Numerical study of the geometric parameters effect on acoustic pressure of focal point of a linear phased array ultrasonic transducer

Phased array transducers because of their unique features¡ are used in many applications. Application of such transducers in non-destructive tests to detect defects such as porosity and crack¡ as well as stress measurement¡ in medicine for medical imaging and treatment of diseases¡ as well as in navigation range finder and acoustic (sonar)¡ are some of the applications of this system. One of the important features of this type of transducer to other transducers¡ is the ability to focus waves at any distance and angle. The main objective of this paper is to study geometric parameters of a linear phased array transducer with 8 piezoelectric elements such as width and thickness¡ the distance between elements as well as excitation frequency and voltage on acoustic pressure at the focal point using numerical methods. First¡ for the purpose of verification¡ the experimental result of an element was compared with the numerical approach. The experimental tests confirm the transducer’s behavior in terms of design¡ extracted algorithm and also the simulation. Acoustic pressure along the crystal axis was measured using both experimental and numerical methods. Experimental tests confirmed the accuracy of the transducer behavior in term of acoustic pressure. Operating frequency and mode shape of piezoelectric element disc shape with 53 mm diameter and thickness of 5 mm¡ was calculated using the finite element method. First radial mode in frequency of 45649 Hz was chosen as suitable frequency and shape mode. Algorithm to obtain the elements time delay to focus the waves was developed in the form of a computer program and its validity was investigated using the finite element method. As expected¡ due to the superposition of acoustic waves in the focal area over a period of time¡ its acoustic pressure is more than the time at which all crystals get excited simultaneously.