Extension of scaled boundary finite element method for delamination simulations in laminated composites under three-dimensional framework

This work investigates a three-dimensional (3D) Scaled Boundary Finite Element Method (SBFEM) based framework for simulating progressive interlaminar crack growth in laminated composites. A 3D formulation enables modelling of complex geometries with irregular crack fronts. The methodology employs zero-thickness cohesive elements to accurately represent the interlaminar interfaces. Several benchmark case studies were performed, including both pure-mode and mixed-mode fracture, encompassing cases where the crack front undergoes shape variations during crack propagation. The case studies were validated against experimental results and results obtained from other simulation techniques, such as conventional finite element method or analytical models, demonstrating a strong correlation among them. A key novelty of SBFEM explored in this paper is ability to decouple surface and volume discretization. This allows the framework a much higher flexibility in terms of meshing architectures and significantly reduces the number of degrees of freedom (DOFs) needed to accurately solve the problem. It also allows for straightforward local mesh refinement of surfaces in critical regions, such as adjacent to cohesive zone elements. The paper concludes with a discussion of the potential of the proposed approach in advancing the understanding and analysis of fracture phenomena in laminated composites.