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基于方管理想化折叠单元模型、塑性挤压过程能量耗散分解法与棱边强化薄壁方管在轴向静态压溃作用下的能量平衡修正方程,分别导出了棱边强化薄壁方管的平均压溃力、吸能预测与棱边强化效果的理论表达式。建立了系列棱边强化薄壁方管准静态轴向压溃有限元模型,导入LS-DYNA程序进行弹塑性动力学仿真,获得了平均压溃力,分析了棱边应力强化的敏感性。将棱边强化技术应用于某车前保横梁和吸能盒相应棱边强度设计中,采用超高应力强化棱边和普通延性钢板组合去置换较高强度钢薄壁结构,在冲击试验验证过的有限元模型基础上,建立了棱边强化前保险杠子结构独立评价有限元模型,分别进行了棱边强化模型和原始模型的50km·h~(-1)正碰仿真试验。仿真结果表明:导出的平均压溃力公式可以预测棱边与平板屈服强度比为1~4的棱边强化薄壁方管轴向压溃力学特性,仿真结果与理论结果的最大偏差不超过5.66%;由前保险杠子结构正碰仿真结果得到了棱边强化前后近似的塑性变形模式与传力路径,能量吸收差值不超过0.3kJ。可见,选择性棱边应力强化后的普通延性钢前保险杠子结构有望实现等效置换较高强度钢前保险杠子结构。
Based on the equations of energy conservation of the square-tube-like idealized folded cell model, the energy dissipative decomposition of plastic extrusion process and the energy balance correction equation under axial static crushing of the square-walled reinforced thin-walled square tube, the average crush Force, energy absorption prediction and edge enhancement effect of the theoretical expression. A series of finite element models of quasi-static axial crushing of square-walled reinforced thin-walled square tubes were established. The LS-DYNA program was used to simulate the elasto-plastic dynamics and get the average crushing force. The sensitivity of the edge stress intensification was analyzed. The edge reinforcement technology is applied to the design of the corresponding edge strength of a car front beam and energy absorbing box. The combination of ultra-high stress-strengthened edge and common ductile steel plate is used to replace the high-strength steel thin-wall structure. After impact test, Based on the finite element model, an independent evaluation finite element model of the front bumper reinforcement structure with edge reinforcement was established. The 50km · h -1 frontal impact simulation of the edge reinforcement model and the original model was carried out respectively. The simulation results show that the derived average crushing force formula can predict the axial crushing mechanical properties of the edge strengthened thin - walled square tube with edge - plate yield strength ratios of 1 ~ 4. The maximum deviation from simulation results does not exceed 5.66%. The approximate plastic deformation mode and force transmission path before and after the edge reinforcement are obtained from the frontal impact simulation results of the front bumper structure. The energy absorption difference does not exceed 0.3kJ. It can be seen that the normal front bumper sub-structure of ductile steel after selective edge stress strengthening is expected to achieve the equivalent replacement of the higher-strength steel front bumper sub-structure.