1 Semi-analytical Modelling and Vibration Control of a Geometrically Nonlinear Plate Atta Oveisi *1 , Tamara Nestorović 1 , Ngoc Linh Nguyen 2 1* Ruhr-Universität Bochum, Mechanik adaptiver Systeme, Institut Computational Engineering, Bochum, Germany. E-Mail: atta.oveisi@rub.de 2 Computational Engineering, Vietnamese-German University, Ho Chi Minh City, Vietnam. This paper presents the dynamic modelling of a piezolaminated plate considering geometrical nonlinearities. The piezo-actuator and -sensor are connected via proportional derivative feedback control law. The Hamilton’s principle is used to extract the strong form of the equation of motion with the reflection of the higher order strain terms by means of the strain-displacement relationship of the von Karman type. Then the nonlinear partial differential equation (PDE) obtained is converted to a nonlinear algebraic equation by employing the combination of harmonic balance method and single-mode Galerkin’s technique. Finally, the vibration suppression performance and sensitivity of the dynamic response is evaluated for various control parameters and magnitudes of external disturbance. Keywords: Geometrical nonlinearity; piezolaminated plate; vibration control; harmonic balance. 1. Introduction Special requirements on modern mechanical structures such as the lightness and flexibility may result in vibration which then should be addressed by additional elements in order to guarantee the robustness of their response in the presence of undesired disturbance. The realization of such structures is obtained by employing multi-domain transducers. These structures also known as smart structures are active with respect to the environmental excitation and therefore can affect the dynamic response of the passive system 1,Error! Reference source not found. . The active vibration control in comparison to passive methods is proven to be more effective especially in cases where additional masses should be avoided, the system is highly nonlinear, or under time varying mechanical disturbance 3,4 . Piezoelectric materials are typical candidates for active devices due to their capability to couple the strain and electric fields and due to the easiness of binding with the host structure. Therefore, a large number of researches have been devoted to the dynamic modelling of such structures 5,6,Error! Reference source not found.,8,9,10,11,12,1314 . In this paper, the systematic formulation of the nonlinear dynamic equation of motion, as well as an appropriate semi-analytical solution for the active vibration control of a simply supported smart plate, is presented. 2. Mathematical modelling The sandwich piezolaminate plate, as shown in Fig. 1, consists of an elastic core, piezo-sensor layer, and piezo-actuator layer which are perfectly bounded on top and bottom of the core layer, respectively. Considering