Maximum fundamental frequency of thick laminated composite plates by a hybrid optimization method

As a first attempt, a combined method is introduced to obtain maximum fundamental frequency of thick laminated composite plates via finding optimum fibers orientation. The governing equations are obtained based on the higher order shear deformation theory (HSDT). The robust and accurate finite element method (FEM) is used to discretize the governing equations. The transferred form of the equations in frequency domain is obtained and the fundamental frequency of the plate is achieved. High sensitivity of the problem with the fibers orientations is shown. To find the optimum fibers orientation of the thick plate a mixed implementable evolutionary algorithm is used. In the proposed genetic algorithms (GAs) base method, particle swarm optimization (PSO) method is added to improve specified percent of GAs population. Applicability and usefulness of the method is demonstrated by solving different examples.