Fatigue delamination growth in carbon fibre-reinforced aluminium laminates

An experimental study was conducted to examine the fatigue delamination growth in carbon fibre-reinforced aluminium laminates (CARALL) under cyclic loading. The growth rate of cyclic delamination between the aluminium sheets and the fibre/epoxy composite core could be related to the effective strain energy release rate (G(max) - G(th)) by a Paris type equation, dD/dN = c(G(max) - Gth)(m) where c and m are fitting constants. The threshold energy release rate G(th) could be separated into two terms, Gth(0) and G(r). It was shown that G(r) could be related to the strain energy release rate solely due to thermal residual stresses in the laminate, while G(th) might represent a parameter related to the intrinsic interfacial characteristics. Interestingly, the three constants c, m and G(th)(0) were found to be independent of the volume fraction of carbon/epoxy and the magnitude of thermal residual stress. Therefore, once the constants c, m and C-th(0) were determined, the fatigue delamination growth in the hybrid laminate with various carbon/epoxy contents and/or thermal residual stresses could be predicted readily by this empirical equation.