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| Unit name |
Ultrasonics and Acoustics |
| Unit code |
MENGM4500 |
| Credit points |
10 |
| Level of study |
M/7
|
| Teaching block(s) |
Teaching Block 1 (weeks 1 - 12)
|
| Unit director |
Professor. Drinkwater |
| Open unit status |
Not open |
| Pre-requisites |
None |
| Co-requisites |
None |
| School/department |
Department of Mechanical Engineering |
| Faculty |
Faculty of Engineering |
Description including Unit Aims
The material in this unit covers the underlying science of ultrasonic and acoustic wave propagation in elastic media, and the application of this science to non-destructive evaluation. Students will be introduced to the mathematical equations that govern the propagation of ultrasonic and acoustic waves. The course will use this as a foundation to develop the techniques used in modelling ultrasonic and acoustic wave propagation in practical situations. The theoretical material will be covered in a number of illustrated lectures, reinforced by worked example classes. In parallel with the theoretical aspect of the course, students will undertake a number of experimental and computer simulation tasks to demonstrate how the theory translates into practice. In general, these tasks will be drawn from examples from the field of non-destructive evaluation.
Aims:
To provide students with an understanding of the science of ultrasonic and acoustic wave propagation and the mathematic tools necessary to model such waves in non-destructive evaluation applications.
Intended Learning Outcomes
- Students will be given an overview of ultrasonics and acoustics and how these are exploited by a variety of non-destructive evaluation techniques.
- Students will understand the generic characteristics of waves, including the concept of a differential wave equation, the complex exponential method of describing a propagating wave and the meaning of terms such as wavenumber, frequency, wavelength and phase velocity.
- Students will learn the derivation of the basic equations describing ultrasonic waves in homogeneous, isotropic media and will be aware of the extension of this to more complex materials. The concept of shear and longitudinal wave modes as solutions to the wave equations in isotropic media will be introduced. The principle of superposition of solutions to the wave equation will be explained and the implications explored.
- Students will learn the conditions that must be satisfied when an ultrasonic wave is incident on a boundary between two different media and how this is embodied in the Snell-Descartes' law. The concepts of reflection coefficient, transmission coefficient and acoustic impedance will be introduced at this stage.
- Students will learn the simplifications that can be made in the case of plane wave propagation normal to the plane of multi-layered media and how such systems can be modelled using the transmission line formalism. This will be used to demonstrate the concepts of effective acoustic impedance and matching layers.
- Students will be introduced to various techniques for modelling sound fields, including ray tracing, Huygens' modelling and finite element methods. The relative merits and applicability of these techniques to different non-destructive evaluation situations will be considered.
- Students will be given an introduction to the various classes of guided ultrasonic waves, including Lamb, SH and Rayleigh waves. The students will be made aware of the benefits and practical difficulties associated with using guided waves for non-destructive evaluation, and the relevance of guided wave science to acoustic emission testing.
Teaching Information
We are proposing to experiment with two models of Fat unit for the 2009-10 academic year. In one mode the 10 credit unit will be taught in a single week. In the other mode the 10 credit unit will occupy two weeks; either mornings for week 1 and afternoons for week 2 or vice versa – afternoons for week 1 and mornings for week 2. Units running in parallel at the same time will be guaranteed not to be on the same programme. Furthermore, single week units on the same programme will not be scheduled in consecutive blocks with other single week units.
Lectures and structured computer modelling (Matlab) classes.
Assessment Information
Coursework based on; a) write-up of exercises and b) open ended assignment(s)
Reading and References
- Wave Motion in Elastic Solids, K. F. Graff, Oxford: Clarendon Press, 1975
- Ultrasonic Testing of Materials, 4th ed., J. Krautkramer and H. Krautkramer, Berlin: Springer-Verlag, 1987
- Acoustics of Layered Media I, L.M. Brekhovskikh and O. A. Godin, Berlin: Springer-Verlag, 1998.
- Ultrasonic Waves in Solid Media, J. L. Rose, Cambridge: Cambridge University Press, 2004.
