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The aim of the present research is to investigate the nonlinear dynamic and forced vibration of a composite sandwich panel embedded with piezoelectric layers under thermo-harmonic loading. The panel consists of a double-U auxetic honeycomb core made of aluminum alloy and graphene platelet reinforced composite (GPLRC) skins at the top and bottom surfaces. According to Gibson's formula, the effective material properties of facing sheets and double-V auxetic core are considered. The nonlinear equations are obtained by applying Hamilton's principles via von Karman's nonlinear theory and higher-order shear deformation theory (HSDT). The governing equations of motion are solved by employing the differential quadrature method (DQM) and homotopy perturbation method, respectively. The accuracy of the current results has been verified by comparison with others in the literature. Finally, the influence of different parameters such as applied voltage, magnetic potential, temperature rise, different boundary conditions, and geometric parameters of core on the nonlinear frequency-amplitude response of cylindrical panels are analyzed. The numerical results show negative effect of temperature increment, positive influence of ratio of thickness to inclined length, core thickness, amplitudes of segments, considerable effect of the magnetic potential as well as small effect of applied voltage on the nonlinear vibration of sandwich panel. Finally, the important findings of this research indicate that the magnetic potential, amplitude segment, and length to inclined cell rib length have significant effects on nonlinear dynamic deflection and frequencies-amplitude response. Based on the results of this article, designers can develop different parts of aircraft. [ABSTRACT FROM AUTHOR]

In this study, nonlinear aeroelastic instability of a composite sandwich panel subjected to a supersonic airflow and thermal loading is investigated. The sandwich panel is composed of three-phase composites with polymer/Graphene platelet/fiber skins at the top and bottom surfaces and an auxetic honeycombs core layer with a negative Poisson's ratio. The motion equations of the panel within the framework of higher-order shear deformation theory (HSDT) and von Kármán nonlinearity are driven. In addition to Krumhaar's modified supersonic piston, unsteady aerodynamic pressure in the supersonic flow regime is considered. The governing equations of the sandwich panel are derived by implementing Hamilton's principle and solved by the generalized differential quadrature method (GDQM). Validation of the present formulation is assessed by comparing the numerical results with those available in the open literature. Then, the effects of several parameters such as geometric parameters, volume fraction, Mach number, different boundary conditions, yaw angle, and different inclined angles on the nonlinear aeroelastic stability of sandwich panels are examined. Finally, it was found that the ratio of core thickness, inclined angle, and Mach number have significant effects on aerodynamic pressure. [ABSTRACT FROM AUTHOR]

This paper deals with the nonlinear vibration behavior of sandwich panels composed of Graphene platelet reinforced composite (GPLRC) skins and auxetic core embedded with piezoelectric layers subjected to the thermo-magneto-electric loading. The nonlinear equations are obtained by applying Hamilton's principles in the framework of higher-order shear deformation theory (HSDT) and von Karman's nonlinear theory. Linear and nonlinear equations of motion are solved by applying the differential quadrature method (DQM) and homotopy perturbation technique, respectively. In the numerical illustration, at first validation of the present formulation is carried out by comparing the numerical results with those available in the open literature. Then the effects of several parameters such as geometric parameters of auxetic core, applied voltage, magnetic potential, GPL volume fraction, different boundary conditions, and temperature rise on the nonlinear frequency response of sandwich panel are studied. From numerical results, it was concluded that the sandwich panel incorporating auxetic core and piezoelectric layers could increase the magneto-electrical power output. [ABSTRACT FROM AUTHOR]

AbstractThis research has been conducted to analyze the free vibration behavior of a five-layered composite plate with a viscoelastic auxetic core. The plate comprises a viscoelastic auxetic core layer, functionally graded carbon nanotube reinforced composite (FG-CNTRC) interior, and magneto-electro-elastic functionally graded porous (MEE–FGP) exterior skins, which is rested on Winkler–Pasternak foundation. According to the magnetic–electric boundary conditions and Maxwell equations, the electric and magnetic potentials of the plate are determined. The macro-mechanical properties of the auxetic core have been derived based on Gibson’s model; the three-parameter Zener model has also been utilized to describe its viscoelastic behavior. Additionally, the equations of motion of the plate are obtained and solved by using Reddy’s third-order shear deformation theory (TSDT) and the Galerkin method, respectively. Moreover, various aspects of the current research have been validated by comparing the numerical results with those reported in the literature section. Overall, in the numerical result section, the effects of different parameters and conditions such as geometrical parameters, position of the plate’s interfaces of layers (thickness of the core and face layers), various distribution patterns and volume fractions of both CNT and porosity, external work parameters of the MEE skins, boundary conditions, Winkler–Pasternak stiffness coefficients, the relaxation time, and other parameters of the viscoelastic core on the natural frequency and loss factor of the composite plate are represented. [ABSTRACT FROM AUTHOR]