This paper describes a side impact crash simulation technique and optimisation process developed to select vehicle structural design, padding and airbag characteristics that provide the best protection for occupants of different size, gender and fragility in crashes of different type, direction and severity. This work is part of a collaborative research project between Australian car manufacturer Holden, Monash University Accident Research Centre and other partners with funding from a government research grant, to developed a design technique providing optimum protection to the Australian community involved in side impact crashes.
Multi-variable optimisation using a full vehicle side impact finite element model is not currently feasible as this approach would use an impractically high level of computer resources. Consequently, a unique and extremely efficient side impact crash simulation technique has been developed to support the design optimisation process. Created using MADYMO3D software, this simplified side impact model incorporates only those parts of the structure that influence components interacting with the occupant. Reduction in computational complexity was achieved by the partial de-coupling of the side impact event. A full vehicle finite element computer model, including test dummy was utilised to predict the structural response to side impact, and this response was used as input for the new, simplified optimisation model. The commercial optimisation package Isight was used to control the optimisation process. Validation was performed using data from vehicle side impact tests, side impact sled tests and full vehicle finite element computer model predictions.
Societal Harm1 has been used for the objective function. For each simulation, dummy injury responses were translated into injury risk via the use of Injury Assessment Functions, and then from injury risk into societal cost. During each iteration cycle, societal costs from simulations with different crash configurations and occupant types were weighted according to the crash frequency observed during field study, thereby giving the measure of total Harm for that given trial design. After iterating through the range of design variables, the best set of interior trim, restraint and structural parameters was selected to provide maximum community protection.