Abstract
Keywords - Computer Simulation, Biomechanics, Rear Impact, Seat Collapse, Child Head Injury
Abstract - Many variables, each with a wide parameter range, influence the performance limits and occupant injury protection levels provided by a motor vehicle safety system. Full scale crash tests offer one means to study safety system performance, but such tests are expensive and only provide limited data related to the influencing variables or factors. Commercially available occupant computer simulation codes, in conjunction with efficient multi-variable analysis techniques like the 2-level factorial method, offer a cost-effective means for multi-variable evaluation of a given safety system. The current study uses a Articulated Total Body (ATB) computer code, with a high-low (i.e. 2-level) factorial method, to study multi-variable effects of motor vehicle adult occupied front seat system performance as it relates to child head injury potential (i.e. HIC) of rear seated children during rear impacts. Of primary interest is: whether or not a adult occupied front seat will collapse into a child seated behind, and; if front to rear contact is made, under what conditions will it result in head injury to the rear child. Variables studied included: non-linear seat strength; impact severity (i.e. speed change); front adult occupant size; rear child size; and 2 vehicle types. Front seat strength levels ranged from about 3.1 kN, for a typical single recliner seat, on up to about 14.7 kN for a commercially available belt-integrated seat design. Impact severity levels ranged from about 20-kph on up to 50-kph speed changes. Front adult sizes ranged from a small female (i.e. 50 kg) on up to a larger male of about 110 kg. Rear child sizes included a 3 year-old, seated in the built-in booster seat of a minivan, and a 6 year-old, seated in the rear bench seat of a 4 door sedan. Analysis of the 3 year-old child head injury potential was conducted prior to the running of sled-buck validation tests. Refinements were made to the non-linear front seat computer model for the study of the 6 year-old. Sled-buck tests were also run for this case. The predicted and test HIC curves compared well in each case. Finally, the child HIC data was plotted over a range of variables (i.e. front occupant weight versus rear impact severity) and the results were compared with data from actual accident cases to validate the analysis.