中文摘要：

本文中综合考虑汽车低速碰撞中的角度和对中两种碰撞工况,结合碳纤维/环氧树脂材料的特点,提出了一种变截面复合材料前防撞梁设计方法。首先,通过低速碰撞两种工况中前防撞梁的仿真计算发现,在等厚度的情况下,为满足侵入量的条件,对中碰撞时所要求的厚度远远大于角度碰撞时的要求,因此,根据对中碰撞时前防撞梁的受力和约束条件,为其提出了中间厚两端薄,即变截面的设计方案。然后,以最小化吸能盒截面力和前防撞梁质量为目标,许用侵入量为约束,两种截面厚度和加厚区域长度为设计变量,基于采集的试验点构建吸能盒截面力和前防撞梁质量的Kriging代理模型,利用NSGA-Ⅱ算法对其进行多目标优化。最终的结果表明,在满足性能要求的基础上变截面设计使复合材料前防撞梁的质量分布更为合理,在不增加质量的条件下,角度和对中两种低速碰撞工况中耐撞性能都得到提高。

英文摘要：

With concurrent considerations of both angular and centered impact conditions in vehicle lowspeed crash,combined with the features of carbon fiber/epoxy material,a design scheme of composite front bumper with variable cross section is proposed in this paper.Firstly a simulation on front bumper in both angular and centered low-speed impacts show that for meeting the intrusion conditions of front bumper with uniform thickness,the required thickness for centered impact is far larger than that for angular impact.Based on this,according to the force bearing and constraint conditions of front bumper in centered impact,a design scheme of variable cross section（thicker in center part and thinner in both ends）is proposed.Then with minimizing the section force of energy absorbing box and the mass of front bumper as objectives,the allowable intrusion as constraint,and the two section thicknesses for center part and both ends respectively and the length of the thicker center part as design variables,a multi-objective optimization is conducted by using NSGA-Ⅱ algorithm and Kriging surrogate model for the section force of energy absorbing box and the mass of front bumper constructed based on the test data collected.Finally the results indicate that the variable section design scheme proposed leads to more reasonable distribution of the mass of front bumper and its crashworthiness in both angular and centered impacts are enhanced without the increase of its mass.