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Unit information: Ultrasonic Non-Destructive Testing (Bristol University) in 2020/21

Unit name Ultrasonic Non-Destructive Testing (Bristol University)
Unit code MENGM0052
Credit points 10
Level of study M/7
Teaching block(s) Academic Year (weeks 1 - 52)
Unit director Professor. Wilcox
Open unit status Not open




School/department Department of Mechanical Engineering
Faculty Faculty of Engineering


Ultrasonic methods are among the most important tools 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 and inspection system design. The course is taught through a combination of 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 involing 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 (implicitly assessed in CW1 & CW2) their knowledge: of ultrasonic wave propagation phenomena and signal processing to analyse experimental ultrasonic signals to extract data relevant to NDT; simulate the ultrasonic field from both monolithic and array transducers, the latter under different focusing/steering conditions; simulate raw ultrasonic array data from an array applied to a simple system.
  • Combine (implicitly assessed in CW1 & CW2) and apply the principles taught to: develop protocols for automated experimental data analysis; develop different imaging algorithms for ultrasonic array data.
  • Evaluate: the performance of different imaging algorithms by defining and using metrics appropriate to the relevant NDT requirements (CW2)

Teaching details

The unit will be delivered through a combination of 10 x 1-hour lectures and 4 x 4-hour computer classes (all taught over one intensive teaching week). 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.

Assessment Details

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

  • Graff, K.F., Wave Motion in Elastic Solids. (1991), Dover Publications Inc. ISBN-10: 0486667456. ISBN-13: 9780486667454.
  • Krautkramer, J. & Krautkramer, H., Ultrasonic Testing of Materials. (1990), 4th ed., Springer-Verlag. ISBN-10: 0387512314. ISBN-13: 9780387512310.
  • Brekhovskikh, L.M. & Godin, O.A., Acoustics of Layered Media 1: Plane & Quasi-Plane Waves. (1998), 2nd ed., Springer. ISBN-10: 3540647244. ISBN-13: 9783540647249.
  • Rose, J.L., Ultrasonic Waves in Solid Media. (1999), Cambridge University Press. ISBN-10: 0521548896. ISBN-13: 9780521548892.