Study On The Fatigue Life And Damage Accumulation Of A Compressor Blade Based On A Modified Nonlinear Damage Model

Comparing with the fatigue test results of Ti-6Al-4V, the widely used Chaboche damage model shows considerable differences in fatigue life prediction under asymmetric load, which is potentially caused by the local plastic deformation. In this paper, a modified nonlinear damage accumulation model is developed to improve the prediction accuracy for asymmetric loading condition. To account for the elastic and plastic strains, an elastoplastic fatigue factor is developed with 2 weighting factors based on the Ramberg-Osgood equation and introduced into the stress term of the damage model. The validation of the proposed damage model is verified against the experimental data of Ti-6Al-4V titanium alloy and 2024-T3 aluminium alloy with various stress ratios. Comparing with the original Chaboche model, the predicted life of the proposed model shows much better agreement with the experimental results. Then, the proposed model is used to estimate the fatigue life of a compressor blade of aero-engine. Considering the variable amplitude loads and the loading sequence, the damage accumulation and the fatigue life of the blade are calculated, and the results indicate a longer fatigue life with slower damage accumulation rate in the early life stage.