A nonlinear shell augmented finite element method for geometrically nonlinear analysis of multiple fracture in thin laminated composites

A nonlinear shell augmented finite element method (NS-AFEM) is proposed in this paper to account for the multiple fractures and their interactive evolutions in thin laminated composites with large deformations. This NS-AFEM employed a nonlinear elemental condensation algorithm based on Newton-Raphson method, which explicitly treated the strong discontinuity of a cracked element without the need of extra nodes. In addition, an improved geometrically nonlinear shell-like cohesive zone model (CZM) was developed and integrated into the NS-AFEM to represent the nonlinear fracture processes of composites, including matrix cracking in tension/compression, fiber tensile rupture and fiber compressive kinking, and interface delamination. The high-fidelity simulations in open-hole tension and three-point-bending tests of composite laminates demonstrate that the proposed method is capable of dealing with the geometrically nonlinear coupled crack system in thin laminated composites, which is of particular challenge in other alternative numerical methods.