Experimental study of pressurized, foam reinforced, cracked cylindrical aluminum shells

Cracks in pressurized cylindrical shells are subject to stress fields peculiar to the shell geometry and loading conditions which makes them more critical than cracks in flat plates under similar conditions. In order to mitigate the stress field around the crack tips a foam layer is applied to the shell as reinforcement. The effect of this solution on crack behavior is evaluated experimentally. Pre-cracked cylindrical aluminum shells with layers of rigid foam applied to their inner side are tested by subjecting them to cyclic internal pressure. A test bench built especially for the purpose of cyclic testing is described as well as the testing procedure. Results indicate that crack growth rates are significantly reduced and fatigue life is extended by as much as 161%. The application of a foam layer to may help slow down the growth of existing cracks. This solution may prove useful especially in ageing aircraft fuselage structures.