基于轻量化及刚度的铝合金车体承载结构参数选择研究

摘要

将铝合金车体型材分为6个区域，以每个区域型材厚度变化百分比为变量，用 Box-behnken试验设计法确定样本空间，通过确立的样本空间确定车体垂向弯曲频率、扭转频率、抗弯刚度、抗扭刚度与型材厚度变量的关系式。把N 维空间关系式映射到二维和三维空间，分析车体固有频率和刚度随不同区域型材厚度变化关系，确定厚度对频率和刚度敏感区域。用多目标函数优化方法对车体参数进行优化，选取合适的型材参数使车体满足频率和刚度的要求，并实现车体设计轻量化。优化结果和有限元验证结果表明：根据样本空间确立的关系式优化结果和有限元计算结果能较好吻合，优化后车体强度满足要求，Box-behnken试验设计方法应用在车体参数优化和样本空间的建立上具有可行性。本文可为车体轻量化设计提供一种新的方法。%The aluminum alloy car body profile was divided into six areas,with the thickness variation percent-age of the profile of each area being selected as variables.The Box-behnken method was used to determine the sample space,through which,the quadratic polynomial was established to determine the relationship between the vertical bending frequency,torsional frequency,bending stiffness and torsional stiffness with the profile thickness variables.The N-dimensional space was mapped to 2D space and 3D space to analyze the relations be-tween the natural frequency and stiffness of the car body with the variation of the thickness of the profile in dif-ferent regions,and to determine the sensitive areas of thickness to frequency and stiffness.In the end,the vehi-cle body parameters were optimized based on multi-obj ective optimization method to select the appropriate pro-file parameters to satisfy the requirements of frequency and stiffness of the car body and to realize the light weight design.The optimization results and the finite element validation results showed that the results of the optimized relationship based on sample space coincided with the finite element calculation results.The strength of the optimized car body met the requirements.The Box-behnken experimental design method is applicable to the optimization of car body parameters and the establishment of the sample space.Thus,it provides an ideal way for vehicle lightweight design.