Fatigue reliability analysis of crack growth life using maximum entropy method

摘要

In this article, a new method for fatigue reliability analysis of crack growth life based on the maximum entropy theoryand a long crack propagation model is proposed. A modified generalized passivation-lancet model for long fatigue crackpropagation rate is presented with explicit physical meaning. Experimental results for turbine disk alloy ZSGH4169under different strain ratios and temperatures (at 650 C and room temperature) are used to verify the applicability ofthe new model. Results show that predictions by the proposed model are almost identical to the experimental data. Thepresented model is better than the other three models to reflect the rapid propagation characteristics of the crack. Inorder to perform fatigue reliability estimation, the probabilities of failure are calculated using the maximum entropy theory based on the fatigue crack growth life that derived from the proposed modified crack propagation model and theabove existing three models. Results have shown that maximum entropy theory is very apt for fatigue reliability analysisof turbine disk under different loading conditions with a limited number of samples because it does not need any distribution assumptions for random variables. The effectiveness and accuracy of the combination of fatigue crack propagationmodels and maximum entropy method for fatigue reliability analysis are demonstrated with examples.