A methodology for minimization of composite panels deflections and stresses that uses a time domain nonlinear modal finite element model with two different optimization algorithms (genetic and DB algorithms) is described. The nonlinear modal formulation is based on geometrical nonlinearities rather than material nonlinearities, which does not require updating of the stiffness matrix at each time step, making it extremely time efficient when compared to commercial finite element softwares. Optimization algorithms are implemented in Matlab and can be used either with the finite element code itself or as a post-processing option. The method is applied to rectangular 10-ply symmetrically laminated plates under uniform pressure loads, with simply supported and clamped boundary conditions. The design constraints are based on the Tsai-Wu failure criterion. Results of the optimization using genetic algorithm include the influence of the initial size of population and number of generations. The DB algorithm proposed by the authors is shown to be more effective for the presented examples than the genetic algorithm.