The Inclusion of In-Plane Stresses in Delamination Criteria

Delamination is characterized as the failure of the interply resin-rich region. The interply resin layers are modeled and the six component stress state is determined using a finite element analysis. The Modified von Mises Delamination Criterion using both the in-plane and interlaminar stresses is developed and applied to the average stress state within 1.75 ply thicknesses of the edge. The MVMDC shows good correlation to experimental data as well as to other criteria. TheMVMDCis not sensitive to the thickness of the interply resin layer. Instead it is merely the presence of such a layer and the stresses that result in the layer that can indicate delamination failure of a laminate. Thus consideration of the full stress state in the failure of the interply resin layer is valid and indicates the potential for interaction between the in-plane loading and delamination.