考虑碰撞安全性的电动客车车身截面尺寸优化

Optimization of Sectional Size of Electric Bus Body Considering Crashworthiness

针对承载式车身结构的电动客车在正面碰撞中安全性较差的问题,结合有限元网格变形技术对客车前端管梁结构进行碰撞安全性和轻量化多目标优化设计。建立了客车碰撞分析有限元模型并对碰撞后的评价指标进行了分析,选取了在正面碰撞中吸能量占比较大的管梁结构作为优化区域,以选取出的管梁截面的长度、宽度和厚度作为设计变量,引入驾驶舱4个关键位置的侵入量、前端结构的吸能量、峰值侵入速度和设计区域总质量作为优化响应,通过灵敏度分析得到各设计变量对优化响应的贡献度值,基于熵权法和优劣解距离法(technique for order preference by similarity to an ideal solution,TOPSIS)综合权重方法,筛选出对优化响应综合贡献度较高的设计变量,最后结合拉丁超立方实验设计、响应面法(response surface method,RSM)和NSGA-Ⅱ算法对客车前部区域结构进行了多目标优化。研究结果表明:多目标优化后,驾驶员胸部生存空间提升6.28%,腿部生存空间提升9.7%,选取点峰值侵入速度降低6.1%,客车前端吸能结构吸能量提升8.3%,同时实现客车前端结构质量减轻15.187 kg,减重率为6.58%。

Aiming at the problem of poor safety of electric bus with load-bearing body structure in frontal collisions,the optimizing design of the front structure of an electric bus was conducted orienting the performance of lightweight and crashworthiness.The optimization was performed by optimizing the cross section of the steel beam of the body frame by the mesh morphing technology.A finite element model for electric bus was established and the evaluation indicators after the crash were analyzed.The steel beam with a large energy absorption in the frontal collision was selected as the optimization area,and the length,width,and thickness of the selected steel beam were selected as the design variable.Taking the intrusion at 4 key positions of the cockpit,the energy absorption of the front structure,the peak intrusion velocity and the total mass of the design area as optimization responses.Through sensitivity analysis,the contribution of each design variable versus the optimization response was obtained.Based on the entropy weight method and the technique for order preference by similarity to an ideal solution(TOPSIS)comprehensive weight method,the design variable with a higher comprehensive contribution to the optimized response was obtained.Finally,the multi-objective optimization of the front structure of the electric bus was carried out by combining the Latin hypercube experimental design,response surface method(RSM)and NSGA-Ⅱalgorithm.The research results show that after multi-objective optimization,the driver's chest living space is increased by 6.28%,the leg living space is increased by 9.7%,the peak intrusion velocity of the selected point is reduced by 4.97%,and the energy absorption of the front end of the bus is increased by 8.3%,and the weight of the structure the front end of the bus is reduced by 15.187 kg,the weight reduction rate is 6.59%.