Detection Method of Acceleration of Fatigue Crack Growth after Overloading or Underloading

Abstract

When an unexpected overload or underload was applied a cracked material during usual operation under constant stress amplitude, an acceleration or deceleration of the crack growth was observed depending on the experimental conditions. In the present study, a method of detecting the application of an unexpected dangerous load was investigated. 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 daily inspection. In the present study by using center-crack specimen, a simple method of detecting application of overload or underload was investigated.