Analytical Model for Single-Side Patch Design of Composite Repair

Abstract

A study was undertaken to develop an analytical model that can be used for patch designs of cracked plates using the single-side composite patch. The model helps to select a patch material (i.e., elastic modulus of the material) and the patch thickness in order to reduce the Strain Energy Release Rate (SERR) at the crack tip. In other words, in order to achieve the desired SERR using the single-side patch, the analytical model can be utilized to find a proper patch material and patch dimensions for the given cracked plate if the plate modulus and thickness as well as the crack size are known. The model is based on the axial and bending stresses of the single-side strap joint, and those stresses are related to the SERR at the crack tip of a plate with a single-side patch repair. In order to verify the analytical model, finite element analyses were conducted to determine stresses as well as SERR in many different patched plates. The numerical study confirmed the validity of the analytical model to predict the reduced SERR resulting from the single-side patch repair.