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Thermal effect on the pull-in instability of functionally graded micro-beams subjected to electrical actuation, Composite Structures (2014), doi: http://dx.doi.org/10. 1016/j.compstruct.2014.05.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Thermal effect on the pull-in instability of functionally graded micro-beams subjected to electrical actuation Abstract. The thermal effect on the pull-in instability of functionally graded micro-beams under the combined electrostatic force, temperature change and Casimir force is studied based on Euler-Bernoulli beam theory and von Kármán geometric nonlinearity. Take into consideration the temperaturedependency of the effective material properties, the Voigt model and exponential distribution model is used to simulate the material properties of the functionally graded materials (FGMs). Principle of virtual work is used to derive the nonlinear governing differential equation which is then solved using the differential quadrature method (DQM). A parametric study is conducted to show the significant effects of material composition, temperature change, geometric nonlinearity and Casimir force. Keywords:Functionally graded materials; Micro-beam; Temperature change; Pull-in instability; Casimir force * Corresponding author, Ph. D, E-mail address: xljia@cup.edu.cn Tel: +86 10 89733762 IntroductionMicro-Electro-Mechanical Systems (MEMS) can be defined as systems of small dimensions fulfilling a smart function. The devices are typically designed to operate in one or more energy domains due to their unique advantages such as small size, lower power consumption, lower operation cost, increased reliability and higher precision. With MEMS are used more and more widely due to their unique advantages, such as small size, lower power consumption, lower operation cost, increased reliability and higher precision, numerous analytical, numerical and experimental studies have been conducted on the pull-in instability of the MEMS devices [1][2][3][4][5].Most recently, the use of functionally graded materials (FGMs) in MEMS structures has been proposed by Craciunescu and Wuttig [6] and Fu et al. [7], since FGMs offer many advantages including improved stress distribution, enhanced thermal resistance, higher fracture toughness, and reduced stress intensity factors that make them very attractive in many engineering applications [8]. Specially, Witvrouw and his co-workers [9, 10] developed a multilayer polySiGe deposition process for fabricating MEMS structural layers that fulfill all material and economical requirements.Along with the development of technology, MEMS are expected to ...