Application of total fatigue life model to T700 carbon/vinyl ester composite

A fracture mechanics based total fatigue life model using the methodology proposed previously by the authors was applied to T700 carbon/vinyl ester composite laminate for marine applications. The model included the delamination growth in subcritical, linear, and unstable domains. The increasing fracture resistance effect as the delamination grows was included in the model. Mode-I fracture test was conducted to obtain the fracture resistance GIR as a function of delamination growth. Fatigue onset life test was conducted to determine the threshold energy release rate GIth. Constant amplitude cyclic opening displacement fatigue test with displacement ratio R = 0.1 was conducted to establish the delamination growth rate, da/dN, as a function of maximum cyclic energy release rate normalized by fracture resistance, GImax/GIR. The total life equation was generated and the constants in the equation were determined. The equation fits the test data very well in both subcritical and linear domains while gives limiting solution in unstable domain, because of lack of test data in this domain.