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为研究50CrVA高强弹簧钢在变幅荷载作用下的超高周疲劳破坏行为及其裂纹萌生机理,利用超声疲劳试验机对50CrVA弹簧钢进行两级加载实验。得到超高周变幅疲劳性能,并基于Miner法则提出一种适用于超高周疲劳的寿命预测方法。该方法引入应力交互作用影响因子的概念,将预加载对剩余疲劳寿命的影响分为强化和损伤两部分,并分别给出两种影响因素的表达形式以及参数。结果表明,经修正后的Miner法则能对50CrVA的二级加载工况给出较好的寿命预测。
In order to study the ultrahigh-cycle fatigue failure behavior and crack initiation mechanism of 50CrVA high-strength spring steel under luffing load, two-stage loading experiments of 50CrVA spring steel were carried out by ultrasonic fatigue tester. The ultra-high-cycle amplitude fatigue performance was obtained. Based on Miner’s rule, a life prediction method suitable for ultra-high cycle fatigue was proposed. The method introduces the concept of stress interaction factor, and divides the influence of preloading on residual fatigue life into two parts: strengthening and damage, and gives the expression forms and parameters of two influencing factors respectively. The results show that the modified Miner’s rule can give a better life prediction for the second-order 50CrVA loading condition.