Analysis of Strength and Residual Stresses in Filament Reinforced Aluminum Cylinders

Abstract

This paper describes a study of aluminum gas cylinders used in underwater manned vehicles. A determination was made of the relative increase in one cycle burst pressure and fatigue life of an existing aluminum gas cylinder when the sidewall was reinforced with fiberglass overwrap and prestressed by over pressurization. Detailed finite-element stress analyses were conducted to determine the operating stresses and also the residual stresses at the end cap-to-cylinder transition section which were a result of plastic deformation during proof testing. Calculated residual stresses were found to be consistent with experimental measurements. It was determined that the filament reinforcement both increased the vessel burst pressure and increased the vessel fatigue life through favorable prestress effects. Results of vessel fatigue and burst tests are presented and are compared with the predicted performance characteristics.