Application Of Design Optimization To Composite Tubes

Composite tubes are often used in both rotary wing and fixed wing applications where low weight is an important design issue. In this paper, the failure of such tubes, under axial compressive loading, is addressed using design optimization and sensitivity analysis procedures. Thin-walled tubes made of symmetric orthotropic laminates with several different wall thicknesses are considered. Using formal optimization techniques, the critical buckling load of the tube is maximized, thereby prolonging the life of the tube, by varying tube radius and individual ply orientations. Constraints are imposed on the longitudinal, normal and in-plane shear stresses of each ply. Results are presented for a Graphite/Epoxy (T300/5208) composite tube with symmetric ply arrangements. The procedure yields significant improvements of the critical buckling load.