Crack deflection by core junctions in sandwich structures

The paper treats the problem of crack propagation in sandwich panels with interior core junctions. When a face–core interface crack approaches a tri-material wedge, as it may happen at a sandwich core junction, two options exist for further crack advance; one is for the interface crack to penetrate the wedge along the face–core interface, and the second is deflection along the core junction interface. Crack deflection is highly relevant and a requirement for the functionality of a newly developed peel stopper for sandwich structures. The physical model presented in this paper enables the quantitative prediction of the ratio of the toughnesses of the two wedge interfaces required to control the crack propagation, and the derived results can be applied directly in future designs of sandwich structures. The solution strategy is based on finite element analysis (FEA), and a realistic engineering practice example of a tri-material composition (face and core materials) is presented.