tests were performed which became known as the Research Input for Computer Simulation of Automobile Collisions (RICSAC) 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. This paper presents a detailed review and decipherment in useable form of the original 12 crash tests that were performed within the RICSAC program. A new method of analyzing accelerometer data from arbitrary sensor positions, on the basis of discrete measures of the vehicle responses rather than complete time-histories, is defined.

A brief description and history of the SMAC computer program, including its relationship to CRASH, is presented. 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.

The Simulation Model of Automobile Collisions (SMAC) computer program, developed in the early 1970's, includes a complex collision algorithm for monitoring, detecting and modeling the collision interactions of motor vehicles. A detailed review of some aspects of the logic, rationale and, in particular, limitations of the original SMAC collision algorithm is presented. This paper presents refinements in the definition of the collision interface, the definition of collision type, the vehicle proximity and collision detection logic, and the form of supplementary impulsive constraints on relative motions. 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.