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判断汽车零部件实际使用寿命的方法有应用累积疲劳损伤定律进行计算的方法及进行程序疲劳试验的方法等等。但是,在这些方法中,还存在着加载的顺序,微小应力的处理及频次计数方法的选择等问题。作为解决这些问题的手段,考虑了利用从实际的随机波中除去对疲劳寿命没有影响的小振幅,将此程序随机波进行疲劳试验的方法。在这种方法中,最重要的一点是如何确定所除去的小振幅的上限。为此,采用四种带缺口的试验片,用实际的随机波及与此相对应的程序随机波进行疲劳试验。结果,搞清楚了对应于裂纹发生寿命的无效振幅取决于疲劳极限,对应于裂纹传播寿命的无效振幅取决于n/N的分布。根据试验结果定量地确定了无效振幅的除去基准;另外,也证实了可以大大缩短疲劳试验的时间。
The method of judging the actual service life of auto parts includes the method of applying cumulative fatigue damage law and the method of fatigue test. However, among these methods, there are still some problems such as the order of loading, the treatment of tiny stress and the selection of the frequency counting method. As a solution to these problems, a method of performing fatigue tests using random waves of this program by using a small amplitude that has no effect on the fatigue life from the actual random waves has been considered. In this method, the most important point is how to determine the upper limit of the small amplitude removed. To this end, the use of four notched test pieces, with the actual random wave and the corresponding program random wave fatigue test. As a result, it is clear that the null amplitude corresponding to the lifetime of the crack depends on the fatigue limit, and the null amplitude corresponding to the crack propagation life depends on the n / N distribution. Based on the results of the experiment, the criterion of removal of the ineffective amplitude was quantitatively determined. In addition, it was confirmed that the fatigue test can be greatly shortened.