Influence of the boundary relaxation on the flutter and thermal buckling of composite laminated panels

An effective method is proposed to investigate the influences of the boundary relaxation on the supersonic flutter and thermal buckling characteristics of composite laminated panels. The relaxed boundary of the panel is simulated by a set of springs, and the degree of the boundary relaxation is evaluated by adjusting the stiffness of the boundary constraint springs. By employing the characteristic polynomial series as the admissible functions, the Rayleigh-Ritz method is used to calculate the natural frequencies and mode shape functions of the composite laminated panels with relaxed boundary. The supersonic piston theory is employed to determine the aerodynamic loading. The equations of motion of the structure are established by Hamilton's principle. The concept of the relaxation parameter for evaluating the degree of the boundary relaxation is proposed. The flutter and thermal buckling bounds of the laminated panels are validated by comparing the present results with the reference results reported in the literature. Several numerical examples are analyzed, and parametrical investigations with respect to the ply angle and the aspect ratio are performed. Furthermore, the influences of the boundary relaxation on the flutter and thermal buckling bounds of the composite laminated panels are also examined and discussed. (c) 2020 Elsevier Masson SAS. All rights reserved.