A novel two-scale progressive failure analysis method for laminated fiber-reinforced composites

A novel, two-scale computational model has been developed to predict the progressive damage and failure responses of fiber-reinforced composite laminates using the material properties at the constituent (fiber and matrix) level. These properties were measured from coupon level tests on a unidirectional lamina of the same material system. In the proposed computational scheme, the macroscale finite element analysis (FEA) was carried out at the lamina level of a 3D laminate model, while micromechanical analysis was implemented concurrently at the subscale to compute the local fields at the fiber and matrix scale. Thus, the influence of matrix microdamage at the microscale manifests as the progressive degradation of the lamina stiffness, resulting in the nonlinear evolution of the stress versus strain response, while the lamina stiffness matrix remains positive-definite. The lamina post-peak strain softening response resulting from catastrophic failure modes including fiber tensile breakage, fiber kinking and matrix cracking, were modeled using the smeared crack approach (SCA). The interlaminar failure due to delamination was accounted for through cohesive elements inserted in-between the layers. The predictive capability of the proposed method is illustrated by comparing the computational results with experiment for three different lay-ups of IM-7/977-3 carbon fiber composite laminates subjected to various loading conditions, including both un-notched and open-hole specimens subjected to remote tensile and compressive loading, respectively.