Randomization analysis of the thermal-mechanical crack growth

In order to describe the crack growth law under thermal-mechanical loading, the linear superposition model of fatigue and creep crack growth was amended based on the experimental results. New material parameters in the model were determined, as the original ones may not be independent of the stress ratio, temperature and dwell time due to the influence of alternating load to the creep crack propagation. Then, a random crack growth model was obtained by introducing lognormal random process to the amended model. With the Taylor series expansion, the distribution of the crack size at any service time and the distribution of the service time to reach any crack size were attained. An example was given to validate the reliability of the proposed randomization method by comparing the life distribution obtained from the model with the experiment.