Piezoelectric-mechanical-acoustic couplings from a PZT-actuated vibrating beam and its sound radiation

This paper presents a finite element modelling of flexural actuation of an aluminium cantilever beam by two thin plates made of piezoelectric PZT-ceramic material. An analytical study describes the actuators as flexural wave-source into the beam that once excited radiates sound waves into the surrounding air. FEM-calculations of piezoelectric-mechanical-acoustic aspects correlated together are then conducted with ANSYS that has been chosen for its coupled-field modelling capabilities. As the PZT-plates are polarised in their thickness direction but operate in the plane dimension, their input material properties are orthotropic and characterised by the three, stiffness, dielectric and piezoelectric, matrices. The finite element analysis takes into account a physical adhesive bonding between actuators and beam, as well as beam damping conditions. Sound radiation of the vibrating beam is calculated within an air sphere surrounding the beam and in contact with it by a fluid-structure interaction zone. Results are given in the form of spatial distributions of sound pressure and frequency response functions. A complete calculation example is also given for the sixth flexural vibration eigenmode at 1550 Hz of the beam. Validation of the numerical results is conducted through measurements for both piezoelectric-mechanical and mechanical-acoustic couplings. (C) 2003 Elsevier Ltd. All rights reserved.