Buckling analysis of angle-ply multilayered and sandwich plates using the enhanced Refined Zigzag Theory

The recent enhancement of the standard Refined Zigzag Theory (RZT), herein named the enhanced Refined Zigzag Theory (en-RZT), has extended the range of applicability of the RZT to angle-ply multilayered and sandwich plates. The aim of the present investigation is to assess the numerical performances of the en-RZT for the buckling analysis of angle-ply multilayered and sandwich rectangular plates under in-plane normal loads. The linearized stability equations are obtained using the Ritz method in conjunction with the principle of virtual work, by means of Gram–Schmidt orthogonal polynomials. In order to assess the accuracy of the en-RZT, buckling loads of angle-ply laminated and sandwich plates are evaluated and compared with the numerical results available in open literature. The numerical investigation highlights the high accuracy of the en-RZT in predicting buckling loads. The study contains a parametric analysis aimed to investigate the influence of various design parameters, such as plate aspect ratio, thickness, lamina orientations, in-plane load combinations and boundary conditions on the buckling loads

Static Response and Buckling Loads of Multilayered Composite Beams Using the Refined Zigzag Theory and Higher-Order Haar Wavelet Method

The paper presents a review of Haar wavelet methods and an application of the higher-order Haar wavelet method to study the behavior of multilayered composite beams under static and buckling loads. The Refined Zigzag Theory (RZT) is used to formulate the corresponding governing differential equations (equilibrium/stability equations and boundary conditions). To solve these equations numerically, the recently developed Higher-Order Haar Wavelet Method (HOHWM) is used. The results found are compared with those obtained by the widely used Haar Wavelet Method (HWM) and the Generalized Differential Quadrature Method (GDQM). The relative numerical performances of these numerical methods are assessed and validated by comparing them with exact analytical solutions. Furthermore, a detailed convergence study is conducted to analyze the convergence characteristics (absolute errors and the order of convergence) of the method presented. It is concluded that the HOHWM, when applied to RZT beam equilibrium equations in static and linear buckling problems, is capable of predicting, with a good accuracy, the unknown kinematic variables and their derivatives. The HOHWM is also found to be computationally competitive with the other numerical methods considered

An Improved Shear-Deformation Theory for Moderately Thick Multilayered Anisotropic Shells and Plates

The general linear equations governing the motion of moderately thick multilayered anisotropic shells are derived by making use of the principle of virtual work in conjunction with an a priori assumed displacement field. The assumed displacement field is piecewise linear in the u and v components and fulfills the static and geometric continuity conditions between the contiguous layers; furthermore, it takes into account the distortion of the deformed normal. Shear and rotatory inertia terms have also been considered in the formulation. Particularization of the resulting equations to the flat multilayered anisotropic plates is straightforward; thus, only the final expressions are given. The proposed approach gives, as particular cases, the linear equations of motion of the classical shells theory based on the Kirchhoff-Love kinematic hypothesis and those of the shear deformation theory for which it is assumed that the deformed normal do not distort.</jats:p