Metallic/non-metallic fatigue life prediction model considering load interactions under variable load conditions

Abstract

Under variable amplitude loading, the fatigue damage accumulation in metallic and non-metallic materials is significantly influenced by load interaction effects, which are challenging to predict accurately using traditional linear damage theory. Building upon this, this study integrates the fatigue crack propagation mechanism with nonlinear damage evolution theory and introduces a load interaction factor after thoroughly analyzing the influence of load sequence effects on the fatigue life of metallic and non-metallic materials. A fatigue life prediction model is then proposed under an adjustable stress ratio condition. By comparing the proposed model with Miner’s model, Aeran’s model and its modified version, as well as Aodi Yu’s model, and validating it against experimental data from typical metallic and non-metallic materials, the results demonstrate that the proposed model significantly enhances the accuracy of fatigue life prediction and outperforms traditional linear theories in capturing load interaction effects.