Normal Incidence Ultrasonic Beam Transmission Through Steel Plates. Measuring and Modelling The Transmission Coefficient

Abstract

Ultrasonic beam transmission through solid plates has been extensively studied overthe past decades. Through this study many anomalies have been found, that plane-wave theory can not account for. It is therefore important to have a fundamentalunderstanding of these effects in order to accurately model GUW in solids. Throughthe use of experiments and modelling these effects can be studied.The objective of this thesis is to study ultrasonic beam transmission through steel ata normal incidence angle. This study is done by studying the on-axis pressure withmeasurement techniques used by numerous members of the acoustics group. Inaddition to the on-axis pressure the use of equidistant measurements along an axisare introduced to the normal incidence ultrasonic beam transmission measurement.This use of equidistant measurements allows for the use of 2D Fourier transforma-tions, and the study of beam transmission in the wavenumber domain. Using thesepressure wavenumber spectra the reconstruction of the transmission coefficient canbe achieved using results from measurements. This method is replicated in simula-tion by using the angular spectrum method and offers comparable results.