Three-dimensional nonlinear analyses of scarf repair in composite laminates and sandwich panels

A special-purpose analysis tool based on the finite element method is presented for parametric design studies of composite laminates and sandwich panels with scarf repairs. This design tool provides the complete three-dimensional stress and strain fields in scarf-repaired panels without any requirements on the nature of the lamination and the type of loading. The adherends are modeled using a plate element based on a higher-order single-layer theory, and the adhesive is modeled using a solid element. The higher-order nature of the plate theory makes it suitable for analyzing thick laminates and sandwich panels comprised of numerous plies. The model takes into account geometric nonlinearity in the adherends and assumes a bilinear stress-strain relationship for the adhesive. The responses of composite laminates with single- and double-sided repairs and sandwich panels with both full and partial repairs of the top face sheets are investigated.