PROBABILISTIC APPROACH TO THE SHORT AND LONG FATIGUE CRACK GROWTH DESCRIPTION IN A NOTCHED MEMBER

摘要

The paper presents probabilistic approach to prediction the short and long fatigue crack growth in the notched members. A finite differences equation which models the dynamics of the changes caused by fatigue and the Paris formula are the core of the concept. An appropriate transformation applied to the difference equation has resulted in the Fokker-Planck partial differential equation which is the source of a probability density function of a Gaussian shape. The resolved function allows one to calculate the average crack length and standard deviation of crack length. In order to calculate these values the central moments method was applied. The capability of the probabilistic approach has been verified using experimental data gained for a medium carbon steel and a titanium alloy fatigued under reversed bending.