Finite element modeling and simulation of a two-transducer through-wall ultrasonic communication system

A finite element simulation of a through-wall ultrasonic communication system which permits data to be transferred from the inside of a sealed metal vessel to the outside without the need for physical penetrations is introduced. Two transducers are aligned axially on either side of a thick solid stainless steel wall. The outside transducer is forced with a continuous sinusoidal voltage at the crystal's nominal 1 MHz longitudinal resonant frequency, launching a wave into the wall. The transmitted beam is partially reflected off of the inside of the wall where the inside transducer is located. The amplitude of the reflected wave is modulated by switching the electrical impedance placed across the leads of the inside transducer. The reflected wave is received at the outside transducer and the continuous wave amplitude is sensed to detect the transmitted data bits. The system is modeled and simulated using a commercial finite element modeling package. A coupled stress-strain and piezoelectric analysis is performed using an axisymmetric geometry. The model represents an existing system from which physical measurements were taken. Excellent correlation between the model and system were observed and the model has been used to further optimize the communication system.