Title :
Ultrasonic characterization of stratified media with independent measurement of wave velocity and thickness
Author :
de Sousa, Ana V Greco ; Machado, João C. ; Pereira, Wagner C A
Author_Institution :
razilian Navy Inst. of Res., Rio de Janeiro, Brazil
Abstract :
Ultrasonic pulse-echo systems are well established tools for non-destructive evaluation, optimal measurement design and geoacoustic inversion techniques. Distance measurements must take into account the differences in wave velocities along the propagation path. This work presents an ultrasonic method to characterize the layers of a stratified medium, from independent measurements of wave velocity (c) and thickness (Z) of each layer. The model, based on Geometrical Acoustics, includes refraction. Two transducers are used: one active (3.4 MHz) and a hydrophone as a receptor, which is moved laterally through 15 positions. The distance between the transducers and the delay between the echoes, from, the interfaces separating the layers, received by them are used to calculate c and Z. A three-layered phantom containing acrylic (Z=9.1 mm), water (Z=13.1 mm) and PVC (Z=9.6 mm) was immersed in. a water tank and tested. The experimental results for the acrylic, water and PVC layers have a percentage rms error of 2.2, 4.2 and 6.7, for thickness,. and of 2.1, 4.0 and 6.2, for wave velocity, respectively.
Keywords :
acoustic wave velocity measurement; inhomogeneous media; thickness measurement; ultrasonic measurement; ultrasonic transducers; ultrasonic velocity measurement; 13.1 mm; 3.4 MHz; 9.1 mm; Geometrical Acoustics; distance measurements; hydrophone; propagation path; receptor; refraction; stratified media; thickness; transducers; ultrasonic characterization; ultrasonic pulse-echo systems; wave velocities; wave velocity; Acoustic measurements; Acoustic propagation; Acoustic transducers; Distance measurement; Geoacoustic inversion; Nonhomogeneous media; Pulse measurements; Thickness measurement; Ultrasonic variables measurement; Velocity measurement;
Conference_Titel :
Ultrasonics Symposium, 2002. Proceedings. 2002 IEEE
Print_ISBN :
0-7803-7582-3
DOI :
10.1109/ULTSYM.2002.1193531