基于CAE的模态综合法误差分析

为研究用模态综合法进行发动机舱前端模型NVH分析时的误差,用整体计算法和模态综合法分别进行截止频率为100,200,300,1 000,2 000和3 000 Hz的模态计算,并基于模态计算结果进行原点传递函数计算.结果表明:考虑静态补偿的模态综合法计算误差小于不考虑静态补偿的计算误差;子系统模态计算截止频率大于2倍原点传递函数频率时,模态综合法计算误差小于10%;当传递函数频率是截止频率的1/3时,误差可以降低到5%。

Error analysis on modal synthesis method based on CAE

To study the error of NVH analysis on front-end model of engine cabin using modal synthesis method, the modes under the cutoff frequencies including 100, 200, 300, 1 000, 2 000 and 3 000 Hz are respectively calculated by whole structure calculation and modal synthesis methods. Based on these modal calculation results, the driving point transfer function is calculated. The results show that the calculation error of the modal synthesis method with residual compensation is lower than that without residual compensation; when the modal calculation cut-off frequency of substructures is twice of the frequency of driving point transfer function, the calculation error of modal synthesis method is below 10% ; the error can be even controlled less than 5% if the frequency of transfer function is one-third of cut-off frequency.