Finite Element Modeling of Ultrasonic Transducers

Ultrasonic transducers are the most important part of an ultrasonic testing system which significantly affect the precision and accuracy of the measurements. Piezoelectric transducers are the most common ultrasonic transducers which include three major components: the piezoelectric disk, backing material, and matching layer. The optimal combination of these three components is traditionally done by trial and error. Analytical models used for this purpose have their own pros and cons and are not capable of predicting the complete performance of the transducer. Finite element modeling is an alternative method that can be used for designing ultrasonic transducers. This paper presents a finite element model for a 4 MHz ultrasonic transducer excited by a spike signal in pulse-echo mode. The model considers an ultrasonic transducer composed of a piezoelectric disk, a matching layer, and a backing material. The main advantage of this model in comparison to earlier models is the incorporation of piezoelectric elements instead of mimicking the piezoelectric effect by applying forces or displacements. In the developed model, the input is an electrical signal and the output is an electrical voltage. This makes this model very similar to the way a real ultrasonic transducer operates. The simulation results are compared with results obtained from experiments and very good agreement is observed.

Keywords:

Ultrasonic testing , Transducer , Finite element method , Piezoelectric