Damping effect by contacting a piezoelectric element on an object in perpendicular direction of vibration

Abstract

This study demonstrates a novel method for vibration damping using a piezoelectric element. A piezoelectric transducer excited by ultrasonic vibrations is placed in contact with a vibrating object in a direction perpendicular to the vibration. In conventional methods, piezoelectric elements attached to vibrating objects are excited in the same direction as the vibration direction of the object. Such methods require complicated control and measurements for maintaining the vibration of the transducer in the phase opposite to the object’s vibration, to exert the damping effect. In contrast, the proposed method does not require adjustment of the transducer’s vibration phase according to the object because this method manipulates a friction loss between the transducer and a vibrating object for damping. This study confirmed a damping effect with the proposed method by conducting hammering tests on a cantilever. Furthermore, the parameters influencing the damping effect and the damping principle were considered. The damping ratio obtained from these tests was approximately 10 times the value when a non-excited transducer was statically pressed to the cantilever. Moreover, the test results suggested that the magnitude of the damping effect could be estimated by measuring the current flowing in the transducer, and that an optimal current to achieve the highest damping effect exists. The damping effect by the proposed method is considered to be triggered with a slip between the transducer and a vibrating object by suppressing the transverse oscillation of the transducer using the inertia effect caused by the transducer’s excitation. Furthermore, the increase of the impact force applied to the object by the excitation improves the damping effect. By measuring the stress waves in a long bar based on the one-dimensional elastic wave propagation theory, the impact force caused by the excited transducer was measured. The impact force had a peak at a specific current and changed with the same tendency as the damping ratio. The results suggested that both suppressing the transducer’s transverse oscillation and increasing the impact force cause the high damping effect by using the proposed method.

Keywords

• vibration damping
• piezoelectric transducer
• damping effect
• hammering test
• impact force