Abstract
In this paper, we extended a recently developed augmented finite element method (A-FEM) to account for the complicated progressive damage processes in laminated composites, which are of orthotropic nature and typically develop multiple types of cracking systems including intra-ply matrix/fiber splitting, fiber rupture in tension and/or kinking in compression, and inter-ply delamination. The orthotropic A-FEM represents all of these major damage modes with improved nonlinear cohesive zone models (CZMs) that explicitly consider the asymmetric tension- and compression-responses. A rigorous verification and validation process demonstrates that the developed orthotropic A-FEM can adequately account for the initiation and propagation of various types of cracks and their coupled evolution under complex stress environments. A-FEM predictions to progressive damage processes in several multidirectional notched and un-notched laminates, including the initiation of multiple cracks and their nonlinearly coupled progression with delaminations all the way up to the final, catastrophic failure, are all in excellent agreement with experimental measurements and observations.
