AN EVALUATION OF THE INFLUENCE OF GEOMETRY AND OF MATERIAL PROPERTIESAT FREE EDGES AND AT CORNERS OF COMPOSITE LAMINATES

Characteristic of multilayered structures is the edge-stress problem, where interlaminar shear and normal stresses are responsible for delam ination. Whereas analyses implicitly accounting for the singularity at the edge interface and which prove its existence numerically can be f ound in the literature, analyses which explicitly account for it are l acking. To make up for this deficiency and at the same time to assess the effect of material properties and layer orientation, the slope of inclined edges and the angle at corners, a three-dimensional, finite e lement stress singularity analysis is carried out. A three-dimensional singular wedge element with variable singularity power shape function s based on a displacement formulation is used for this purpose. A pred ictor-corrector procedure is employed to fulfill the stress contact an d traction-free conditions. The present numerical results confirm the existence of the singularity for all the lay-ups investigated. They sh ow a negligible effect of material properties, lay-up and slope at the free edge. On the contrary, a considerable effect of the lay-up and o f the vertex angle is focused at corners.