Narrow Results

Based on the variational differential quadrature (VDQ) method, the bending and buckling characteristics of circular plates made of functionally graded graphene origami-enabled auxetic metamaterials (FG-GOEAMs) are numerically studied in this paper. It is considered that the plate is composed of multiple GOEAM layers with graphene origami (GOri) content that changes in layer-wise patterns. The results from genetic programming-assisted micromechanical models are also employed in order to estimate the material properties. The plate is modeled according to the first-order shear deformation plate theory whose governing equations are obtained using an energy approach in the context of VDQ technique. The governing equations are given in a new vector-matrix form which can be easily utilized in coding process of numerical methods. By means of VDQ matrix differential and integral operators, the governing equations are discretized and solved to calculate the lateral deflection and critical buckling load of plates under various boundary conditions. Selected numerical results are presented to investigate the influences of boundary conditions, GOri content, folding degree and distribution pattern on the buckling and bending behaviors of FG-GOEAM plates.

This paper aims to investigate the imperfection sensitivity of the post-buckling behavior and the free vibration response under pre- and post-buckling of nanoplates with various edge supports in the thermal environment. Formulation is based on the higher-order shear deformation plate theory, von Kármán kinematic hypothesis including an initial geometrical imperfection and Gurtin–Murdoch surface stress elasticity theory. The discretized nonlinear coupled in-plane and out-of-plane equations of motion are simultaneously obtained using the variational differential quadrature (VDQ) method and Hamilton’s principle. To this end, the displacement vector and nonlinear strain–displacement relations corresponding to the bulk and surface layers are matricized. Also, the variations of potential strain energies, kinetic energies and external work are obtained in matrix form. Then, the VDQ method is employed to discretize the obtained energy functional on space domain. By Hamilton’s principle, the discretized quadratic form of nonlinear governing equations is derived. The resulting equations are solved employing the pseudo-arc-length technique for the post-buckling problem. Moreover, considering a time-dependent small disturbance around the buckled configuration, the vibrational characteristics of pre- and post-buckled nanoplates are determined. The influences of initial imperfection, thickness, surface residual stress and temperature rise are examined in the numerical results.

In this work, the nonlinear primary resonance of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) circular cylindrical panels is numerically studied. The FG-CNTRC cylindrical panels under the radial harmonic loading are modeled on the basis of the hyperbolic shear deformation shell theory (HSDST). The von Kármán hypothesis is employed to incorporate geometric nonlinearity into mathematical modeling. After representing the kinetic and strain energies and the external work in matrix forms (in terms of displacement vector), the variational differential quadrature (VDQ) method is utilized to obtain the discretized form of the energy functional on the space domain. Then, the nonlinear governing equations are achieved via Hamilton’s principle. In the next step, a multistep numerical solution approach is employed to illustrate the influences of geometrical parameters, subtended angle, CNTs distribution scheme and volume fraction on the primary resonant characteristics of FG-CNTRC cylindrical panels. The results are provided for the panels with clamped and simply-supported boundary conditions (BCs).