On application of piezoelectric shear effect to active damping of transverse vibration in beams

In the paper the problem of active damping of transverse vibration of a beam by making use of piezoelectric elements with shear piezoelectric effect employed is taken up. The analysis was motivated by the fact that popular piezoelectric materials made of lead zirconate titanate ceramics (PZT) exhibit very strong shear effect, being roughly three times greater than the longitudinal effect. The shear effect can be applied to beam-like systems by gluing piezoelectric sensors and actuators not to external surfaces of a given structure but placing them e.g. between two parallel strips as it is realised in three-layer sandwich structures, in which the middle layer is to dissipate vibration energy. In the presented model the middle viscoelastic core is replaced with a purely elastic piezoelectric element. Some preliminary results obtained for the proposed model based on a cantilever Timoshenko's beam made of PZT are presented. The method of control, generalised with respect to the piezoelectric shear effect boundary conditions, and finally, the resonance characteristics corresponding to excitation by external harmonic force are discussed. Particularly advantageous effect of the active damping is confirmed for lower resonances, where the natural damping by internal friction in the material is weak.