碳纤维复合材料防撞梁与铝合金吸能盒低速碰撞轻量化设计优化

Lightweight Design and Optimization of Carbon Fiber Composite Bumper Beam and Aluminum Alloy Crash Box for Low Speed Impact

为了提升车身前端轻量化性能,本文设计与优化了一种新型结构的碳纤维复合材料防撞梁与铝合金吸能盒。首先,建立了某乘用车钢制车身前端的有限元模型,并验证了模型的准确性。然后,运用拓扑优化技术对防撞梁及吸能盒进行拓扑设计,优化出其最优形状,确定新型防撞梁及吸能盒的三维模型。结合新型防撞梁及吸能盒模型,通过自由尺寸优化、尺寸优化和铺层顺序优化,对碳纤维复合材料防撞梁铺层进行优化,确定其最佳铺层块、铺层角度及铺层顺序。最后,基于碳纤维复合材料防撞梁及铝合金吸能盒低速正面碰撞有限元模型,设置6个设计变量和5个响应,采用最优拉丁超立方法对各设计变量随机取样,以构建各响应值的Kriging近似模型,运用NSGA-Ⅱ算法对防撞梁及吸能盒进行多目标优化,确定其最佳厚度。优化结果表明:与优化前相比,优化后吸能量为787.993 J,下降0.25%;吸能盒截面碰撞力峰值为20.2085 kN,下降了58.67%;最大侵入量为-64.2847 mm,增加了118.69%;防撞梁及吸能盒总质量为0.9537 kg,降低了45.34%。优化后碳纤维复合材料防撞梁及铝合金吸能盒在满足碰撞性能要求的条件下,比原钢制材料结构质量减少了67.2%,轻量化效果显著。

To improve the lightweight performance of frontend structure,a new type of carbon fiber composite bumper beam and crash box was designed and optimized in this paper.First,the finite element model of the steel vehicle body front structure was established and its accuracy was verified.Second,topology optimization technique was applied to design the bumper beam and crash box.The cross-section shape was optimized and the three-dimensional model of the new bumper beam and crash box was determined.According to the model of new bumper beam and crash box,the layup of carbon fiber composite anti-collision beams was optimized through free size optimization,size optimization and layup sequence optimization,to determine the best layup block,layup angle and layup sequence.At last,6 design variables and the 5 responses were collected by the finite element model of the carbon fiber bumper beam and aluminum alloy crash box for low-velocity impact.With OptLHD method,the Kriging surrogate model was fitted based on the simple points,which was used for multi-objective optimization conducted by using NSGA-Ⅱalgorithm.Compared with the preoptimization structure,the optimization results show that the energy absorption of the optimized structure reaches to 787.993 J,which is decreased by 0.25%.The collision force reaches to 20.2805 kN,which is reduced by 58.67%.The collision of bumper beam reaches to 64.2847 mm,which is increased by 118.6%.The total weight of bumper beam and crash boxes reaches to 0.9537 kg,which is decreased by 45.34%.Compared with the original steel structure,the weight of the carbon fiber composite bumper beam and aluminum alloy crash box is reduced by 67.2% and its lightweight effect is remarkable.