仿生波纹夹层结构耐撞性分析及优化

为提高薄壁夹层结构耐撞性，以虾螯为仿生原型，设计梯度分布的仿生波纹形夹层结构，包括单层、双层和三层波纹结构。以初始峰值载荷F_p、比吸能E_s为耐撞性指标，利用有限元法分析了单元高宽比γ（γ₁、γ₂和γ₃分别为单元第1层、第2层和第3层的高宽比）对波纹夹层结构耐撞性的影响，采用多目标粒子群优化方法得到了夹层结构最优参数。结果表明，单层波纹结构耐撞性随单元高宽比γ的增大逐渐变差，双层波纹结构下层结构单元高宽比γ对耐撞性的影响大于上层结构单元高宽比γ对耐撞性的影响，较小的γ值有利于提高三层波纹结构的比吸能。结构优化结果表明:单层结构最优尺寸γ₁为0.8；双层结构最优尺寸为γ₁ = 0.5和γ₂ = 1.2；三层结构最优组合为γ₁ = 0.6，γ₂ = 0.6和γ₃ = 0.9。上述结果可为薄壁夹层结构轻量化设计提供新思路。

Crashworthiness analysis and optimization of bionic corrugated sandwich structures

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 F_p and specific energy absorption E_s 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 F_p 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 E_s, 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 E_s. 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.