An improved manson-halford model for multi-level nonlinear fatigue life prediction

The Manson-Halford (M-H) nonlinear fatigue damage model is widely used for fatigue damage analysis. It, however, does not consider the load interaction effect. This paper presents an improved M-H model with a load interaction factor defined as the ratio of the first and second stress levels. The characteristic exponent of the M-H model is modified by multiplying the load interaction factor and fatigue life ratio. The characteristic exponent can consider the load interaction effect and the load sequence effect under multi-level loading. Experimental data from five materials under two-level and multi-level stress loadings verify the accuracy of the proposed model.