Unit information: Ultrasonic Non-Destructive Testing in 2015/16

Unit name	Ultrasonic Non-Destructive Testing
Unit code	MENGM0019
Credit points	10
Level of study	M/7
Teaching block(s)	Teaching Block 1 (weeks 1 - 12)
Unit director	Professor. Wilcox
Open unit status	Not open
Pre-requisites	Computer-based modelling 1 and 2 (MENG11511, MENG21712) or equivalent programming experience, preferably including Matlab.
Co-requisites	None
School/department	School of Engineering Mathematics and Technology
Faculty	Faculty of Engineering

Description including Unit Aims

Ultrasonic methods are the most important tool for Non-Destructive Testing (NDT) of engineering components and structures. 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 NDT. The mathematical equations that govern the propagation of ultrasonic waves are introduced and used as a foundation to develop the techniques used in modelling ultrasonic wave propagation in practical situations. Signal processing techniques for analysing ultrasonic data to elicit structural information (e.g. thickness, speed of sound, attenuation) are also covered in the course. Assessment is via two pieces of coursework covering experimental data analysis, wavefield simulation and inspection system design. The course is taught through a combination of weekly illustrated lectures and computing classes to support the coursework.

Intended Learning Outcomes

On completion of the unit, the student should be able to:

• Recall (implicitly assessed in CW1 & CW2): why there is a need for NDT; the main methods of NDT and their basic principles; the general features of the wave equation; the general characteristics of waves and definitions of terms such as frequency, period, wavelength, wavenumber, dispersion, phase velocity & group velocity; that two ultrasonic wave modes (shear and longitudinal) exist in solids; that in bounded solids (e.g. plates) guided waves exist; that reflection and refraction take place at interfaces; the general principles of ultrasonic NDT using bulk and guided waves; that modelling ultrasonic phenomena is computationally challenging and that many approaches invoking different levels of approximation exist such as ray tracing, Huygens' modelling and finite element methods.
• Explain (implicitly assessed in CW1 & CW2): how the wave equation can be derived for 1D elastic waves; the concept of linear superposition and its application to waves; how a propagating wave can be described using complex exponential notation; why two wave modes are possible in elastic solids; what boundary conditions must be satisfied at interfaces between media; the concept of acoustic impedance and transmission/reflection coefficients for waves normally incident on a boundary; Snell’s law for obliquely incident waves on a boundary; the equivalence between time- and frequency-domain representations of waves; the basic principles of Huygens’ modelling; how an ultrasonic array can be used to image the interior of a component.
• Apply their knowledge: of ultrasonic wave propagation phenomena and signal processing to analyse experimental ultrasonic signals to extract data relevant to NDT (CW1); simulate the ultrasonic field from both monolithic and array transducers, the latter under different focusing/steering conditions (CW2); simulate raw ultrasonic array data from an array applied to a simple system (CW2).
• Combine and apply the principles taught to: develop protocols for automated experimental data analysis (CW1); develop different imaging algorithms for ultrasonic array data (CW2).

Evaluate: the performance of different imaging algorithms by defining and using metrics appropriate to the relevant NDT requirements (CW2)

Teaching Information

The unit will be delivered through a combination of 11 x 1-hour lectures (1 per teaching week in TB1) and 11 x 1-hour computer classes (1 per teaching week in TB1). All lecture notes, together with additional material is provided through Blackboard. The lectures will include demonstrations of state-of-the-art ultrasonic equipment, ranging from single-channel pulse-echo systems to array imaging systems. For the computer classes students will be provided with a structured set of exercises leading into the two assessed pieces of work. The first few computer classes will introduce the basics of ultrasonic simulation using Matlab and will include time for informal feedback to be given at the end of Week 4 on the students’ progress up to that point. CW1 will be submitted at the end of Week 6 and CW2 at the end of Week 12. Formative feedback from CW1 will be provided before the end of Week 9.

Assessment Information

Coursework as follows:

CW1. Analysis of experimental ultrasonic data indicating how, e.g., thickness, velocity and attenuation may be deduced in the time and frequency domains - report required (40%)

CW2. Design and modelling of an ultrasonic array to satisfy a given inspection specification - report required (60%)

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, 200