Design of Composite Cylinder Fabrication Process

Fiber prestraining is often employed to reduce fiber waviness while fabricating composite cylindrical structures by filament winding or fiber placement. The effect of fiber prestraining on the final residual stress state in a closed-end laminated cylinder fabricated on a steel mandrel is analyzed here. The elements influencing the residual stress state are identified and the corresponding influence functions relating the ply stresses to the fiber prestrain are obtained. The ply residual stresses are evaluated for a constant prestrain distribution in all the layers. An optimization procedure is implemented to find prestrain distributions that produces minimal residual stresses in layers. The role of mandrel stiffness on final residual stress state is also studied by selecting different mandrel thicknesses.