Thick-walled composite cylinders with optimal fiber prestress

A thick-walled composite cylinder consisting of many different cylindrically orthotropic layers is loaded by uniform, axisymmetric surface tractions and by piecewise uniform eigenstrains in the layers. A theoretical framework is established for evaluation of internal stress fields. An optimization procedure is implemented to find eigenstrain distributions that adjust the stresses in the layers to selected levels, while allowing the application of certain ranges of fiber prestrain magnitude to reduce fiber waviness. A particular fabrication process that utilizes fiber prestress as a source of the layer eigenstrains is analyzed, and a distribution of the fiber prestress forces is found that produces a desired distribution of both hoop and axial stresses in the cylinder wall. Both mandrel stiffness and the chosen prestress magnitude in the first layer influence the distribution. It is shown that application of a high fiber prestress that is constant through the wall thickness can be harmful as it may generate very high hoop stress gradients. Copyright (C) 1996 Elsevier Science Limited