Quantifying the sensitivity of plate aspect ratio and edge boundary conditions on CFRP plate impact and post impact residual strength

Much literature exists on composite plate impact damage and residual strength post impact, but there is limited work which systematically examines how plate behaviour alters with plate aspect ratio and edge rotational restraint. Through simulation of composite stiffened plates under low velocity impact and Compression After Impact loading, the presented work demonstrates that laminate impact response and subsequent residual strength is highly sensitive to both plate aspect ratio and boundary conditions. Increasing edge restraint for low aspect ratio plates results in a moderate increase (up to 13.3%) in residual strength. Conversely, for higher aspect ratio plates (representative of aircraft stiffened panel components), the same change in edge restraint results in an equivalent decrease in residual strength (up to 13.0%). In particular, the interaction between impact induced damage and the onset of plate buckling observed in higher aspect ratio plates, and the subsequent effect on predicted residual strength, is not captured when examining low aspect ratio plates utilised in traditional material coupon testing practices.