A comparative study of design optimisation methodologies for side-impact crashworthiness, using injury-based versus energy-based criterion

The tension between occupant safety during a crash and lightweight designs continues to be an important driver of modern vehicle designs. While occupant safety may be defined and evaluated in various ways, maximising energy absorption of structural components during impact has been adopted for vehicle designs by many manufacturers. An alternative method to evaluate safety but often not directly used in the design of structural components is the use of a dummy model in the finite element (FE) simulation to estimate the forces and accelerations that would be experienced by a human in a crash environment. This paper investigates the similarities/differences between designing vehicular structural components experiencing side impacts based upon two different criteria: (1) the energy absorption of collapsed components in the absence of a dummy and (2) an injury metric–based approach with the responses of the dummy as the bases. Multi-objective optimisation methods are used with finite element analysis (FEA) in the lightweight design for side-impact crashworthiness, considering the two different criterion. The results show that the optimum designs based on the two criteria are significantly different and that the injury-based approach should be incorporated into vehicular lightweight design process when considering crashworthiness.