Modeling of harmonic measurement radiated by a plane circular piston in fluids

Abstract

In recent years, the use of nonlinear ultrasound in medical and industrial applications has increased rapidly. Harmonic signals, generated from nonlinear distortion of ultrasonic wave propagation in fluid or solid media, play an important role not only in ultrasonic medical imaging to provide higher resolution and higher contrast to tissue ratio, but also in nondestructive testing of fatigue cracks to provide higher sensitivity. We present a finite element model that embodies all the factors (diffraction, attenuation, receiver integration and tone-burst excitation) mentioned previously to describe the nonlinear characteristics of the ultrasonic field radiated by a plane circular piston source in fluids more accurately. A computer controlled ultrasonic system (RAM-5000 SNAP, Ritec Inc.) was used to verify the numerical predictions. The fundamental and the second harmonic versus axial distance are compared, and a reasonable agreement is achieved.