动力总成悬置系统固有频率和解耦率的区间分析方法

摘要

在动力总成悬置的制造、安装和汽车的使用过程中,悬置的刚度存在一定程度的不确定性.因此,悬置系统的频率和解耦率必然不是确定值.为研究悬置系统频率和解耦率的变化特征,进而解其性能的稳健性,文中给出一种区间分析方法.在已知悬置刚度的变化范围而不需解其统计特性的情况下,用区间数学中的区间数描述其变化的不确定性,基于组合方法计算悬置系统固有频率和解耦率的精确变化范围.给出区间可靠度的计算公式,用于表征悬置系统频率和解耦率的设计稳健性.计算某轿车悬置系统的频率以及沿垂直方向和绕发动机曲轴扭转方向解耦率的区间可靠度.计算结果表明,当悬置刚度在其设计名义值附近波动时,动力总成悬置系统的悬置刚度需要进行优化,以提高固有频率及垂直方向和绕发动机曲轴扭转方向解耦率的设计稳健性.%The mounting stiffness of powertrain mounting system (PMS) of vehicles has some uncertainty in the process of manufacturing, installation and vehicle operation, therefore the PMS frequency and decoupling ratio are also uncertain. To investigate the variation characteristics of the frequencies and decoupling ratios, an interval analysis method was proposed. In the case that the range of the mounting stiffness variation is known while its stochastic characteristics are unknown, the interval number in interval mathematics can be employed to describe the uncertainty of the mount stiffness variation. The variation range of the intrinsic frequencies and the decoupling ratios of the PMS were calculated accurately with the application of the combination method. The interval reliability formula was given to describe the robustness of the frequencies and decoupling ratios. The interval reliabilities of frequencies and decoupling ratios in the vertical and pitch directions were calculated. Computational results show that the mount stiffness parameters need to be optimized in order to increase the interval reliabilities of the frequencies and the decoupling ratios in vertical and pitch directions.