锥形变壁厚吸能盒性能研究及关键部位尺寸优化

Energy Absorption Performance and Key Structural Parameter Optimization of a Tapered Crash Box with Variable Wall Thicknesses

摘要

多角度碰撞在车辆事故中较为常见,吸能盒的多角度耐撞性能对于汽车在碰撞过程中的被动安全性和维修经济性有重要影响．引入综合比吸能与初始峰值载荷作为吸能盒在多角度载荷下的综合性能评价指标,以某锥形变壁厚汽车吸能盒为对象,建立了吸能盒准静态压缩过程有限元模型,开展了准静态压缩试验,对比结果显示：仿真与试验的初始峰值载荷相对误差4.6%,比吸能相对误差0.5%．基于最优拉丁超立方设计和有限元模型计算了多种设计变量组合下的综合比吸能和初始峰值载荷,经克里金法拟合吸能盒性能预测代理模型,验证结果显示：二者的拟合优度分别为0.968与0.970．开展了关键尺寸对吸能盒性能影响的灵敏度分析,结果显示：顶部壁厚对综合比吸能影响微弱,对初始峰值载荷影响明显；中段壁厚对综合比吸能与初始峰值载荷都有显著影响；底部壁厚对初始峰值载荷影响微弱,对综合比吸能影响明显,且底部壁厚过小时会导致吸能盒发生整体失稳变形,大幅降低其吸能性能．以综合比吸能最大和初始峰值载荷最小为目标,对吸能盒关键厚度进行多目标优化,结果表明：优化后的吸能盒综合比吸能提高8.37%,初始峰值载荷增加5.73%,在初始峰值载荷增大幅度较小的情况下实现了综合比吸能的较大提升,对变壁厚吸能盒的多角度综合性能优化具有重要指导意义．

Abstract

Multi-angle collisions are relatively prevalent in vehicle accidents. The multi-angle crashworthiness of a crash box plays a critical role in vehicular passive safety and maintenance economy during collisions. In this study, integrated specific energy absorption and initial peak force were established as comprehensive performance evaluation indices for crash boxes under multi-angle loads using a tapered crash box with variable wall thicknesses as the object. Additionally, a finite element model(FEM)of its quasi-static compression process was also established, after which the quasi-static compression experiment was conducted. The comparison results revealed that the relative error of the initial peak force between simulation and experiment was 4.6% and that the relative error of specific energy absorption was 0.5%. Based on the optimal Latin hypercube design and FEM, the integrated specific energy absorption and initial peak force under various design-variable combinations were calculated. The Kriging method was used to fit the surrogate model for predicting the performance of the crash box, and the verification results revealed that their goodness of fit were 0.968 and 0.970, respectively. The sensitivity analysis of the influence of key structural parameters on the performance of the crash box was performed, and the result revealed that the wall thickness at the top exerted weak and strong influences on the integrated specific energy absorption and the initial peak force, respectively. Notably, the wall thickness in the middle section significantly impacted the integrated specific energy absorption and initial peak force, and the wall thickness at the bottom barely impacted the initial peak force and significantly impacted the integrated specific energy absorption. Moreover, when the bottom wall thickness was extremely thin, the crash box succumbed to overall instability deformation, and its energy absorption performance decreased significantly. Employing the maximized integrated specific energy absorption and minimized initial peak force as the optimization objectives, the multi-objective optimization of the thicknesses of its key part was performed. The results indicated that the integrated specific energy absorption and initial peak force of the optimized crash box were enhanced by 8.37% and 5.73%, respectively. A relatively significant improvement in the integrated specific energy absorption was achieved with a relatively slight increase in the initial peak force, representing an important guiding significance for the multi-angle comprehensive performance optimization of the crash box with variable wall thicknesses.

关键词

吸能盒 / 耐撞性 / 轻量化 / 多目标优化

Key words

crash box / crashworthiness / lightweight / multi-objective optimization

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基金资助

国家自然科学基金资助项目(52205166)