MINIMUM WEIGHT DESIGN OF LAMINATED COMPOSITE PLATES SUBJECT TO STRENGTH CONSTRAINT

The minimum weight of laminated composite plates subject to strength a nd side constraints is studied via a constrained global optimization t echnique. The first-ply failure load that is treated as the strength o f a laminated plate is determined by using a shear deformable finite e lement and one of the several commonly used phenomenological failure c riteria. The optimal layer group parameters (fiber angles and thicknes ses of layer groups) of the laminated composite plate are determined V ia the proposed constrained global optimization technique for attainin g the global minimum weight of the plate and satisfying the imposed co nstraints. A number of examples of the minimum weight design of symmet rically laminated composite plates with various aspect ratios, differe nt number of layer groups, and different boundary conditions are given to illustrate the applications of the present constrained global opti mal design method. The effects of the failure criteria on the optimal design parameters are also investigated via the examples. Finally, exp erimental investigation of the capability of the present method in obt aining global optima is performed. Failure tests of a number of graphi te/epoxy laminates designed by different methods are performed, and th e superiority of the present method over the other methods is demonstr ated via the test results.