A non-linear model for predicting fatigue damage accumulation in composite materials: Application of Weibull statistics and reliability analysis

Abstract

This study investigates the interlaminar shear fatigue behavior and fatigue life prediction of a high-performance laminated composite material under constant amplitude cyclic loading at various stress levels and load ratios ( R τ = 0.1 and −1). Fatigue tests were conducted on 32 specimens at five normalized shear stress levels ( τ max = 75 %, 70 %, 60 %, 50 %, and 40 % of the static ultimate strength). The results showed that delamination was the predominant failure mode, as confirmed by scanning electron microscopy (SEM). The experimental fatigue limits were approximately 22.4 MPa for R τ = -1 and 28.0 MPa for R τ = 0.1. A statistical analysis based on the two-parameter Weibull distribution was used to assess the dispersion of fatigue life and construct P-S-N curves for different survival probabilities ( P s = 0.1, 0.368, 0.5, and 0.99). A novel non-linear fatigue damage model was developed by integrating Weibull parameters and survival probability, enabling the prediction of damage evolution curves for varying reliability levels. This model provides a simple yet effective tool for probabilistic fatigue life estimation of fiber-reinforced composites and is well-suited for engineering design applications requiring reliability-based approaches.