Interlaminar stresses and energy release rates in delaminated orthotropic composite plates

The classical laminated plate theory is applied to calculate the stresses and energy release rate function in symmetrically delaminated orthotropic plates. First, the equilibrium of classical plate forces, moments and interfacial shear stresses is formulated. Second, the displacement continuity between the interface plane of a double-plate model was considered. The governing equation system of the double-plate model consists of ten equations. As an example a delaminated, orthotropic, simply-supported plate subjected to a point force is analyzed. The distribution of the plate forces as well as the interlaminar shear stresses over the uncracked part were determined. Moreover, the mode-II and mode-III energy release rate distributions along the crack front were calculated by the J-integral. The 3D finite element model of the delaminated composite plate was also created. The results indicate a reasonably good agreement between analysis and numerical calculation.