新型连续梯度变截面薄壁圆管耐撞性多目标优化设计

Crashworthiness multi-objective optimization design of novel thin-walled circular tube with continuous gradient variable cross-section

提出一种新型连续梯度变截面薄壁圆锥管(FGTT管),其截面直径沿其轴向以一种函数梯度的方式连续非线性变化,较传统等截面薄壁圆管(圆柱管)、连续线性变截面薄壁圆管(圆锥管)具有更好的可设计性及更大的吸能潜力,工程应用价值较大。首先,建立了FGTT管轴向冲击有限元数值模型并进行了精度验证,以此为基础采用有限元数值模拟方法分析比较了FGTT管与传统圆锥管轴向冲击吸能特性,并分析了上下直径差、梯度指数、冲击速度对FGTT管轴向冲击吸能特性影响规律;在此基础上,以FGTT管壁厚、上端半径和梯度指数作为设计变量,以其轴向冲击比吸能和初始峰值力为优化目标,结合拉丁超立方试验设计、响应面近似模型及NSGA-Ⅱ多目标优化算法对其进行了耐撞性多目标优化设计。优化结果表明:优化后的FGTT结构与初始常规圆锥形结构相比,初始峰值力得到了很大程度的改善,下降了45.4%;比吸能较原结构提高了13.5%;与原结构相比,该FGTT结构的质量减少51.031%,取得了良好的优化设计效果。

This paper proposes a novel continuous gradient variable cross-section thin-walled circular tube(FGTT),whose cross-sectional diameter changes continuously and non-linearly in a functional gradient along its axial direction.Compared with the traditional uniform cross-section thin-walled circular tube(cylindrical tube)and continuous linear variable cross-section thin-walled circular tube(conical tube),it has better designability and greater energy absorption potential,and has greater engineering application value.First,the FGTT tube axial impact numerical simulation model was established and the accuracy was verified.Based on this,the numerical method was used to analyze and compare the axial impact energy absorption characteristics of the FGTT tubes and the traditional conical tubes.Then,the influence of the upper and lower diameter difference,gradient index,and impact velocity on the axial impact energy absorption characteristics of FGTT tubes is analyzed;on this basis,the wall thickness,upper end radius and gradient index of the FGTT tube are used as design variables,and take the axial impact specific energy absorption and initial peak force as the optimization goal,combined with Latin hypercube test design,response surface approximation model and NSGA-II multi-objective optimization algorithm to carry out multi-objective optimization design for crashworthiness.The optimization results show that compared with the original conventional conical structure,the optimized FGTT structure has a greatly improved initial peak force,which is reduced by 45.4%;the specific energy absorption is also increased by 13.5%compared with the original structure.At the same time,the mass of the FGTT structure is also reduced by 51.031%,achieving a good optimization design effect.