Predicting the rate-dependent non-linear progressing damage behavior of unidirectional composites from the rate dependent properties of the constituents will enable computational materials-by-design and provide the fundamental understanding of the energy dissipating damage mechanisms. In this study, three micromechanical finite element model of unidirectional glass-epoxy composites have been developed with fiber volume fractions of FVF = 50%, 60% & 70%. In order to model the fiber fracture, each fiber is modeled as an assembly of 2 micron cylindrical segments while a zero thickness cohesive traction law is defined between the segments. A bimodal Weibull tensile strength distribution has been used to stochastically generate the fiber strength distribution. Between the fibers and the matrix, zero thickness fiber-matrix cohesive interfaces have been placed to model the fiber-matrix interphase debonding. Experimentally determined rate dependent non-linear stress-strain behavior of DER353 epoxy resin (Tamrakar 2019) has been used to model the large deformation matrix behavior in conjunction with a rate dependent fiber-matrix interface traction law obtained from S-2 Glass/DER353 micro-droplet experiments & simulations (Tamrakar 2019). Axial tension and punch shear loads have been applied at different loading rates in predicting the rate dependent progressive damage behavior of unidirectional S-2 Glass/DER353 epoxy composites and will presented in detail.
