Vibration Damping Of Smart Structure Using Piezoelectric Elements

The piezoelectric materials as a new type of smart materials have many outstanding advantages, especially in vibration control, because of their excellent mechanical-electrical coupling characteristics. The vibration control method based on piezoelectric elements can be divided into three methods: passive, active and semi-active. In this paper, several new methods were proposed to overcome the drawbacks of classical vibration methods, and to improve the control performance of robustness.This paper analyzes in detail the enhancement of piezoelectric transducer by means of negative capacitive shunting. A negative capacitance in circuit can increase the electro-mechanical coupling coefficient of the system. In order to describe the characteristic behaviors of a piezoelectric damper connected with a negative capacitor branch circuit, the stiffness ratio and loss factor with respect to the non-dimensional frequency are considered, and the resistance and negative capacitance are chosen optimally according to the mechanical impedance of the system. The experimental analysis shows that the reasonable selection of the structure and parameters of the negative capacitor branch circuit can significantly reduce the multiple-mode vibration amplitudes over a wide frequency range.On the basis of the passive control system research with a negative capacitance, the paper also presents a novel SSD system with a negative capacitance circuit. The good control performance can be achieved by optimizing the value of negative capacitance. The new method overcomes the disadvantage that the control performance depends on the quality factor of inductance in the classical SSD method which is based on inductance. In this paper, the transfer function model of the system is presented based on mass spring damper; and the principle of synchronized switch damping with a negative capacitance circuit is discussed. The effectiveness of the new method are verified by experiments and simulations. The results show that the control performance using the new method is much better than using the classical one.A new method is proposed to separate the sensor signal from self-sensing actuator using a neural network besides of the two contents as stated above. In classical self-sensing actuator, a bridge circuit is used to separate the mixed signals. And the control performance mainly depends on the balance of bridge circuit. But it is very difficult to balance the bridge because of variation of the circumstance. In this paper, a vibration velocity estimation system using a neural network is developed. And an adaptive feedback controller was constructed using the Filtered-X LMS algorithm for the active vibration control. Experimental results show that the estimated vibration velocity of cantilever beam agrees well with the vibration velocity directly measured by a laser displacement sensor, the new system exhibits good damping performance in the vibration control of the cantilever composite beam.