<title>Adaptive composite materials with shape memory alloy actuators for cylinders and pressure vessels</title>

Abstract

An important development in future aerospace applications is the use of thick-wall composite material high-pressure vessels. While polymer matrix composite vessels are already widely used in low- pressure applications, because of reliability and fabrication issues, composite materials have not found use in high-pressure applications. Replacing current steel pressure vessel designs with polymer matrix composite pressure vessels for high pressure applications will yield significant weight reductions. High- pressure composite pressure vessels can reduce the size and weight of fuel, hydraulic, and auxiliary systems in aerospace vehicle applications. Presented here is an investigation of adaptive hybrid composite cylinders utilizing active shape memory alloy (SMA) composite layers for use in high-pressure vessel applications. An analytical analysis using an elasticity formulation shows that the adaptive composite cylinders can carry greater pressures with thinner walls than conventional composite and metal cylinders. A more reliable pressure vessel design is attained due to lower peak stresses in the adaptive composite material vessels. With the adaptive hybrid composite material concept, cylinders which can carry greater pressure with less radial expansion can also be produced. A model for the adaptive composite material cylinder and representative stress states for various composite materials is presented.