A Method for Detecting an Unexpected Application of a Hazardous Load During Operation

A method for detecting the application of an unexpected dangerous load was investigated. An acceleration behavior of crack growth due to the application of overload and or underload during fatigue crack growth test with constant stress amplitude was observed. In some cases, the acceleration of crack growth brings catastrophic failure in machine structure. Therefore, it is useful for machine maintenance to know whether an unexpected load was applied or not by doing a daily inspection. In the present study by using center-crack specimen, a simple method of detecting the application of overload or underload was investigated. Such an unexpected load can be detected by the waveform of the function of stress and strain in the vicinity of the crack.