The vibration sensor of metal core piezoelectric fiber

Abstract

The metal core piezoelectric fiber (MPF) is one of the new typical sensors and actuators. The metal core is precisely located at the center of the fiber and surrounded by the ceramic. The metal core can be used as an electrode and the other electrode is coated on the outer surface of the fiber. When an external voltage is applied between the electrodes, the electric field is assumed to be in the radial direction of the fiber. Hence the direction of the polarization in the polarized ceramic is radial. Because two electric electrodes are available in each fiber, a single fiber can be used as a sensor or an actuator. When MPF is mounted on the surface of a cantilever beam, an axial strain will be generated on the fiber as a dynamic load is applied at the tip of the beam. And a dynamic electric charge will be generated on the electrodes of MPF because of the piezoelectric effect. Based on the piezoelectric constitutive equations, the mechanical model of the sensor is established. When the tip of cantilever beam subjected to a dynamic lateral force, the analytical expressions of the electric charges generated on the electrodes of MPF have been derived from the constitutive equations. The electric charges of the MPF with platinum core or wolfram core, and different metal core to fiber radius ratios were calculated, when the tip of cantilever beam subjected to a dynamic lateral force. The effects of the radius ratio on the electric charge of the MPF sensor are investigated based on the numerical results of these equations. The dynamic vibration sensing properties of MPF sensor were experimentally studied. The first mode natural frequencies of cantilever beam is obtained using MPF sensor. The results show that the sensor can give a high sensitivity for the vibration of cantilever beam.