Title

Modeling and optimization of non-phased two-dimensional ultrasonic arrays.

Date of Award

2002

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Physics

First Advisor

Maev, Roman Gr.,

Keywords

Physics, Acoustics.

Rights

CC BY-NC-ND 4.0

Abstract

Ultrasonic image acquisition with non-phased 2D arrays is a relatively new method in NDE inspection. Historically, ultrasonic array development progressed mostly in the medical imaging where phased arrays found a great application. However, in the field of NDE inspection of metals, heavy plastics and composites, and many other materials the applicability of phased arrays is often restricted due to physical limitations. On the other hand, using versatile systems with mechanical scanning is not always convenient. Therefore, non-phased arrays of independent elements have a strong potential for becoming a valuable tool for rapid ultrasonic image acquisition in the industrial environment as well as in many other areas where conventional methods may not be applicable. The main motivation of this work is to build the necessary mathematical apparatus for estimating the process of signal and image formation in such systems. A model of signal penetration through a complex multilayered structure with non-parallel interfaces is discussed in the plane-wave approximation. This model is then refined to finite-size transducers and finite-size defects inside the sample. A new method of obtaining the beam structure in such multi-layered media is presented. The advantage of this method is that it allows for a very fast calculation while the precision is still comparable to more precise and more computationally expensive methods. A new method of calculating the response of the transducer to defects inside the sample is presented and discussed. The results of numerical calculations using these two methods are discussed and compared with experimental data. Using these models, image formation algorithms together with new image refining techniques are discussed. Source: Dissertation Abstracts International, Volume: 65-07, Section: B, page: 3496. Adviser: Roman Gr. Maev. Thesis (Ph.D.)--University of Windsor (Canada), 2002.