Bending, free vibration and buckling of functionally graded carbon nanotube-reinforced sandwich plates, using the extended Refined Zigzag Theory

The paper presents an application of the extended Refined Zigzag Theory (eRZT) in conjunction with the Ritz method to the analysis of bending, free vibration and buckling of functionally graded carbon nanotube-reinforced (FG-CNTR) sandwich plates. Two stacking sequences are taken into consideration: sandwich panels with a homogeneous core and functionally graded face-sheets and sandwich panels with homogeneous face-sheets and a functionally graded core. After validating the convergence characteristics and the numerical accuracy of the developed approach using orthogonal and non-orthogonal admissible functions, a detailed parametric numerical investigation is carried out. Bending under bi-sinusoidal and uniform transverse pressure, free vibration and buckling loads under uniform in-plane uniaxial, biaxial and shearing loadings of FG-CNTR sandwich plates are studied. Numerical results for square and rectangular FG-CNTR sandwich plates under various combinations of geometry (core-to-face sheet thickness ratio and side to thickness ratio), different set of boundary conditions, CNTs volume fraction and grading laws are presented and discussed in detail. It is concluded that the eRZT predicts the response for static, stability and free vibration problems more accurately than first-order (FSDT) and third-order (TSDT) shear deformation theories, also for FG-CNTR sandwich plates.