POSTBUCKLING RESPONSE OF PIECE-WISE UNIFORM TAILORED COMPOSITE PLATESIN COMPRESSION

Tailoring, or precisely specifying, the types, amounts, orientations a nd locations of composite materials in a structure to satisfy specific performance requirements is inherent to the design of efficient compo site structures. A simple piece-wise uniform stiffness tailoring conce pt has previously been shown to increase compressive buckling loads of plates by as much as 138% to 195%, depending on the baseline uniform laminate. The question arises as to what benefits, it any, exist for p lates tailored in this way when loaded in the postbuckling regime. Thi s paper presents predictions for global measures of the postbuckling r esponse of plates loaded in compression which have been tailored to ma ximize the initial buckling load. The analysis shows that postbuckling loads at failure can be increased by 130% to 150% by tailoring. The e dge strain at first-ply failure is not significantly affected by tailo ring. Postbuckling membrane secant and tangent stiffnesses are much hi gher for tailored plates than for uniform plates. Out-of-plane postbuc kling deflections are shown to be much smaller at a given load level w hen tailoring is employed. The initial buckling mode shape and the man ner in which postbuckling mode changes take place are strongly affecte d by tailoring. Thus, with this design approach, optimization for init ial buckling can provide concurrent benefits in postbuckling response. This improved performance suggests that the skin plate of stiffened c omposite panels could be tailored using the current approach to signif icantly improve the postbuckling performance of stiffened panels.