Simple, Conservative Criteria for Buckling and Delamination Propagation in the Presence of Stitching

Abstract

The problem of delamination cracks in laminates that are bridged by stitches is revisited. Analytical solutions for the critical strain for buckling of a bridged, delaminated layer are extended to consider propagation of the delamination crack under in-plane compression in the limit that the crack is long. Numerical estimates for common laminate parameters show that delaminations of interest will not be far from the long crack limit. Therefore, the analytical results should be conservative but not wasteful design guides.