MINIMUM WEIGHT DESIGN OF SYMMETRICAL ANGLE-PLY LAMINATES WITH INCOMPLETE INFORMATION ON INITIAL IMPERFECTIONS

An angle-ply laminated plate is optimized with the objective of minimi zing its weight subject to maximum deflection and buckling constraints . The plate has an initial deflection the shape of which is not known a priori, i.e., the initial deflection is not specified in a ''determi nistic'' manner and as such it is ''uncertain.'' The weight is proport ional to the laminate thickness which is minimized taking the ply angl es as design variables and under the least favorable conditions of ini tial imperfections. The convex modeling approach is employed to analyz e the uncertain initial deflection with the uncertain quantities allow ed to vary arbitrarily around their average values subject to the requ irement that these variations are bounded in L-2 norm. The results are given for both single load and multiple load cases and the effect of uncertainty on the optimal design is investigated. It is shown that th e minimum weight increases with increasing level of uncertainty and th e optimal ply angles also depend on the level of uncertainty.