Crack deflection analyses of different peel stopper designs for sandwich structures

This paper relates to a newly developed peel stopper concept for sandwich structures. The proposed concept is a specially designed core insert, which has the ability to confine face sheet debonding/delamination (peeling) by deflecting a delamination crack front away from the face/core interface into the bulk of the sandwich core, and thereby constraining the debonding/delamination to a limited prescribed area. In this paper various peel stopper designs are analysed for their ability to deflect cracks away from propagating along a face–core interface. The crack deflection ability of the studied peel stopper designs leads to design guidelines, which describes the minimum requirements regarding the relation between the two interface toughnesses. The analysis further reveals that compliant peel stopper wedges are preferred because they lead to the lowest interface toughness ratio requirement. This has been confirmed through an experiment with a sandwich beam subjected to three-point bending loading. The experiment has shown that the ability of a peel stopper to deflect cracks is highly dependent on the stiffness of the wedge.