Energy Release Rate and Mode Partitioning of Face/Core Debonds under Bending and Shear Based on an Elastic Foundation Approach

Abstract

Closed form expressions for the energy release rate and mode partitioning of face/core debonds in sandwich composites, which are loading in shear and bending, are derived. This is a novel solution based on an elastic foundation approach, and includes the deformation of the substrate (core and bottom face) in addition to that of the top face. In this approach, the sandwich beam is considered as having a “debonded” section, where the debonded top face and the substrate (core and bottom face) are free and a “joined” section, where a series of springs (elastic foundation) exists between the top face and the substrate. The elastic foundation analysis is comprehensive and is done for a general asymmetric sandwich construction. The closed form expression for the energy release rate is derived by evaluating the Jintegral. The mode partitioning definition is based on the transverse and axial displacements at the beginning of the elastic foundation (“debond tip”). A specialization to the Single Cantilever Beam (SCB) specimen is also presented. The results are compared with finite element results and show very good agreement.