Predicting fatigue crack growth rate under block spectrum loading based on temperature evolution using the degradation-entropy generation theorem

Abstract

This study presents the temperature evolution of dual-phase steel in the prediction of the fatigue crack growth rate under block spectrum loading. The degradation coefficient that can be determined from the degradation-entropy generation theorem can be obtained based on the relationship between entropy generation and crack growth. The fatigue crack growth rate under block spectrum loading was then evaluated using the measured surface temperature evolution of the specimen during a fatigue crack growth test. The results of the present model were then compared with experimental fatigue data and the correlation coefficient $$(R^{\mathrm {2}})$$ in all conditions was observed to be more than 0.8. Therefore, the results show that entropy generation of the specimen is a reliable parameter in predicting fatigue crack growth rate under block spectrum loading using the intensity of the degradation coefficient.