Multiscale progressive damage analyses for fiber reinforced composites subjected to biaxial loading

A multiscale integrated Finite-Element (FE) and High Fidelity Generalized Method of Cells (HFGMC) micromechanics modeling analysis is proposed to generate failure envelopes for both unidirectional and multidirectional carbon/epoxy composite laminates subjected to biaxial loading conditions. The proposed modeling approach is implemented as a user material subroutine (UMAT) within displacement-based layered FE models, whereby each layer (lamina) is represented by a hexagonal repeating unit-cell (RUC) recognizing the fiber and matrix phases of a lamina at the microstructure. The fiber is considered to behave as an elastic transversely isotropic material. The nonlinear elastic behavior along with the J2-deformation plasticity are used to account for matrix nonlinearity. Failure of a lamina is determined by using both strain-based and stress-based failure theories. The lamina stress and stiffness contributions are eliminated from the FE model in case of a failure. The in-situ mechanical properties and damage parameters of the RUC are determined by calibration using available axial, transverse, and shear experimental responses. The efficiency of the proposed multiscale analysis is demonstrated by a comparison with measured failure envelopes available in the literature.