估算变幅疲劳寿命的等效折算法

介绍了估算变幅疲劳寿命的等效折算法。该法的主要思想是通过特定的等效寿命函数,依次将变幅疲劳中的各级循环次数均等效折算为某一循环下的已耗寿命,即将变幅疲劳转化为等幅疲劳,来估算其寿命。给出了两种形式的等效寿命函数,一种考虑了变幅疲劳的加载次序效应,另一种则适用于加载次序效应不强的随机性谱载。四种材料的实际评估结果显示,无论对于分级加载还是随机性谱载,该法的寿命预测精度均明显高于同类型的其它五种方法。该法仅依赖于等幅试验数据,不含任何待定参数,计算简单,适合于工程运用。

Equivalent-Conversion Method for Estimation of Various Amplitude Fatigue Life

An equivalent conversion method for estimation of various amplitude fatigue life is introduced, where the cycles under different loading levels of various amplitude fatigue are equivalently converted to the expended life under one loading level, i.e., the life of various amplitude fatigue is estimated by transforming it into constant amplitude fatigue. Two types of the equivalent life function are presented, one takes loading sequence effect of various amplitude fatigue into account, and another fits random spectrum loading without loading sequence effect. The evaluation results of four materials show that the life prediction accuracy is much higher than one of competing methods, five, ie., Miner Law, Modified Miner Law, Manson Double Line Rule, Root Mean Square Method and Modified Root Mean Square Method. The method conveniently to apply to engineering as it only depends on the constant amplitude fatigue test data, doesn't contain any parameter to be determined.