Original Article Journal of Intelligent Material Systems and Structures 2016, Vol. 27(3) 295–313 Ó The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1045389X14566528 jim.sagepub.com Configuration optimization of piezoelectric patches attached to functionally graded shear-deformable cylindrical shells considering spillover effects Mojtaba Biglar and Hamid Reza Mirdamadi Abstract In this article, the optimal configurations of piezo-transducers for active vibration control of a functionally graded cylind- rical shell are analyzed. The first-order shear deformation theory is employed for kinematic formulation of functionally graded cylindrical shell and piezo-patches. The boundary conditions of functionally graded shear-deformable cylindrical shell are simply supported, and the piezo-patches are attached to its surface. The Rayleigh–Ritz technique is used for deriving dynamic formulation and discretizing functionally graded shear-deformable cylindrical shell as well as piezoelec- tric transducers. The major goal of this study is to find optimal locations and orientations of piezoelectric transducers. The optimization procedure is designed based on desired controllability and observability of contributing modes as well as undesirable modes. Furthermore, in order to limit spillover effect, the effects of residual modes are regarded. The optimization variables are positions and angular orientations of piezo-patches. Genetic algorithm is utilized to evaluate the optimal configurations. For active vibration control, a negative velocity feedback control algorithm is used. The numerical results show that the optimization procedure is effective for vibration reduction. Moreover, by locating trans- ducers in their optimal locations and orientations, the undesirable vibrations of functionally graded shear-deformable cylindrical shell would be suppressed quickly. Keywords optimal location, piezoelectric transducer, spillover effect, functionally graded shear-deformable cylindrical shell, first- order shear deformation theory, Rayleigh–Ritz modes, genetic algorithm Introduction In aerospace, marine, naval, architecture, chemical, automotive, mechanical, and civil engineering indus- tries, shell structures are the most functional whose vibration analysis is important. For example, thin func- tionally graded (FG) shear-deformable cylindrical shells are used as primary structures for submarines and air- craft, pipelines, and so on. Static and dynamic analyses of FG shear-deformable cylindrical shells have been studied (Alibeigloo, 2009; Alibeigloo and Nouri, 2010; Kumar et al., 2008; Saviz and Mohammadpourfard, 2010). Most of the studies used classical plate theory and first-order shear deformation theory (FSDT); how- ever, there are some novel theories for analyzing plates and shell (Alijani and Amabili, 2014; Amabili, 2014; Chen and Yu, 2010; Demasi and Yu, 2013; Yu and Hodges, 2004, 2005), which could give more accurate results. In some of these theories, it is not necessary to make any assumption, such as plane stress or plane strain. One of the most important challenges for engineer- ing structures is their vibration control that has received much more attention in recent years (Boscariol et al., 2011; Farshidianfar et al., 2012). There are several methods for suppressing structural vibrations, one of which is a collection of active control techniques. Piezoelectric materials, shape memory alloys, electro- strictive materials, electromagnetostrictive materials, electro- and magneto rheological fluids, and so on are a Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran Corresponding author: Hamid Reza Mirdamadi, Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran. Email: hrmirdamadi@cc.iut.ac.ir