DESIGN SENSITIVITY ANALYSIS OF AN ANTISYMMETRIC ANGLE-PLY LAMINATE

Abstract

Sensitivity of an optimally designed antisymmetric angle-ply laminate is investigated to determine the effect of variations in the design variables on the performance of the structure. The laminate is optimized with the objectives of minimizing the maximum dynamic deflection and/or maximizing the eigenfrequency of a given mode. The design variables are the fiber orientations of the individual layers and the optimum point is determined by solving a nonlinear mathematical programming problem. In the case of multipurpose problems, the laminate is optimized with respect to a given objective subject to a constraint, and such problems are solved by a penalty function technique. The formulae for first order sensitivities are derived and applied to some example problems. Global results on the sensitivities are obtained by solving a programming problem in a given sensitivity radius. The design problems, expressed in the form of inequality constraints, are dealt with by the use of performance contours. Numerical results indicate that the sensitivity of a composite structure can be reduced by increasing the number of layers that compose the structure.