NONLINEAR VIBRATION OF FUNCTIONALLY GRADED PIEZOELECTRIC ACTUACTORS

Piezoelectric actuators have been extensively used in a variety of engineering applications such as microelectromechanical systems, active vibration control, acoustic and pressure sensing. This paper investigates the nonlinear free vibration of a novel class of monomorph and bimorph actuators made of functionally graded piezoelectric materials (FGPM) with piezo-elastic constants varying smoothly along the layer thickness according to a power law distribution in terms of the volume fraction of the constituents. The actuator is modeled as a Timoshenko beam to account for the effects of transverse shear deformation, axial and rotary inertia. The partial differential equations of motion which include the effect of local and global geometric imperfections due to fabrication process are derived by employing Hamilton's principle and von Karman type of nonlinear kinematics. The differential quadrature method is used to obtain the nonlinear vibration frequencies for FGPM monomorph and bimorph actuators. Numerical results are presented in tabular form showing the influences of material composition, slenderness ratio and initial geometric imperfection on both the linear and nonlinear frequency parameters.