This study uses numerical design optimization with advanced metamodeling techniques to investigate the effects of material substitution and dummy models on crashworthiness characteristics of automotive structures. A full-scale Dodge Neon LS-DYNA finite element model is used in all structural analysis and optimization calculations. Optimization is performed using vehicle-based responses for multiple crash scenarios and occupant-based responses for one crash scenario. An AZ31 magnesium alloy is substituted for the baseline steel in twenty-two vehicle parts. Five base metamodels and an Optimized Ensemble metamodel are used to develop global surrogate models of crash-induced responses. Magnesium alloy is found to maintain or improve vehicle crashworthiness with an approximate 50% reduction in selected part mass using vehicle-based responses while dummy-based designs show less percentage decrease in weight. Vehicle-based responses selected to approximate dummy injury metrics do not show the same relative change compared to dummy-based responses
