综合考虑疲劳强度影响因素的寿命预测方法

目的提出一种综合考虑疲劳强度影响因素的寿命预测方法。方法利用提出的综合疲劳强度因子Kz考虑应力集中、尺寸和表面状态等因素对疲劳强度的影响,结合S-N曲线方法,采用Goodman方程进行平均应力修正,采用Miner定理进行疲劳损伤累积,提出一种适用于机械结构的疲劳寿命预测方法。结果对一种复杂结构螺旋弹簧进行了位移控制的恒幅和变幅台架试验,并利用弹塑性有限元分析获得了关键危险点位置的应力响应历程。利用台架试验的寿命结果对提出的方法进行了验证,预测误差在2倍因子以内。结论提出的方法可以较好地预测机械结构的疲劳寿命。

Life Prediction Method Synthetically Considering the Influence Factors of Fatigue Strength

The paper aims to propose a life prediction method synthetically considering the influence factors of fatigue strength. The proposed comprehensive fatigue strength factor Kz was adopted to consider the effects of stress concentration, size and surface state on fatigue strength. Based on S-N curve method, Goodman equation was used to modify the average stress. Miner theorem was used to accumulate the fatigue damage. And a fatigue life prediction method suitable for mechanical structures was proposed. The constant amplitude and variable amplitude displacement controlled bench tests for a complex structural helical spring were carried out. The stress response history of the key dangerous point was obtained by elastoplastic finite element analysis. The proposed method was validated by the results of bench test, and the prediction errors were within a factor of 2. The proposed method can predict the fatigue life of mechanical structures well.