Masters Theses

Date of Award

8-1982

Degree Type

Thesis

Degree Name

Master of Science

Major Professor

M. A. Breazeale

Committee Members

W. E. Deeds

Abstract

Evaluation of attenuation of ultrasonic waves in solids from pulse echo trains can be complicated by a number of factors. In this thesis one considers the effect of nonparallelism of the sample surfaces. A mathematical model for correcting the echo height for the effect of a wedge-shaped sample is constructed. By using a unique coordinate system, the path of a multiply-reflected ultrasonic wave is transformed into an equivalent unidirectional path. A diffraction correction then is applied by numerically integrating an improved version of the farfield solution to the diffraction integral. This model is used to interpret data taken on a steel plate which has different facets ground over a range of angles between 0 and 0.01175 radians. Plots are given of corrected attenuation measurements made with circular piezoelectric transucers having resonance frequencies between 3 and 7 MHz.

A comparison is made between the present model and that of Truell and Oates [J. Acoust. Soc. Am. 35,1382 (1963)], which was intended as an indicator of the necessity for applying a correction for nonparallelism. The present model corrects the first four echoes for _3 frequencies f < 6 MHz and angles γ < 4 x 10-3 radians.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS