The Effect of Overload Variation on the Fatigue Crack Behavior at the Axial Direction Hole Defects

과대하중변화가 축방향 원공결함의 피로균형거동에 미치는 영향

It is difficult to explain the effects of complex variable loading experienced by the machine and the structure only with the studies of the single-overload itself. Hence, it is thought that the variation of overload-holding time are required to explain the effects more clearly. The effects of the overload were analyzed by means of the crack retardation, and the fractography on retardation zone. A characteristic of the fractography on retardation zone was that striation distribution did not appear due to decreased crack driving force. Rotary bending fatigue tests were performed with the circular shaft which has two hole defects.