Vibration analysis of multi-directional functionally graded nanoplates with initial geometric imperfection using quasi-3d theory based on an isogeometric approach

In this paper, effects of initial geometric imperfection on free vibration analysis of multi-directional functionally graded nanoplates are studied using an isogeometric approach together with the quasi-3D shear deformation theory. Geometric imperfections may exist inherently in nanoplates or purposely created by researchers. These imperfections strongly affect the plates’ natural frequency. The initial geometric imperfection is considered as an initial curvature and modeled by an analytical function in the governing equations of the nanoplate. The effective material properties distribution is stated based on the Mori-Tanaka scheme, which in addition to the thickness of the plate, also changes in the in-plane directions. A four-variable quasi-3D theory with new distribution function is proposed. Based on Hamilton’s principle, a weak form of free vibration problem for nonlocal plates is derived. These discrete systems of equations are solved using an isogeometric approach. The accuracy of the present study was verified by comparing the results with those given in published papers. Present results indicate the importance of various parameters, especially imperfection amplitude, and material indexes in all directions, on the free vibration behavior of FG nanoplates.