Analytical Model for Investigating Low-Speed Sideswipe Collisions
Dr. James R. Funk, Mr. Joseph M. Cormier, Dr. C.E. “Ted” Bain
Accident Reconstruction 2004 (SP-1873). Warrendale, PA, Society of Automotive Engineers, Inc. 2004; 23-34. SAE Paper #2004-01-1185.
Vehicle dynamics in sideswipe collisions are markedly different from other types of collisions. Sideswipe collisions are characterized by prolonged sliding contact, often with very little structural deformation. An analytical model was developed to investigate the vehicle dynamics of sideswipe collisions. The vehicles were modeled as rigid bodies, and lateral interaction between the vehicles was modeled with a linear elastic spring. This linear spring was meant to represent the combined lateral stiffness of both vehicles before significant crush develops. Longitudinal interaction between the vehicles was modeled as frictional contact. In order to validate the model, seven (7) low-speed (3 - 10 kph), shallow angle (15ş) sideswipe collisions were staged with instrumented vehicles. These sideswipe collisions were characterized by long contact durations (~ 1 s) and low accelerations (< 0.4 g's). The experimental collisions were also simulated with EDSMAC. EDSMAC overpredicted peak longitudinal vehicle acceleration by an average of 83% and underpredicted the length of contact damage by an average of 50%. In contrast, the linear spring model accurately predicted the peak longitudinal vehicle acceleration (5% error) when the stiffness parameter was tuned to match the length of contact damage. These results suggest that a noncrush-based linear spring model for calculating intervehicular force could significantly improve the accuracy of reconstructions of low-speed sideswipe collisions compared to existing methods such as SMAC.
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