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An easy-to-use computer program for ride analysis was recently developed. The result of this effort-RideSim- predicts time history responses, power spectral density (PSD) functions, and a driver oriented measure of ride comfort. RideSim employs a graphical user interface (called SGUI, for simulation graphical user interface) to control data preparation, simulation execution, animation, and data analysis. The SGUI allows the user to operate the program by pointing and clicking with a mouse, rather than by using cumbersome text commands. It also manages the vehicle dynamics parameters, the resulting simulation output, and results of post-processing analyses (i.e., PSD analysis). The vehicle dynamics model was generated with the AUTOSIM multibody dynamics program. This program uses Kane’s Method and computer algebra to create a parametric dynamics simulation that can be easily linked to the SGUI.

Due to the high incidence of rollover in the accident experience with Michigan double-bottom tankers, a special study of rollover dynamics was included in the ad hoc study of those vehicles at The University of Michigan. A dynamic model of the vehicle in the roll plane was formulated for study of roll motions under arbitrary lateral force input time histories. The roll response and limit manuever capabilities predicted by the model were compared against that of actual vehicles and good agreement was obtained. The model was used to predict the relative rollover thresholds of the double-bottom tanker and other alternative tanker configurations for comparison to that of other commercial vehicles in a selected double lane-change maneuver. The model confirmed that double-bottom tankers of the current design exhibit a low rollover threshold in comparison to other commercial vehicles; and that certain design changes proposed as a retrofit would effectively eliminate that disparity.