副车架系统边界约束对计算模态分析精度的影响研究

The Effect of Subframe System Boundary Constraints on the Accuracy of Computational Modal Analysis

针对某车型＂刚性＂副车架系统建立有限元模型,以约束处理方式为设计变量,以0－200Hz范围内的约束模态频率计算值与试验值的误差作为评价指标进行正交试验设计,分析得到不同约束处理方式对副车架约束模态分析精度的影响规律。结果表明：副车架与车身连接点处车身局部刚度对模态分布的影响较大,悬架摆臂次之,衬套动刚度对模态分布的影响相对较弱;基于正交试验遴选出的最佳边界约束处理方式,可得约束模态频率计算值与试验结果的相对误差为0.45%,达到了理想精度。

FE model of a vehicle ＂rigid＂ subframe system is established, the influence law of different constraint processing modes on the accuracy of subframe constraint modal analysis is obtained through analysis with the constraint processing mode as design variable, and the error between constraint computational modal frequency and experimental value in the range of 0~200 Hz as evaluation criteria for the orthogonal experimental design. The results show that the local stiffness of the joining part between subframe and body is the most important factor to affect modal distribution, followed by the suspension swing arm, whereas the sleeve dynamic stiffness affects modal distribution slightly; the optimal boundary constraint processing mode is selected based on orthogonal experiment, and it is concluded that the relative error of the computational modal frequency compared with the experimental one is 0.45 %, thus a relative ideal accuracy is obtained.