Radiographic Investigation of the Effects of Ply Modification on Damage Development in Laminates Containing Circular Holes

Abstract

The goal of this research was to evaluate possible damage suppression in multi-directional notched laminates through the use of slightly off-axis longitudinal plies. These `non-traditional' laminates were compared to laminates with 0° longitudinal plies for quasi-isotropic and hard lay-ups, for open hole tension, filled hole tension, and single-shear bearing loadings. In-situ radiographic inspections were performed to evaluate damage initiation, progression, and suppression. In notched tension, the non-traditional laminates were less strong and stiff than their traditional counterparts, but X-ray images clearly showed the suppression of longitudinal splitting and delamination. Under single-shear bearing loads, the non-traditional laminates demonstrated increased bearing resistance compared to traditional laminates, and the non-traditional laminates were less prone to damage in the longitudinal plies.