A STATISTICAL ANALYSIS OF SHORT FATIGUE CRACK GROWTH

Abstract This paper explores short fatigue crack growth behaviour in torsion and tension at the same equivalent stress level of 880 MPa. Quantum steps (i.e. crack growth following crack arrests at grain boundaries) occurred randomly along the curve of crack length vs number of cycles applied. A statistical model for the short crack growth process is presented in the form of a non‐stationary Markov chain which can be described with a probabilistic transformation matrix. The endurance mean value is described with a prescribed confidence level. Fatigue life, with a high degree of survivability, is determined with respect to a specified crack length. This should assist engineers concerned with the damage‐tolerant design of critical components.