3D static analysis of patched composite laminates using a multidomain differential quadrature method

Fibre Patch Placement (FPP) technology offers the opportunity to overcome the limitations of continuous fibre tape technologies by producing patched composite laminates with variable-stiffness properties that can achieve a load path optimized structural design. Current numerical models based on thin plate mechanics do not capture interlaminar stresses and so fail to predict failure of patched laminates as instigated by such 3D stress fields. This study investigates 3D static performance of patched laminates using Unified Formulation (UF) for beams based on strong- and weak-forms, multidomain differential quadrature method (MDQM) and high-order finite element method (HOFEM) respectively. The study shows that under static loadings, the structural performance of patched laminates is locally influenced by the presence of discontinuities and the intensity of the local effect depends on the laminate sequence as well as the type of loading. Also, the global behaviour of patched laminates under static loadings is not significantly impaired by discontinuities, which supports experimental findings in the literature. Finally, the results of the proposed models prove computationally efficient with about 97% fewer degrees of freedom for MDQM and HOFEM models compared to ABAQUS models of similar accuracy.