Optimization of bent composite cylinders

Abstract A circular thin-walled cylinder subject to bending is studied. The optimal radius, wall thickness, and lay-up is obtained under a buckling constraint similar to that of the NASA Space Vehicle Design Criteria, and a global bending stiffness constraint. The lay-up is restricted to symmetric laminates but otherwise with complete freedom in the lay-up angle variation through the thickness, which is obtained by using lamination parameters as design variables. By neglecting the influence of geometry and stiffnesses on the knock-down factor for buckling, the optimal lay-up is found to be independent of the requirements of buckling strength and stiffness, i.e. all cylinders of a specific material will have the same optimal lay-up.