Prediction of tensile fatigue life under temperature environment for unidirectional CFRP

A method for prediction of fatigue strength under temperature environment w as proposed for polymer composites and its validity was confirmed for the f lexural fatigue strength of satin-woven CFRP laminates and others. This met hod is based upon the four hypotheses: (A) same failure process under const ant strain-rate (CSR), creep, and fatigue loadings, (B) same time-temperatu re superposition principle for all failure strengths, (C) linear cumulative damage law for a nondecreasing stress process, and (D) linear dependence o f fatigue strength upon stress ratio. Data are provided for tensile CSR, cr eep, and fatigue tests at various loading rates, frequencies, and temperatu res in the longitudinal direction of unidirectional CFRP. In this paper, ex perimental verification of the prediction method is discussed for the tensi le fatigue strength of unidirectional CFRP.