Comparative numerical analysis of gap and overlap effect on mechanical properties of variable stiffness composites

Laminates incorporating curvilinear fibers are known as variable stiffness (VS) laminates due to their spatially varying stiffness, determined by the local orientations of the fibers in each ply. VS composites hold significant promise for enhancing structural performance across various industries, including aerospace and automotive engineering. However, the manufacturing process, particularly automated fiber placement (AFP), introduces defects such as gaps and overlaps, which can significantly impact mechanical properties and failure behavior. This study aims to compare two numerical methods for modeling these defects: the defect layer method and the pixelated FE method. A VS laminate with constant curvature fiber path is analysed. The distribution of gaps and overlaps is determined first, and their effects on buckling load and in-plane stiffness are investigated using pixelated FE and defect layer methods. The capabilities and mesh dependency of methods are discussed.