Microstructure Characterizations in Composite Media Using Ultrasonic Tomography
Date
Authors
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Research Projects
Organizational Units
Journal Issue
Is Version Of
Versions
Series
Begun in 1973, the Review of Progress in Quantitative Nondestructive Evaluation (QNDE) is the premier international NDE meeting designed to provide an interface between research and early engineering through the presentation of current ideas and results focused on facilitating a rapid transfer to engineering development.
This site provides free, public access to papers presented at the annual QNDE conference between 1983 and 1999, and abstracts for papers presented at the conference since 2001.
Department
Abstract
While tomographic techniques for radiographic image reconstruction are well established, the development of similar methods for ultrasonic data lags far behind. One of the principal reasons for this difference, despite the general similarity of the problems, is the fact that x-rays travel in a straight path even in nonhomogeneous medium and acoustic waves will generally follow a curved ray path. This introduces an additional uncertainty (ray path) into the image reconstruction algorithm. A further complication for acoustic waves is anisotropy. In most conventional image reconstruction algorithms, it is assumed that each ray traversing a given pixel will interact with the material in exactly the same way. In anisotropic media, due to the directional dependence of material properties, this is no longer the case. In this work, we explore possible techniques for overcoming these limitations. In particular, a variational formulation, based on Fermat’s principle, is used to correct for ray bending effects. Further, with the aid of some simplifying assumptions, corrections for directional property variations due to anisotropy can be introduced into the reconstruction algorithm.