A nested three-dimensional (3D) material and structural modeling framework is proposed for nonlinear damage analysis of fiber-reinforced composite structures. Micromechancial and damage models for different composite material systems, such as unidirectional fiber reinforced polymeric (FRP) composites, woven and braided fabrics, can be directly integrated within the components: elastic-degrading continuum damage models for each of the matrix and fiber periodic medium, and a 3D sublaminate model for a repeating ply stacking sequence. The beyond initial failure. The framework is implemented within a displaced-based 3D nonlinear finite-element code. As a result, progressive damage modeling of composite structures is achieved. This approach allows nonlinear anisotropic response, including strain-softening and damaged elastic unloading behavior. Fiber modes of failure are also recognized, including fiber microbuckling. The overall objective of the proposed research is to enhance understanding of the microstructural properties of heterogeneous materials that strongly influence the global damage response of composite structures.
