Design of Thick Composite Cylinders

A simple and efficient design method for thick composite cylinders is presented. Micromechanics and macromechanics are integrated by simple relations and the integrated micro and macromechanics approach has been adopted to enable the designers to instantly study the sensitivity of the micromechanical variables on the final design. The stress analysis is based on 3-dimensional elasticity by considering the cylinder in the state of generalized plane strain. The analysis for both open-ended (pipes) and closed-ended (pressure vessels) cylinders subjected to internal and external pressures and axial load is presented. The failure of the cylinders is predicted by using a 3-dimensional quadratic failure criterion. A degradation model is used to calculate burst pressures and the calculated burst pressures agree very well with the available experimental results, for both thin and thick cylinders. In optimizing multilayer cylinders, the 3-D quadratic criterion enables one to obtain the optimal layer sequence very easily. It is found that the layer sequence is very critical in optimizing, in particular, thick cylinders. In addition, the design parameters and material use efficiency of multilayer closed cylinders subjected to internal pressure have also been studied.