循环系数修正的膜片弹簧疲劳寿命分析

摘要

基于有限元精确应力结果运用循环系数修正的疲劳积累理论对膜片弹簧寿命分析,并讨论工作位置对寿命影响.对膜片弹簧大端加载有限元分析,验证有限元算法精确性;对膜片弹簧疲劳测试工况应力分析,剔除预紧与松紧过程应力,运用基于应力控制的疲劳损伤理论,并用循环系数修法正对其修,对膜片弹簧疲劳寿命分析.借助Ncode Designlife平台Time Step模块,通过计算方法获得零件疲劳危险点位置,与以往实验一致,且与疲劳测试相符.精度较以往计算有较大提高,且该方法可用于所有周期性工作零件疲劳寿命预测.讨论了工作位置对膜片弹簧影响,当工作位置位于极大值点与拐点之间并尽量远离拐点时,膜片弹簧既能发挥其非线性弹性特性,又能保持较高的疲劳寿命.%To offer the fundamental of fatigue design of diaphragm spring,the cumulative fatigue damage theory has been used to calculate the fatigue life of diaphragm spring based on the current stress history data,and the impact of working position had been discussed.Loading on large side had been analyzed by using FEM firstly,after that the experimental results have been obtained to verify the FEM calculated results.Secondly the stress data in fatigue test condition had been calculated by using FEM,and the stress data of preloading and unpreloading were removed.With the remaining stress history data,the stress controlled fatigue damage method had been used considering the cycle ratio modification to analyze the fatigue life.To make the process easier Time Step module in Ncode Designlife had been used,the calculated result indicated that the danger point position is same as the previous literature and match with the fatigue test.The calculated accuracy of fatigue damage had been greatly improved,and the danger point position of fatigue damage can be directly calculated,besides,it can not only be used for a diaphragm spring but also for other cyclical working component.At last,the impact of working position had been discussed,which identify that when the working position is between the local maximum value point and the inflection point,and keep a distance to inflection point then a diaphragm spring can behave nonlinear as well as a longer life.