Byline: Ali Asghar Atai (1), Davood Lak (2) Keywords: Elasto-plastic analysis; FGPM; Hollow sphere; Pressure vessel; Electric response Abstract: In this work, the effect of electric potential on the mechanical (Stresses, strains, displacement) and electrical (electrical displacement and intensity) response of a Functionally graded piezoelectric (FGP) hollow sphere is analytically investigated. The sphere is under the action of internal/external pressure and temperature gradient as well. The inhomogeneity is based on power law in radial direction. The analysis is done in two parts: elastic response and plastic response, using Tresca yield criterion. It is shown by illustrative example that under internal pressure and assumed model parameters, the commencement of plastic region is from outside surface towards inside in the plastic zone is extended with the increase of electric potential. Interestingly, radial stress and displacement have an extreme not on the boundaries, but on the inside. Author Affiliation: (1) School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran (2) National Iranian Oil Co., Tehran, Iran Article History: Registration Date: 06/01/2015 Received Date: 19/12/2014 Accepted Date: 26/08/2015 Online Date: 13/01/2016 Article note: Ali Asghar Atai received his B.Sc. in mechanical engineering from the University of Tehran, Iran, in 1990. He obtained his M.Sc. and Ph.D. from the University of Alberta, Canada, in 1994 and 1998, respectively. He is currently an assistant professor in the school of Mechanical Engineering, college of Engineering, University of Tehran, Iran. His areas of research interest include flexible structural mechanics, continuous media, nano- and graded materials and optimization. Davood Lak received his B.Sc. degree from University of Kashan in Kashan, Iran, in 2004. He then received his M.Sc. degree from Islamic Azad University, Karaj Branch, Iran in 2013. He is currently a research engineer with NIOC (National Iranian Oil Company). His research interests are continuum mechanics, nanomechanics, composites and functionally graded materials (FGMs), finite elasticity and plasticity.