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Abstract

The aim of this research is first to model the degradation of the elastic modulus of quasi-isotropic [0/90/ ±45]₂ _s graphite/epoxy centrally notched composite lam inates subjected to tension-tension (T-T) fatigue tests. Then we can predict the fatigue life in terms of elastic modulus as a non-destructive parameter of failure criterion and express the residual strength by using the elastic modulus degradation model. Extensively, the concept of cumulative damage is adopted to expand these models for wide applications to any sequence of loading spectrum instead of the constant stress amplitudes. These models have been modified from the existing models, they possess the features of accuracy, sim plicity and applicability. Basically, part of them are verified satisfactorily in comparison with the experimental data. They still have sound theoretical bases and simply applicable to engineering problems.

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Fatigue Degradation in Centrally Notched Quasi-Isotropic Laminates

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