Hindawi Publishing Corporation Journal of Composites Volume 2013, Article ID 808764, 12 pages http://dx.doi.org/10.1155/2013/808764 Research Article Buckling Analysis of Functionally Graded Material Plates Using Higher Order Shear Deformation Theory B. Sidda Reddy, 1 J. Suresh Kumar, 2 C. Eswara Reddy, 3 and K. Vijaya Kumar Reddy 2 1 School of Mechanical Engineering, R.G.M College of Engineering & Technology, Nandyal, Kurnool, Andhra Pradesh 518 501, India 2 Department of Mechanical Engineering, J.N.T.U.H College of Engineering, J.N.T. University, Hyderabad, Andhra Pradesh 500 085, India 3 e School of Engineering & Technology, Sri Padmavathi Mahila Visvavidyalayam, Women’s University, Tirupati, Chittoor, Andhra Pradesh 517 502, India Correspondence should be addressed to B. Sidda Reddy; bsrrgmcet@gmail.com Received 29 May 2013; Revised 7 October 2013; Accepted 11 October 2013 Academic Editor: Serge Abrate Copyright © 2013 B. Sidda Reddy et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. e prime aim of the present study is to present analytical formulations and solutions for the buckling analysis of simply supported functionally graded plates (FGPs) using higher order shear deformation theory (HSDT) without enforcing zero transverse shear stresses on the top and bottom surfaces of the plate. It does not require shear correction factors and transverse shear stresses vary parabolically across the thickness. Material properties of the plate are assumed to vary in the thickness direction according to a power law distribution in terms of the volume fractions of the constituents. e equations of motion and boundary conditions are derived using the principle of virtual work. Solutions are obtained for FGPs in closed-form using Navier’s technique. Comparison studies are performed to verify the validity of the present results from which it can be concluded that the proposed theory is accurate and efficient in predicting the buckling behavior of functionally graded plates. e effect of side-to-thickness ratio, aspect ratio, modulus ratio, the volume fraction exponent, and the loading conditions on the critical buckling load of FGPs is also investigated and discussed. 1. Introduction Functionally graded materials (FGMs) are the new gener- ation of novel composite materials in the family of engi- neering composites, whose properties are varied smoothly in the spatial direction microscopically to improve the overall structural performance. ese materials offer great promise in high temperature environments, for example, wear-resistant linings for handling large heavy abrasive ore particles, rocket heat shields, heat exchanger tubes, thermo- electric generators, heat engine components, plasma facings for fusion reactors, and electrically insulating metal/ceramic joints and also these are widely used in many structural applications such as mechanics, civil engineering, optical, electronic, chemical, mechanical, biomedical, energy sources, nuclear, automotive fields, and ship building industries to minimize thermomechanical mismatch in metal-ceramic bonding. Most structures, irrespective of their use, will be subjected to dynamic loads during their operational life. Increased use of FGMs in various structural applications necessitates the development of accurate theoretical models to predict their response. In the past, a variety of plate theories have been proposed to study the buckling behavior of FGM plates. e classical plate theory (CPT) provides acceptable results only for the analysis of thin plates and neglects the transverse shear effects. Javaheri and Eslami [1], Abrate [2], Mohammadi et al. [3], Mahdavian [4], Feldman and Aboudi [5], Shariat et al. [6], and Tung and Duc [7] employed this theory to analyze buckling behavior of FG plates. However, for moderately thick plates CPT underpredicts deflections and overpredicts buckling loads and natural frequencies. e first-order shear deformation theories (FSDTs) are based on Reissner [8] and Mindlin [9] accounts for the transverse shear deformation effect by means of a linear variation of inplane displacements and stresses through the thickness of the plate,