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Evaluation of vehicle impacts may involve the use of computer simulations. While simulation programs with two-dimensional impact models have been used for decades, more recent three-dimensional impact models have been developed. This research compares DyMESH, the three-dimensional vehicle impact model in HVE-SIMON, with full-scale vehicle crash tests involving low-speed rear impacts. Exponent Failure Analysis Associates (Phoenix, Arizona) conducted rear impact research involving two virtually identical 1983 Nissan Pulsar NX 2-door vehicles. One vehicle was stationary, while the second vehicle impacted the rear of the first vehicle in an aligned configuration. Tests were run at impact speeds ranging from 5 to 20 MPH. Tri-axial accelerometers were positioned in both vehicles and vehicle acceleration and velocity responses were recorded. SIMON-DyMESH was used to simulate these impact tests. DyMESH utilizes a mesh shell determined by the three-dimensional geometry of the vehicle.

CARAT (Computer Aided Reconstruction of Accidents in Traffic) is a Microsoft Windows® based simulation program. CARAT allows for simulation of pre-collision, collision, and post-collision dynamics in a graphical environment. CARAT can model cars, trucks, trailers and tractor/semi-trailers. CARAT-3, released in the mid-90's, is a three degree-of-freedom (3 DOF) model, with three dependent DOF, and operates mathematically in a two-dimensional (2D) graphical environment. Vehicle graphics can be viewed in three dimensions (3D). CARAT-4 implements 3D multi-body models with 10 DOF for the car model, and up to 26 DOF for the truck and trailer model. CARAT is a time forward kinetic simulation, but can also be used to perform kinematic calculations forward and backwards in time. Both CARAT-3 and CARAT-4 implement a momentum-based collision algorithm.