OPTIMUM DESIGN OF FRP LAMINATED PLATES UNDER AXIAL COMPRESSION BY USE OF THE HESSIAN MATRIX.

The optimization technique of the buckling eigenvalue of FRP laminated plates is presented on the basis of the Hessian matrix. The fiber orientation is taken as design variable. The buckling eigenvalue problem is dealt with by the finite element method. The rates of change of the eigenvalue up to the second order are evaluated with the aid of the second order perturbation technique in order to constitute the Hessian matrix which is used to determine the changes of the design variables needed to maximize the eigenvalue approximately. The procedure of such approximation is to be repeated until the eigenvalue converges to the largest value. The numerical analyses with respect to Boron/Epoxy laminated plates under axial compression show that optimization, that is, maximization of the lowest buckling eigenvalue is made possible by use of the Hessian matrix.