Progressive failure analysis of carbon-fiber reinforced polymer (CFRP) laminates using combined material nonlinear elasticity and continuum damage mechanics based on treatment of coupon test

In this paper, predictions of the tensile strength of carbon-fiber reinforced polymer (CFRP) laminate composites are attempted using an improved continuum damage mechanics model with emphasis on the material nonlinearity of the fiber, shear stiffness reductions, the damage contribution of matrix cracks in adjacent layers, and the statistical distribution of the fiber strength due to defects. The Weibull parameter to establish a continuum damage mechanics model was extended to five parameters to satisfy multiscale compatibility and interlamina effects. These five Weibull parameters, which serve as coefficients of a damage evolution function, were investigated by using a statistical model of progressive tensile fiber failure in a composite laminate. The Newton–Raphson method was utilized to formulate a damage-estimation method via a progressive failure analysis procedure. A continuum damage analysis based on the Matzenmiller–Lubliner–Taylor model was revised to add the statistical characteristics of the material strength. The proposed continuum damage mechanics method was also used to solve laminate tension problems with various stacking sequences. The verification test articles include 16- and 20-ply IM7/8552, AS4/8552, and T700/M015 carbon/epoxy composite laminate un-notched and open-hole tensile specimens. The strength prediction of each laminate specimen is presented.