Damping Analyses of Structural Vibrations and Shunted Piezoelectric Transducers

Piezoelectric transducers in conjunction with appropriate electric networks can be used as a mechanical energy dissipation device. Alternatively, undesired mechanical energy of a structure could be converted into electrical energy that can be dissipated through a shunt network in the form of Joule heating. This paper presents an experimental method to calculate damping energy in mechanical systems. However, the mathematical description of damping mechanism is much more complicated, and any process responsible for the occurrence of damping is very intricate. Structural and piezoelectric damping are calculated and analysed in the case of pulse switching or SSDI semiactive vibration control technique. This technique which was developed in the field of piezoelectric damping consists in triggering the inverting switch on each extremum of the piezoelectric voltage which induces an increase of the electromechanical energy conversion. 1. Introduction Vibration damping is one of the manifestations of mechanical energy dissipation related to motion in mechanical systems. Damping processes have been studied for a long time. Damping forces are small compared to the other interactions in a mechanical system and yet their mathematical description remains much more complicated. Actually, any process responsible for the occurrence of damping is very intricate and the knowledge of it is insufficient. Sometimes just changing the system’s stiffness or mass to alter the resonance frequencies can reduce the unwanted vibration as long as the excitation frequencies do not change. But in most cases, the vibrations need to be dissipated using damping materials or devices that are tuneable with vibration. Several methods have been investigated in case of vibration damping. These methods have the forms of passive, semiactive, and active treatments which can be used for sound/vibration cancellation. Active control involves the use of active elements (actuators) along with sensors and controllers (analogue or digital) to produce an out-of-phase actuation to cancel the disturbance causing the noise/vibration [1]. All other methods that do not include a real-time active algorithm can be grouped under the passive control option. Passive damping refers to energy dissipation within the structure by add-on damping devices. Viscous dampers (dashpots), viscoelastic damping, tuned-mass dampers, dynamic absorbers, and shunted piezoelectric dampers are the mechanisms of passive vibration control. The most common types of passive damping treatments of viscoelastic materials were described by