一种较简单的低循环疲劳寿命预测法

A SIMPLE PREDICTION METHOD FOR LOW-CYCLE FATIGUE LIFE OF STRUCTURES

1。引言 局部应力应变法是目前预测结构裂纹起始寿命的一种行之有效的方法。根据局部应力应变法的原理,可以用计算的方法来预测构件裂纹起始寿命。在计算中,从载荷谱得到局部应变谱,可利用有限元法分析结构的局部应力应变响应。当然还可利用半经验公式(如Neuber法等)。在计算中若考虑材料的记忆特性和循环σ-ε曲线,这无疑对真实地反映受载构件的局部应力应变响应是有利的。但要做到这一点,用有限元分析所需的机时相当可观,因为它要对整个寿命期间的载荷历程进行分析计算,至少也要针对一个典型谱分析计算。

A simple prediction method for low-cycle fatigue life of structure under field load is described. Under rotating speed spectrum, the prediction for fatigue life of jet engine compressor disk is given. The predicting results are compared favorably with actual test results for the same material and under the same rotating speed spectrum. The key in this prediction is to obtain typical load(P) versus local damage(D) curve(P-D)at the critical load, existing material propertices and plasticelastic F.E.M. The fatigue life of structures can be determined with the P-d curve and field specturum by computer program. Therefore, the prediction can save time and money, and the results are satisfactory.