Random outcome and stochastic analysis of some fatigue crack growth data

Fatigue crack propagation data of a batch of AISI 4340 steel specimens are released in the present paper. The statistical nature of the data is specia lly emphasized, and a probabilistic fracture mechanics model is introduced to analyze the data. The stochastic differential equation associated with t he model is then solved. The solution gives us the crack exceedance probabi lity as well as the probability distribution of the random time to reach a specified crack size. These quantities are useful in the reliability assess ment of structures made of the tested material. Comparing the analytical re sult with the experimental result, it is found that the proposed probabilis tic fracture mechanics model can reasonably explain the experimental data. For those data that cannot be fitted well by the proposed model, methods of improvement are proposed in the present paper as well.