Since the multi-layered structures are widely used nowadays, and due to interesting applications of cylindrical shells, this study is dedicated to analyzing free vibrational behaviors of functionally graded saturated porous micro cylindrical shells with two nanocomposite skins. Based on Biot's assumptions, constitutive relations for the core are presented and effective properties of the skins are determined via the rule of mixture. A sinusoidal theory is used to capture the shear deformation effects, and to account for the scale effects, the modified couple stress theory is employed which suggests a material length-scale parameter for predicting the results in small-dimension. With the aid of extended form of Hamilton's principle for dynamic systems, differential equations of motion are extracted. Fourier series functions are used to obtain natural frequencies and after validating them, a set of parametric studies are carried out. The results show the significant effects of porosity and Skempton coefficient, pores placement patterns, CNTs addition and distribution patterns, temperature variations, material length-scale parameter and viscoelastic medium on the natural frequencies of the microstructure. The outcomes of this work could be used to design and manufacture more reliable micro cylindrical structures in thermo-dynamical environments.

由于多层结构现在被广泛使用，并且由于圆柱壳的有趣应用，本研究致力于分析具有两个纳米复合表皮的功能梯度饱和多孔微圆柱壳的自由振动行为。基于Biot的假设，提出了核心的本构关系，并通过混合规则确定了皮肤的有效特性。正弦理论用于捕捉剪切变形效应，并考虑尺度效应，采用修正的耦合应力理论，该理论提出了用于预测小尺寸结果的材料长度尺度参数。借助动态系统的Hamilton原理的扩展形式，提取了运动微分方程。傅里叶级数函数用于获得固有频率，并在对其进行验证后，进行一组参数研究。结果显示了孔隙率和 Skempton 系数、孔隙布置模式、CNT 添加和分布模式、温度变化、材料长度尺度参数和粘弹性介质对微结构的固有频率的显着影响。这项工作的成果可用于在热力学环境中设计和制造更可靠的微圆柱结构。材料长度尺度参数和粘弹性介质对微观结构固有频率的影响。这项工作的成果可用于在热力学环境中设计和制造更可靠的微圆柱结构。材料长度尺度参数和粘弹性介质对微观结构固有频率的影响。这项工作的成果可用于在热力学环境中设计和制造更可靠的微圆柱结构。