废劳裂纹扩张速率da/dN是断裂力学中的重要参数之一,它对于估算构件的寿命有重要的意义。只要记录一定循环次数下的裂纹长度,就可以计算出裂纹扩张速率来。目前经常采用的测定裂纹长度的方法当中,各有一定的缺点:显微镜法不能连续自动地记录,常需中断试验来进行测量;电阻法(或电位法)不能直接测量裂纹长度,需经复杂 The fatigue crack growth rate, da / dN, is one of the important parameters in fracture mechanics. It is of great significance for estimating the life of the component. Just record the number of cracks in a certain number of cycles, you can calculate the rate of crack growth. At present, there are some shortcomings in the methods of measuring crack length, which are often used at present: the microscope method can not continuously and automatically record and often need to interrupt the test to carry out the measurement; the resistance method (or potential method) can not directly measure the crack length,