In this paper an effort has been made to actively attenuate the vibration of a single link planar flexible manipulator with rotary joints using a combination of ferro-magnetic alloys/polyethylene-polyethylene glycol and terfenol-D as smart nano-composite. Such materials can be used as intelligent distributed layers over the link to introduce distributed control of vibration. The method utilizes the property that under a control voltage/magnetic flux, the smart materials bonded to the flexible structure deforms and generates a bending strain through end moments that opposes the structural deformation. Proportional damping scheme is used to model the damping of passive layers. Together with the active material this arrangement has shown high efficiency to reduce the vibration. However, to identify the elastic displacements as generalized coordinates estimation of states related to an optimal performance is required. This is carried out by discretization of the elastic motion through the assumed mode technique and applying Kalman filter for state estimation