Weakening effects of internal part-through elliptic holes in homogeneous and laminated composite plates

A C0-type triangular composite plate element, based on the assumptions of transverse inextensibility and layer-wise constant shear-angle theory (LCST) is employed to analyze an edge-loaded laminated plate weakened by an internal (or embedded) part-through elliptical hole. A homogenous isotropic plate weakened by a similar part-through elliptical hole can be analyzed as a special case of the above. Numerical results for a cross-ply laminate compromised by the presence of an embedded part-through elliptical hole indicate the existence of severe cross-sectional warping in the vicinity of the hole and plate boundaries. Furthermore, three-dimensional nature of the stress concentration factor in the neighborhood of the internal part-through elliptic hole boundary is clearly exhibited. Besides, very high stress concentration factors are found in the layer weakened by the part-through hole. Finally, for a cross-ply laminate compromised by the presence of an embedded part-through elliptic hole in the middle layer, in addition to the singularity at the circumferential line of intersection of the part-though elliptic hole with the material of the middle layer in the form of a circumferential bimaterial interface corner, there is a free-edge singularity at the bimaterial interface at the plate boundaries. These two stress singularities interact so that the effect of the part-through hole never dies down. This is unlike what is shown for a homogeneous isotropic plate weakened by the same part-through hole.