Curvature Effect on Fracture Toughness of Cracked Cylindrical Shells Bonded with Patches

Abstract

Adhesively bonded patch repair has been widely used as an efficient and economical method to extend the service life of cracked structural components. Most of the currently available analysis methods and empirical databases for composite bonded patch repair to flat structures are computationally efficient and easy to use. However, the current knowledge on composite bonded repair for flat structures cannot be directly applied to curved repairs. A novel adhesive element developed by the authors in conjunction with a shell element is employed to investigate the fracture toughness at the crack tip of a cracked cylindrical shell bonded with a composite patch. To validate the present finite element model for curved composite patch repairs, the stress intensity factors in a flat composite patch repair are first computed by the strain energy release rate analysis method and compared with those available in the literature. For the curved patch repairs, a full three-dimensional finite element analysis is also conducted to validate the proposed numerical model. Some selected numerical examples are given to demonstrate the effect of curvature on the fracture toughness of a cracked cylindrical shell bonded with a composite patch subjected to different types of loading.