Crashworthiness optimization of civil aircraft subfloor structure

For a typical civil aircraft fuselage structural crashworthiness design with several design parameters, a design approach is proposed to minimize the peak acceleration of the cabin floor and maximize the internal energy of the structure at a certain crushing state. A Kriging surrogate model is adopted for impact response approximation, a nondominated sorting genetic algorithm II (NSGA-II) for dual objective optimization, and Nash-Pareto strategy for the optimum design selection. In order to obtain the effect of design parameters on crashworthiness as well as the optimum design, a synchronous sampling criterion of the maximum expected improvement and the maximum predicted variance is suggested to construct a surrogate model. Using this design approach, a typical civil aircraft fuselage structural design with the shape parameters of the cabin floor struts, cargo floor and foam components is studied as a design case. The results indicate that the peak acceleration of the cabin floor is reduced by about 18.3% as compared with the original design; the second-highest peak acceleration is also reduced. Consequently, the crashworthiness of the fuselage structure is improved. The error between the predicted responses of Kriging model and the analysis results of the finite element method is less than 1%, which illustrates the effectiveness of this design approach.