变幅载荷下孔挤压件疲劳裂纹起始寿命的估算方法

METHOD FOR PREDICTING FATIGUE CRACKINITIATION LIFE OF ELEMENTS SUBJECTED TOCEH UNDER VARIABLE-AMPLITUDE LOADING

本文研究了孔挤压与超载复合强化对LY12CZ铝合金疲劳裂纹起始寿命的影响。实验结果表明,复合强化对该合金的疲劳裂纹起始寿命及裂纹萌生、扩展特性的影响与孔挤压强化的效果相同,得出了复合强化后疲劳裂纹起始寿命的定量表达式。据此,提出了变幅载荷下孔挤压件疲劳裂纹起始寿命的估算方法,实验证明该方法是可行的。

Experimental study has been carried out on the effects of the com- plex strengthening of the cold expansion of hole (CEH) and overloading on the fa- tigue crack initiation life (FCIL) of LY12CZ alloy The overloading has no appreciable effect on FCIL of LY12CZ alloy after CEH. Moreover, an expression for FCIL of LY12CZ alloy subjected to the complex strengthening is given. Based on the above-mentioned results, a new method is put forward to predict the FCIL of LY12CZ alloy after CEH under variable amplitude loading and has been substantiated by the fatigue tests under a flight-to-flight spectrum.