In addition, the first three fundamental natural frequencies are combined with the crash
metrics to form the design constraints. The wall thicknesses of twenty-two parts are considered as the design variables. Latin Hypercube
Sampling is used to sample the design space, while Radial Basis Function methodology is used to develop surrogate models for the selected
crash responses at multiple sites as well as the first three fundamental natural frequencies. A nonlinear surrogate-based optimization problem is
formulated for mass minimization under crash and vibration constraints