Crashworthiness analysis and optimization of bionic corrugated sandwich structures

Abstract

To improve the crashworthiness of thin-walled sandwich structures, a series of bionic corrugated sandwich structures with triangular elements (the height-to-width ratios of the elements are defined as γ) were designed inspired by the structures of shrimp chelas, including single-layer, double-layer and three-layer corrugated sandwich structures (γ1, γ2 and γ3 denotes the height-to-width ratios of single-layer, double-layer and three-layer elements, respectively). To analyze the deformation and mechanical response of the bionic thin-walled structures, the finite element method was adopted based on LS-DYNA and HyperMesh. By taking the initial peak load Fp and specific energy absorption Es as crashworthiness indexes, the influences of γ on the crashworthiness of the corrugated sandwich structures were discussed. The crashworthiness of the single-layer sandwich structures becomes worse gradually when the parameters γ exceed a certain value. For the double-layer sandwich structures, the influences of the parameters γ2 in the lower layers on the crashworthiness is greater than that of the parameters γ1 in the upper layers.. The Fp decreases by 37.8% with the increase of γ2, which means the greater γ2 of the lower layer is beneficial to improve the crashworthiness of the structure. For the three-layer sandwich structures, the influence of γ on crashworthiness indexes was investigated by range and variance analysis methods. The results show that the γ3 has the most significant influence on Es, and the significance level reaches 0.1. Finally, the optimal parameters of the bionic corrugated sandwich structures were obtained by using the multi-objective particle swarm optimization method based on a polynomial regression (PR) meta model. The optimal results show that the crashworthiness of the single-layer corrugated sandwich structures improves with the increase of γ. For the double-layer corrugated sandwich structures, The γ of the lower layer affects the crashworthiness more significantly than the γ of the upper layer. The three-layer corrugated sandwich structure with lower γ has higher Es. The optimal dimensions of the single-layer, double-layer and three-layer structures are γ = 0.8; γ1 = 0.5 and γ2 = 1.2; γ1 = 0.6, γ2 = 0.6 and γ3 = 0.9, respectively. The above results are helpful for the design of the thin-walled sandwich structures.