A geometrically nonlinear forced vibration analysis of circular cylindrical sandwich shells with open/closed cellular core using higher-order thickness and shear deformation theory is presented. The proposed sandwich shell comprises two thin face-sheets perfectly bonded to a functionally graded porous core. The face-sheets are made of carbon nanotubes (CNTs) reinforced composites. Three different types of porosity distribution, including two non-uniform and a uniform variation through the thickness, are considered. The effective mechanical properties of the core material, having open cells or closed cells, are determined using the Gibson and Ashby model. The rule-of-mixture, which includes efficiency parameters to account for scale-dependent properties of nanocomposite media, is adopted to obtain the mechanical properties of the face-sheets. The in-plane and transverse displacements of a generic point are assumed as a third and fourth-order polynomials of the through-the-thickness coordinate. The model is derived within the framework of an equivalent single layer (ESL) theory. Hamilton's principle is employed to obtain the nonlinear governing differential equations and further discretised by adopting the Galerkin method. Finally, the incremental harmonic balance (IHB) method, in conjunction with the arc-length continuation method, is used to solve the nonlinear system of coupled ordinary differential equations and compute the frequency-amplitude response. An extensive numerical study is carried out to examine the effects of the porosity coefficient, porosity distribution, core-to-face ratio and the volume fraction of CNTs in the face-sheets on the frequency-amplitude response of circular cylindrical sandwich shells.

提出了使用高阶厚度和剪切变形理论的具有开/闭蜂窝芯的圆柱形夹心壳的几何非线性受迫振动分析。所提出的夹心壳包括两个薄面板，它们完美地结合到功能分级的多孔核上。面板由碳纳米管 (CNT) 增强复合材料制成。考虑了三种不同类型的孔隙度分布，包括两种非均匀分布和整个厚度的均匀变化。使用 Gibson 和 Ashby 模型确定具有开孔或闭孔的芯材的有效机械性能。采用混合规则来获得面板的机械性能，其中包括考虑纳米复合介质的尺度相关特性的效率参数。通用点的平面内和横向位移被假定为厚度方向坐标的三阶和四阶多项式。该模型是在等效单层 (ESL) 理论的框架内导出的。利用Hamilton原理得到非线性控制微分方程，并采用Galerkin方法进一步离散。最后，采用增量谐波平衡(IHB)法，结合弧长延拓法，求解非线性耦合常微分方程组，计算频幅响应。进行了广泛的数值研究，以检查孔隙度系数、孔隙度分布、