Adaptive Composite Materials with Shape Memory Alloy Actuators for Cylinders and Pressure Vessels

An investigation of adaptive hybrid composite cylinders utilizing active Shape Memory Alloy (SMA) composite layers for use in high-pressure vessel applications is presented. An analytical analysis using a linear elastic composite cylinder formulation shows that adapative SMA elements in a composite cylinder can be used to actively reduce peak tensile hoop stresses in the composite cylinder inner walls. Lower peak hoop stresses are produced by using the active SMA elements to create a compound cylinder effect. Significant reductions in peak tensile stresses can be accomplished using the adaptive compound cylinder effect. The resulting hoop stresses in the thickwall composite are also more efficiently loaded through-out the cylinder wall thickness. With the adaptive hybrid composite materials, high-pressure composite cylinders can be produced which have lower levels of radial expansion. A model for the adaptive composite material cylinder and representative stress states for various composite materials is presented. Parametric studies were performed to demonstrate the utility of the adaptive composite cylinder concept for various composite materials and pressure vessel configurations.