A Statistical Study on Fatigue Life Distribution Based on the Coalescence of Cracks from Surface Defects

Abstract

Rotating bending fatigue tests were carried out on SUS304 stainless steel specimens having three drilled holes with equal distance at the critical section to investigate statistically the propagation behavior of surface cracks and their coalescence leading to a failure of the specimen. Based on the distribution characteristics of crack length at an arbitrary number of cycles, a statistical evaluation was made on the coalescence of cracks as a function of the number of cycles, and the fatigue life distribution was theoretically derived from the above evaluation assuming that the failure occurs immediately after the coalescence of cracks. The analytical results obtained are in good agreement with the experimental results of fatigue life distribution.