随机载荷下焊接结构疲劳寿命的一种有效计算方法

随机载荷下的疲劳寿命估算方法通常涉及两个方面，循环计数和损伤累积。本文研究了一种用于随机载荷下焊接构件疲劳寿命预测的有效计算方法。按照这种方法，只要求已知应力历程的功率谱密度和常规疲劳试验数据，就可以对承受随机载荷的焊接构件作出疲劳寿命计算。利用结构系统的复频响应函数，可以由已知的输入功率谱求出结构响应的谱密度。这就使得结构设计者即使在设计阶段不知道结构承受的应力历程，而只知道结构系统的输入，也同样可以对所设计的结构作出疲劳寿命预测。本文所述方法被用于某超重型矿用汽车车架的疲劳寿命计算，计算结果与实际情况基本吻合。

EFFECTIVE FATIGUE LIFE PREDICTION METHOD FOR THE WELDED STRUCTURES UNDER RANDOM LOADING

The conventional method of fatigue prediction under random loading traditionsily involves two data processes of cycle counting and damage summation. This paper introduces an effective fatigue life prediction method for the welded structures under random loading. According to the method, the fatigue fife prediction for welded structures under random loading can be made directly only from a knowledge of the Power Spectral Density (PSD) of the stress history and conventional fatigue data. Even though the designer of structures does not know the stress-time history at the design stage, but with the exact inputs of the structures, the fatigue life prediction for the designed structures can still be made since the PSD of structures response function of the structural system. The method described in the paper is applied to an extraheavy mining truck frame. The enlaslated fatigue life is basically the same as that with the practice.