Optimization of Stiffened Laminated Composite Plates With Frequency Constraints

The problem considered in this paper concerns the maximization of frequencies of stiffened laminated composite plates subject to frequency separation constraints and an upper bound on weight. The number of plies of given fiber orientations and the stiffener areas form the two sets of design variables and the problem belongs to the class of nonlinear mixed integer programming ( NMIP) Several efficiency measures are adopted to reduce the computational cost of the optimization process. As a result of these efficiency measures, structural optimization of laminated composite plates using nonlinear mixed integer programming becomes a viable alternative to using the conventional practice of obtaining designs by an ad hoc rounding off of the continuous designs.