Modelling a piezoelectric actuator

Objectives from modelling a piezoelectric actuator

Piezoelectric devices are part of many appliances at home and in industry. As probes for medical imaging, pressure and flow sensors, or harvesting energy systems. As actuators for inkjet printers, nebulisers used for desinfection or micromotors in automotive and electronics. Their main advantage is robustness and low energy consumption.

Optimising the configuration of piezoelectric ceramics that will make the device vibrate is a way to reduce its development and operational costs. These ceramics are a good definition of multiphysics phenomena. When subject to an electric potential at their electrodes, they will deform and vibrate at a certain frequency. The model helps to find the frequency of the operational mode that will have the best energy conversion.

Results from simulation and information extracted

One carries the simulation in two steps:

Modal Eigenfrequency analysis of the piezoelectric actuator

This analysis can be fast to run and it uses less  RAM memory during simulation (unless the frequency spectrum is very large). It provides information about EMCC (Electromechanical Coupling Coefficient) of the device and thus the efficiency of the different Eigenmodes.

Depending on the deformation mode that one wants to actuate the device (bending, shear), it helps to select a few frequencies that are worth investigating further.

Frequency analysis of the actuator

Following the modal analysis, one can run a frequency harmonic analysis to better understand the mechanical behaviour of the device for each pre-selected frequency. It will give information about the stresses and displacements of the structure.

A calculation of the impedance over the frequency spectrum will also confirm or not the frequencies that are selected in the first step.