Weight Reduction of Isotropic Cylinders Using Equivalent Compound Cylinders

A monoblock isotropic cylinder can be reduced in weight by replacing material from its outer diameter with a lightweight stiff composite material, such that the resulting compound cylinder has a bore radial displacement per unit of internal pressure equivalent to that of the original monoblock design. This report is a study of the weight savings that can be achieved by using different composite materials to replace isotropic materials in cylindrical pressure vessels. The study contains a derivation of some nondimensional material parameters that can be used to characterize the effectiveness of the composite as a replacement material, including upper bounds on the weight savings that can be achieved. Furthermore, it is shown that these material parameters form the basis for the definition of three general categories of composite replacement materials. The investigation also includes results from the application of the theory to twenty different isotropic composite systems.