* Corresponding author. Tel.: +98-21-66165516; Fax: +98-21-66000021 E-mail address: fallah@sharif.ir DOI: 10.22075/MACS.2019.16171.1167 Mechanics of Advanced Composite Structures 6 (2019) 65–74 Semnan University Mechanics of Advanced Composite Structures journal homepage: http://MACS.journals.semnan.ac.ir Non-Linear Analysis of Functionally Graded Sector Plates with Simply Supported Radial Edges Under Transverse Loading F. Fallah * , M.H. Karimi Department of Mechanical Engineering, Sharif University of Technology, P.O. Box 11365-9567, Azadi Avenue, Tehran, Iran PAPER INFO ABSTRACT Paper history: Received 2018-10-14 Received in revised form 2019-01-15 Accepted 2019-04-26 In this study, nonlinear bending of functionally graded (FG) circular sector plates with simply supported radial edges subjected to transverse mechanical loading has been investigated. Based on the first-order shear deformation plate theory with von Karman strain-displacement relations, the nonlinear equilibrium equations of sector plates are obtained. Introducing a stress function and a potential function, the governing equations which are five non-linear coupled equations with total order of ten are reformulated into three uncoupled ones including one linear edge-zone equation and two nonlinear interior equations with total order of ten. The uncoupling makes it possible to present analytical solution for nonlinear behavior of FG sector plates with simply- supported radial edges via perturbation technique and Fourier series method. The material properties are graded through the plate thickness according to a power-law distribution of the volume fraction of the constituents. The results are verified by comparison with the existing ones in the literature. The effects of non-linearity, material constant and boundary conditions on bending of an FG sector plate are studied. It is shown that in bending analysis of functionally graded sector plates, linear theory is solely applicable for w/h< 0.2 and is inadequate for analysis of fully simply supported FG sector plates even in the small deflection range. Keywords: Functionally graded Materials First-order shear deformation plate theory Sectorial plate Nonlinear analysis Perturbation technique © 2019 Published by Semnan University Press. All rights reserved. 1. Introduction Functionally graded materials (FGMs) were first introduced in 1984 by material scientists in Japan [1]. These materials are heterogeneous and are made of at least two constituents. Furthermore, their properties vary continuously by gradually changing the volume fraction of the constituent materials along certain directions. They have found many applications in different fields due to their smooth variation in properties including spacecraft heat shields, heat exchanger tubes, biomedical implants, and flywheels [2]. Sector plates have a wide range of engineering applications such as basic structural elements, curved bridge decks, building floor slabs, and steam turbine diaphragms [3]. Therefore, understanding the mechanical behavior of sector plates is necessary. Based on the first-order shear deformation plate theory (FSDT), Ambartsumyan [4] presented an exact analytical solution for bending analysis of isotropic homogenous sector plates with two radial edges simply supported under uniform loading. Cheung and Chen [5] employed the finite strip method for static and dynamic analyses of thin and thick sectorial plates. Lie and Liew [6] adopted the differential quadrature method for a static analysis of annular sectorial plates based on FSDT. Lim and Wang [7] developed relationships between the Mindlin plate results and the corresponding Kirchhoff plate solutions for bending of annular sectorial plates with simply supported radial edges. Based on the FSDT, Jomehzadeh and Saidi [8] presented an exact