基于光纤光栅的悬臂结构疲劳裂纹实验研究

Experimental Study of Fatigue Crack Based on FBG Cantilever Structure

疲劳以及裂纹对机械结构的寿命和生产安全都有着重要的影响。针对叶片等悬臂类结构设计了一种采用光纤光栅进行疲劳测量的方法,通过对比实验证实了裂纹对结构疲劳过程的影响。实验结果表明:完整叶片结构试件的固有频率为124.2Hz,经过5×106次循环后固有频率和光栅波长均无明显变化;而有0.1 mm深度裂纹的固有频率为123.3 Hz,经过5×106次循环后固有频率变为86.68 Hz,证实了裂纹对疲劳寿命的影响。

Fatigue failure and cracks have significant impacts on mechanical structure and working life. In this pa-per,a vane and other cantilever type structures are designed by using fiber grating to measure fatigue,the effects ofcracks on structural fatigue process are proved by contrasting experiments. The experimental results show that：thenatural frequency of the complete structure of sample is 124.2 Hz,after 5×106cycles of trials,the natural frequencyand the center wavelength of sample show no evident change;Meanwhile,the natural frequency of sample with acrack depth of 0.1 mm is 123.3 Hz,after 5×106cycles,the natural frequency becomes 86.68 Hz,this demonstratesthe notable impact of crack on the fatigue life of mechanical structure.