The Damage Criterion Affecting Life Prediction of Fiber-Reinforced Al–Li Alloy Laminates Under Spectrum Loading

Abstract

Fiber metal laminates, as the new generation of aircraft structural materials, are widely concerned by material researcher. This paper presents a study on the life prediction problems of fiber-reinforced Al–Li alloy laminates under spectrum loading by applying the cumulative damage and residual strength models. Firstly, fatigue life performance of the laminate materials is tested under different loading cases. Then, the most advanced damage accumulation and residual strength models are summarized, which is applied to composite laminates. Some models are directly abandoned because the data needed for fitting model cannot be obtained by this experiment or the model formulation is prevented directly to the application for the spectrum blocks with free loading. Meanwhile, a cumulative damage model considering residual strength is modified accordingly based on the characteristics of life prediction under spectrum loading. To study the impacts of these models on the fatigue life prediction for fiber reinforced Al–Li alloy laminate under spectrum loading, the predicted accuracy of these models will be compared by applying them to life prediction problems of 2/1 laminate and 3/2 laminate. Results show that compared with other models, modified model improves the prediction accuracy especially for 3/2 laminate.