Sensitivity of the eigenvalues to the ply angles for composite plate

This paper studies the sensitivity of eigenvalues to ply angles for composite plates. Based on the classicaltheory of the laminated composite plate , the mass mat rix and stiffness mat rix were obtained by using thefinite-element-method and principle of virtual work. The equation between ply angles and stiffness mat rix was determined and by using the perturbation method in dynamic equation , the sensitivities of the eigenvalues to the ply angles were obtained explicitly. Through the numerical example given in the paper , the conclusion was demonst ratedthat the present method has superiority in accuracy compared with the finite difference method.