An improved strength degradation model for fatigue life prediction considering material characteristics

Abstract

Experimental results show that when the loading sequence of fatigue loads changes, the fatigue cumulative damage prediction based on Miner's rule will have a large error, even as high as 252.83%. In an effort to improve the fatigue life predictions, based on the residual strength degradation rule, a power exponential fatigue equivalent damage model is presented in this paper, which contains two material parameters. Experimental data were cited to verify the residual strength model, and the statistical results showed that this model is capable of describing the residual strength degradation of materials. Furthermore, a fatigue cumulative damage model based on residual strength is established to predict the fatigue life. The Miner's rule and other models were compared to validate the model by referring to the test data of different materials under different loading stress levels. And the accuracy of the fatigue life predicted by this model is twice as good as that predicted by others models.