ACTIVE VIBRATION CONTROL OF PIEZO-LAMINATED CIRCULAR PLATE

Abstract

This work deals with the experimental study of vibration suppression of circular annular plate clamped at the inner boundary and free at the outer boundary using pie2oelectric patches. Piezoelectric material is used, both as a sensor and actuator. Proportional feed back control system-is used in this experiment. In the proportional feed back control method, the feed back voltage is generated as a function of position like quantity (i.e. strain). As the plate deforms, due to external excitation, the PZT film (sensor) attached to it also deforms and due to its characteristics, it develop a voltage proportional to the applied force. The voltage is amplified by the control system, to obtain the feedback voltage. This feedback voltage is applied to the actuator which develops counteractive deformation of the plate. This action is used to suppress the vibration of the plate. First of all, a brief description about objective of active vibration control methods are discussed which mainly focus on the reduction of vibration is done by automatic modification of the system structural response. Active vibration control is widely used because of its broad frequency response range, low additional mass, high adaptability and good efficiency. Subsequently, theoretical background of smart structures and smart materials are discussed in details which contents shape memory alloy, electrostrictive materials, magnetostrictive materials, fiber optics and piezoelectric materials. In which piezoelectric materials are discussed in details. Further a brief review of the available literatures on active vibration control of beams and circular plates are presented. In which optimum location of PZT patches are also discussed. After that, basic equations and formulations are presented in detail, which contents classical plate theory, modeling of circular plate with piezoelectric patches, constitutive equations of piezoelectric materials, governing equation of motion and sensor voltage relations. First the optimal locations of the sensor/actuator pairs are investigated by ANSYS simulation, because sensor/actuator pairs have a critical influence on the vibration suppression of smart structures. Hence, sensor/actuator pairs must be placed in high strain v regions and away from areas of low strains. An experimental set-up is developed which consist of circular annular plate, PZT patches, DAQ, signal conditioner and computer system with LabVIEW software. The plate is clamped at the inner boundary and excited by impulsive force at the outer boundary. The sensor readings are recorded in the computer with the help of data acquisition card and the vibration of the structure is controlled by the Piezo-actuation system by increasing the gain further logarithmic rate of decay are calculated for comparison purpose. Natural frequency with different aspect ratio are theoretically calculated and compared with the available literature. Mode shape with PZT patch and without PZT patches both are presented. Finally, experimental and numerical simulation shows that a combination of sensor-actuator-controller can be used to suppress the vibration in the plate. vi