58 Int. J. Automation and Control, Vol. 8, No. 1, 2014 Copyright © 2014 Inderscience Enterprises Ltd. Active vibration control of a thick piezolaminated beam with imperfectly integrated sensor and actuator layers Seyyed M. Hasheminejad* and Mohammad Vahedi Acoustics Research Laboratory, Center of Excellence in Experimental Solid Mechanics and Dynamics, School of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114 Iran Fax: 9821-77240488 E-mail: hashemi@iust.ac.ir E-mail: vahedi@iau.ac.ir *Corresponding author Abstract: A spatial state-space formulation based on the linear two-dimensional piezoelasticity theory and involving local/global transfer matrices is applied to investigate the active vibration suppression of a simply supported, arbitrarily thick, orthotropic elastic beam, imperfectly integrated with spatially distributed piezoelectric actuator and sensor layers on its top and bottom surfaces, respectively. A linear spring-layer model is adopted to simulate the bonding imperfections between the host structure and the piezoelectric layers. To assist control system design, system identification is conducted by applying a frequency domain subspace approximation method with N4SID algorithm. The state space model is constructed from system identification and used for state estimation and development of control algorithm. A linear quadratic Gaussian (LQG) controller is subsequently designed and simulated based on the identified model in order to actively control the response of the smart structure. The accuracy of analysis is established with the aid of a commercial finite element package. Keywords: piezocomposite beam; interfacial imperfection; exact solution; system identification; disturbance attenuation; optimal control; Kalman observer. Reference to this paper should be made as follows: Hasheminejad, S.M. and Vahedi, M. (2014) ‘Active vibration control of a thick piezolaminated beam with imperfectly integrated sensor and actuator layers’, Int. J. Automation and Control, Vol. 8, No. 1, pp.58–87. Biographical notes: Seyyed M. Hasheminejad received his BS degree from California State University, Chico, in 1983, his MS degree from Santa Clara University, Santa Clara, CA, in 1985, and his PhD in Mechanical Engineering from the University of Colorado, Boulder, in 1992. Since 1993, he has been a full time faculty member at the Mechanical Engineering Department, Iran University of Science and Technology. He has conducted various national and industrial research projects, publishing over 130 indexed research papers, being an active reviewer for various journals and evaluating boards, and a member of several technical committees in academic and professional societies.