Lead Research Organisation: Imperial College London
Department Name: Mechanical Engineering


Non-Destructive Evaluation (NDE) employs sensor and imaging technology to assess the condition of components, plant and engineering structures of all kinds during manufacture and in-service. The UK Research Centre in NDE (RCNDE) is a collaboration between 6 universities led by Imperial College and 16 large full member companies who are end users of the technology, with over 30 associate members largely drawn from the technology supply chain. The centre undertakes adventurous research in this technology area which is key to the safe and sustainable future of a broad cross-section of UK industry including high value manufacturing, aerospace, power generation, defence and oil & gas. The centre has now successfully established the UK as a world leader in multi-disciplinary Non-Destructive Evaluation (NDE) research and delivered a wide range of new technology, expertise and people into an area that had been fragmented for some decades.

RCNDE has attracted over £7.5M of industry cash and generated a pipeline of more than 50 exploitable NDE outputs at different stages of development. This has already delivered impact through improved technology for today's advanced manufacturing and plant operation requirements. The industrial members have now developed a cross-sector vision for the radical new approaches to NDE that will be needed to provide the inspection and qualification capabilities to meet their future business ambitions over the next 20 years and beyond. This proposal is therefore aimed at meeting these new long term research challenges, building on the successful track record of the centre to date. The Centre will include a wide portfolio of activities from feasibility studies and longer term, higher risk adventurous research, through medium term application research and development to short term practical projects and technology transfer activities with end-users and the supply chain.

The EPSRC funds that are the main subject of this proposal will support longer term, adventurous research in 4 key priority themes: (i) Enhanced imaging - focussed around improving reliability, automation and extracting maximum information from inspection data; (ii) Accurate characterisation - to make optimum use of the inspection data obtained from the imaging technology to quantify component condition; (iii) New techniques for new challenges - developing new modalities, techniques and sensor technologies for high value gaps in the capabilities needed for long term industry requirements and (iv) Permanent monitoring technology to provide a step improvement in the reliability of NDE.

55% of the cost of the centre over the 6 year programme will be met by industry and university contributions and 45% is requested from EPSRC. Industry funding will be used to partially support the first 4 years and fully fund the final two years of research; it will also fund feasibility studies, technology transfer and public engagement activities together with all of the centre running costs. The feasibility studies, horizon scanning workshops and outputs from the initial 4 year research programme will inform the choice of topics for the industry funded research in the final 2 years.

The implications of research success will be profound in terms of enabling the use of new engineering designs, optimising high value manufacturing processes, improving operational efficiencies and reducing production and running costs which will all contribute to UK competitive advantage.

Planned Impact

NDE is an important and growing sector, engaging product suppliers and service companies which deliver high impact in terms of safety, asset value maximization and competitive benefit to client industries. NDE is thus an essential enabling technology for end-users across a wide range of sectors, and NDE research is needed to facilitate new engineering designs and materials for both high value manufacturing, as well as for asset management and life extension of existing infrastructure.

Immediate impact will be with the industrial end-user partners of RCNDE directly involved with the research. These include the majority of the UK power, oil & gas, nuclear, defence, aerospace and transportation industries. They will benefit directly through more efficient and safer operation, fewer interruptions to production, reduced wastage, less outage time, and the ability to support new engineering developments. The wider end-user community will be able to access these benefits through the dissemination and technology transfer activities of the centre.

At a national level, improved NDE capability not only underpins key growth areas such as high value manufacturing and energy, but is also crucial to public safety. Ultimately the whole UK economy will benefit through greater efficiency and less down-time, and UK society through increased safety and reduced environmental risk.

Many of the beneficiaries are existing collaborators. 16 major end-user members of RCNDE are represented by NDEvR, the Industrial Partner in a Strategic Partnership with EPSRC. Through NDEvR, RCNDE now has 30 Associate members from the supply chain (many of them SMEs) to stimulate technology transfer. NDEvR has developed a long term vision for research needs across a range of market sectors and the proposed research will be directed at these priorities. Impact will be maximised by focused communication and engagement activities between academic partners and industry.
The research will involve a significant cadre of postdoctoral and student engineers which will contribute to recruitment of high achieving engineers into both the academic and industrial NDE communities, thereby introducing new engineering skills and capability as well as helping to rejuvenate an ageing demographic in this important area of engineering.

The dissemination of research will include a structured range of events involving academic and industrial partners and designed to foster collaboration. These will include 3 plenary meetings annually, a dedicated annual research conference, typically 3 technology readiness workshops and technology seminars each year, university visits by industrialists and industrial visits by academics. All of these strengthen communications, focus engagement and cement long-term relationships. Additional dissemination to the wider community will include journal publications, conference presentations, plenary lectures etc and we will build on emerging links with the TSB Catapult centres and the EPSRC manufacturing research centres.

We are also committed to public engagement, and will use the dedicated and nationally leading Centre for Public Engagement operated by the University of Bristol to drive this aspect forward. This will include involvement with outreach programmes to raise the profile of engineering in schools and promote the public understanding of NDE, for example through exhibits at science festivals, secondment and publications in the wider media. Academic and industrial members of the Centre will support wider initiatives to build engineering skills, academic leadership and safeguard long-term research through engagement with the relevant policy committees of professional institutions and national initiatives.


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Algehyne E (2015) A finite element approach to modelling fractal ultrasonic transducers in IMA Journal of Applied Mathematics

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Bai L (2015) Characterization of defects using ultrasonic arrays: a dynamic classifier approach in IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

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Bai L (2015) Ultrasonic characterization of crack-like defects using scattering matrix similarity metrics. in IEEE transactions on ultrasonics, ferroelectrics, and frequency control

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Cawley P (2021) A Development Strategy for Structural Health Monitoring Applications in Journal of Nondestructive Evaluation, Diagnostics and Prognostics of Engineering Systems

Description The UK Research Centre in Non-destructive Evaluation (RCNDE) is a collaboration between EPSRC, universities and industry to perform world-class research in NDE and related fields. The EPSRC funded 'core' research is divided into 4 Themes - outcomes from completed and near-completed projects are summarised here together with key references.


(a) Incomplete array imaging (Imperial College)
Development of algorithms which will reduce the number of projections required for accurate image reconstruction for both X-ray CT and ultrasonics while still enabling images of sufficient quality to be produced. Outputs include:
• Development of a fast hybrid Inverse-Fourier algorithm for limited-view CT, which maximises the advantages of both inverse and Fourier based imaging methods.
• A regularisation scheme based on an existing binarisation technique.
• A study comparing the new algorithm with existing techniques, which showed better imaging results and significant speed improvements compared to other iterative algorithms.

Key references:
• Jones GA, Huthwaite P, NDT & E International, Vol 93, pp 98-109, 2018

(b) Automatic methods for crack detection (University of Manchester)
The project aims to use automatic methods of image analysis developed in other fields to help identify cracks or abnormalities in manufactured components. The long term goal is increase the automation of imaging and interpretation, to improve reliability and reduce manpower.
• Understanding of machine learning techniques to identify abnormalities on images of components treated with dye penetrant.
• Improved methodology for modelling the normal appearance of components in a radiograph, enabling improved identification of abnormalities.
• Improved Random Forest based methods for detecting abnormalities in welds
• Novel Convolutional Neural Network approach for learning features useful for identifying abnormalities (which showed good performance when then combined with the Random Forest approach).
• Development of a procedure to automatically identify a particular location (weld region) for subsequent inspection;

Key references:
• Dong X, Taylor CJ, Cootes TF, Proc International Conference on Pattern Recognition, 2018.
• Dong X, Taylor CJ, Cootes TF, Proc 2nd International Workshop on Compact and Efficient Feature Representation and Learning in Computer Vision, 2018.

(c) Magnetic camera (University of Manchester)
Delivery of novel automation and objectivity to eddy current inspection (ET) and Magnetic Flux Leakage (MFL), by the development of a Magnetic Camera based on new Quantum Well Hall Effect (QWHE) sensors with enhanced sensitivity, frequency response and small physical size.
• QWHE sensor arrays were developed with sufficient sensitivity to detect small variations in induced transverse magnetic fields with increased lift-off distances.
• Prototype cameras were constructed and their capabilities demonstrated and quantified using applications provided by the industrial partners.
• A numerical simulation study of the interaction of AC magnetic fields with metallic objects, identifying the capabilities to measure crack length and depth.
• An experimental trial to compare the NDE performance of the QWHE sensors with current mainstream NDE techniques.

Key references:
• Liang, C-W., Balaban, E., Ahmad, E., Zhang, Z., Sexton, J., & Missous, M, Sensors and Actuators, A: Physical, Vol 265, pp 127-137, 2017
• Watson, J M., Liang, C-W., Sexton, J., Biruu, F., & Missous, M. 57th Annual British Conference on Non-Destructive Testing, Nottingham, United Kingdom, 2018.


(a) Characterisation of defects (Universities of Bristol, Strathclyde and Iowa State)
Using database search techniques to extract quantitative characterisation information from NDT data, focusing on ultrasonic data and later exploring generalisation to other modalities.
• The approach is to form a large database from simulations and then, for measured data, search this database to find the closest match.
• A new way of looking at this problem, termed parametric-manifold mapping, has been developed which involves constructing a surface in principal component space that represents all possible defects of a given type. The characterisation challenge then becomes one of finding the closest approach of measured data to this surface.
• The shape of this surface reveals fundamental insights into the nature of the defect characterisation information, telling us for example, which defects are easy/hard to characterise.
• Crucially the method also enables probability maps of defect characterisation to be plotted.

Key references:
• Velichko A, Bai L, Drinkwater BW, Proc. R. Soc. A Vol. 473, 2017.
• Bai L, Velichko A, Drinkwater BW, Journal of the Acoustical Society of America, Vol 143(1), pp 349-360, 2018.
• Safari, A., Zhang, J., Velichko, A., Drinkwater, BW, NDT & E International, Vol 94 pp 126-136, 2018.

(b) Characterisation of the internal structure of scattering solids (University of Strathclyde)
This research was aimed at determining the interior microstructure of safety critical components using ultrasonic phased array data (without prior knowledge of the microstructure) and then using this information to improve defect detection and imaging.
• A Bayesian approach was developed for the reconstruction of the spatial material map of a heterogeneous material using Full Matrix Capture (FMC) data from an Ultrasonic Array; the method was developed to use the full waveform contained in the FMC data set.
• A semi-analytical model was developed to describe the wave propagation through the Voronoi tessellation.
• The objective function is based on the cross-correlation distance between the semi-analytical model FMC output and the experimentally measured FMC data.
• Case studies concluded that the method was able to reconstruct the material map to such a degree that the resulting image quality for a defect was commensurate with the image that was produced when using the known material map.

Key references:

• Tant, K. M. M., Galetti, E., Mulholland, A. J., Curtis, A., & Gachagan, A. (2018). Inverse Problems, Vol 34(9), 2018

(c) Future transducer technologies (University of Strathclyde)
This project is exploring the use of emerging piezoelectric materials to achieve improved transduction performance and is also investigating more radical design concepts inspired by natural phenomena. Achievements include:
• An ultrasonic array device using a Cantor Set (CS) fractal geometry has been explored using both finite element (FE) modelling and experimentation and has shown improvements in both image resolution and signal strength compared to conventional arrays.
• A further advancement of the fractal geometry has been proposed which comprises orthogonal CS fractal geometries, known as the Cantor Tartan (CT). This is predicted to provide further improvements in array performance.
• A 32-element, 5MHz linear array, incorporating PMN-PT 1-3 piezo-polymer composite, has been designed and optimised using FE, with an operational bandwidth close to 90% achieved through a fabricated prototype device.
• A pipe organ-inspired backplate has been proposed for use in an air-coupled micro-machined transducer to increase operational bandwidth without loss of sensitivity has been designed, built and evaluated.

Key references:
• B. Zhu, B. P. Tiller, A. J. Walker, A. J. Mulholland and J. F. C. Windmill, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 65, no. 10, pp. 1873-1881, 2018.
• H. Fang, Z. Qiu, A. J. Mulholland, R. L. O'Leary and A. Gachagan, in IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 65, no. 12, pp. 2429-2439, . 2018.
• Algehyne, E. and Mulholland, A.J., IMA J. Appl. Maths, (2019) (accepted for publication).


(a) Multi-wave imaging for damage precursor detection (University of Bristol)
Development of new inspection approaches that exploit mixing between different wave modes (a pump and probe wave), specifically ultrasound with another wave e.g. ultrasound, thermal or magnetic. The programme has focused on nonlinear ultrasonics and provided significant advances in the field:
• Development of the nonlinear diffuse energy imaging technique which has enabled the detection and sizing of closed cracks with unprecedented accuracy while requiring the use of just a single ultrasonic array.
• A family of new nonlinear imaging techniques have been developed which utilises the more conventional coherent component of the field. While these techniques are not as sensitive as diffuse energy imaging, they are necessary for applications where a statistical diffuse state cannot be achieved.
• It has been shown how suppression of linear scattering features can be improved through compensation for instrumentation nonlinearity.
• Development of a nonlinear subharmonic array imaging technique, including an analysis of all possible mode pairs in application to fatigue crack imaging.

Key references:
• Potter JN, Croxford AJ, IEEE Transactions on ultrasonics, ferroelectrics and frequency control, Vol 65 (5) pp 870-880, 2018
• Cheng J, Potter JN, Croxford AJ, Drinkwater BW, Smart Mater. Struct., Vol 26 055006, 2017
• Cheng J, Potter JN, Drinkwater BW, Smart Mater. Struct., Vol. 27 065002, 2018

(b) Near infra-red techniques for NDE (University of Warwick)
Development of new approaches for inspection of materials and coatings using imaging and spectroscopy in the near-infrared and mid-infrared wavelength range. Outputs include:
• Demonstration of direct imaging in both the NIR and mid-IR wavelength bands as a function of source wavelength, together with demonstration of spectroscopy systems in both wavelength ranges.
• Imaging and monitoring of corrosion beneath paint layers
• Imaging the internal structure of non-metallic objects - e.g. honeycomb composites and thick glass fibre composite.
• Combination with ultrasound for the detection of corrosion under insulation (CUI)
• NIR spectroscopy for imaging of water ingress
• Tomographic imaging of polymer utility pipes

Key references:
• Laureti S, Sfarra S, Malekmohammadia H, Burrascano P, Hutchins DA, Senn L, Silipigni G, Maldague XPV, Ricci M, NDT & E International, Vol 98, pp 147-154, 2018.
• Silipigni G, Burrascano P, Hutchins DA, Laureti S, Petrucci R, Senni L, Torre L, Ricci M, NDT & E International Vol 87, pp 100-110, 2017.
• Senni L, Laureti S, Rizwan MK, Burrascano P, Hutchins DA, Davis LAJ, Ricci M, NDT & E International, Vol 102, pp 281-286, 2019.

(c) NDE for additive manufacturing (University of Nottingham)
This project has been focused on selective laser melting (SLM), an AM process technology that has been extensively developed in the last decade and now available commercially, and was also focused on an NDE method (Spatially Resolved Acoustic Spectroscopy - SRAS) which has particular advantages for this application.
• A demonstration SRAS setup was developed and integrated into an SLM build chamber to prove the feasibility of using the technique in an industrial context..
• Models were developed to quantify the spatial measurement capability, temporal inspection ability, and the associated costs of different measurement approaches.
• Research into piecewise rework of surface defects based on SRAS inspections.
• Measuring contaminants using SRAS scans.
• Influencing and measuring the microstructure of builds using seed crystals.
• Investigating other AM technologies where SRAS could be used to measure build parameters.

Key references:
• Hirsch M, Patel R, Li W, Guan G, Leach R K, Sharples S D, Clare A T, Additive Manufacturing Vol 13, pp 135-142, 2017.
• Patel R, Hirsch M, Dryburgh P, Pieris D, Achamfuo-Yeboah S, Smith R, Light R, Sharples S, Clare AT, Clark M, Appl. Sci. Vol 8(10), p 1991; 2018.
• Hirsch M, Dryburgh P, Catchpole-Smith S, Patel R, Parry L, Sharples S,. Ashcroft I, Clare AT, Additive Manufacturing. Additive Manufacturing, Vol 19, pp 127-133, 2018.


(a) Magnetic monitoring of corrosion in pipelines (University of Warwick & Imperial College)
An investigation into magnetic monitoring of pipelines for corrosion, initially studying the metal magnetic memory (MMM) method about which major claims have been made but on which there is very little peer reviewed literature and moving on to the magnetic tomography method (MTM). Significant progress has been made on understanding these methods and the indication is that they are very unlikely to be reliable in practice.
• Tests were performed on 23 steels, and also with and without remnant (bias) field, the presence of magnetite and during fatigue.
• Small but measureable effects are seen at low transducer lift-off; no change greater than the earth's magnetic field has been seen in any of the tests.
• No evidence has been found of cumulative signal growth under elastic or plastic cycling with any material tested unless the previous maximum load is exceeded.
• The effects with remnant (bias) field are exactly as would be expected with magnetic flux leakage.
• Tightly adhered magnetite oxide has a small effect and there was little change during fatigue cycling.
• At 1m from pipe range, a bolt 2m away can give the same perturbation as a typical corrosion defect through 50% of pipe wall, which probably explains the high false call rate in some trials.

Key references:
• Li Z, Jarvis R, Nagy PB, Dixon S, Cawley P, NDT & E International, Vol 92, pp 59-66, 2017.
• Li Z, Dixon S, Cawley P, Jarvis R, Nagy PB, Cabeza S, NDT & E International, Vol 92, pp 136-148, 2017.

(b) Ultrasonic monitoring of highly textured materials (Imperial College)
The aim was to develop a monitoring technique to compare successive measurements at the same location, so enabling the grain noise that makes standard ultrasonic inspection difficult to be subtracted out, leaving only signals due to damage growth.
• It has been shown that analytical models give a good approximation to the grain noise from large-grained materials seen with typical transducers at low frequencies.
• A methodology for the selection of transducers for permanently installed monitoring of large grained materials has been established.
• A methodology for establishing ROC (POD vs PFA) curves has now been tested thoroughly and used to establish the best processing method for guided wave monitoring data - this has been proved in a blind trial;

Key references:
• Liu, Y., Liu, C., Van Pamel, A. et al. J Nondestruct Eval, 36: 53, 2017.

(c) Data processing for NDE monitoring (Imperial College)
The aim of this project is to provide a road map for the complex monitoring systems of the future, with generic development of processing to compensate for system, environmental and operational variability so that high quality data can be provided to enable operator attention to be focussed on the areas where action is needed. Conclusions include:
• Permanently installed sensors provide real-time time domain data, allowing identification of trends.
• A blind trial on guided wave monitoring showed a 5x increase in sensitivity compared to one-off NDT - this opens the way to using lower frequencies with better volume coverage and lower noise in highly textured materials.
• Monitoring how the actual component responds to the actual operating conditions removes reliance on assumptions and therefore yields superior estimates.
• The uncertainty bands in remnant life estimates from rate-based monitoring in the example studied are about 8 times tighter than those obtained from periodic inspection.
• To take into account more complex scenarios such as varying loads, it is necessary to incorporate reliance on more assumptions.
• The work to date has looked at the Paris Law regime; further opportunities are expected earlier on in the fatigue life cycle.

Key references:
• Leung MSH, Corcoran J, Cawley, P, Todd, MD, International Journal of Fatigue, Vol 120, pp 162-174, 2019
• Liu C, Dobson J, Cawley P; Proc. Roy. Soc. A: Mathematical, Physical and Engineering Sciences Vol 473 (2199), 2017
• Heinlein, S, Cawley, P, Vogt, T and Burch, S; Materials Evaluation, Vol 76, pp1118-1126, 2018.
Exploitation Route The ultimate objective is for the research to lead to new and improved methods for inspection of plant and products by industry. As RCNDE is jointly funded by industrial end users, and also has more than 30 associate members from the supply chain, industry is well placed to take the research forward. We also expect follow-on development programmes to take research outputs to higher TRL levels. Exploitation routes used for previous RCNDE research include: • Open access - where universities make the results of research freely available and will often provide support to exploiting organisations • End user adoption - where end user members take up the technology for use in their own plant and facilities • Licensing - where commercial terms are agreed with one or more organisations to supply products or services to the market • Spin-out - where universities establish companies directly to supply products or services.
Sectors Aerospace, Defence and Marine,Chemicals,Construction,Energy,Manufacturing, including Industrial Biotechology,Transport

Description Industrial members of RCNDE have maintained close involvement with the research through workshops, provision of applications and samples. Industrial take-up has been promoted via targeted workshops and the findings are discussed at an annual conference of industrial collaborators - these have continued beyond the end of the grant and there was a (virtual) technology transfer workshop in Jan 2021. Follow-on activities are underway for all of the completed projects to raise the Technology Readiness Levels, some through further RCNDE research, some with funding from other agencies and some with industrial trials. Some of the work is also being taken forward with industrial partners via EngD and ICASE PhD programmes.
Title Comparison of Time Domain and Frequency-Wavenumber Domain Ultrasonic Array Imaging Algorithms for Non-Destructive Evaluation 
Description Supporting data for the paper entitled "Comparison of Time Domain and Frequency-Wavenumber Domain Ultrasonic Array Imaging Algorithms for Non-Destructive Evaluation" in Sensors, 2020. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
Title Data for: "Broadband 1-3 Piezoelectric Composite Transducer Design using Sierpinski Gasket Fractal Geometry" 
Description The simulated and experimental Matlab data sets (.mat) of: The transmit voltage response (TVR), correlated to Fig.8 and Fig.15; open circuit response (OCV), correlated to Fig.9 and Fig.16; Pulse Echo response,correlated to Fig.10 and Fig.18 and impedance response, correlated to Fig.14. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Title Exploring high-frequency eddy-current testing for sub-aperture defect characterisation using parametric-manifold mapping 
Description Data and supplementary material supporting the journal paper 'Exploring high-frequency eddy-current testing for sub-aperture defect characterisation using parametric-manifold mapping', by Hughes & Drinkwater in NDT&E International, 2021 
Type Of Material Database/Collection of data 
Year Produced 2021 
Provided To Others? Yes  
Organisation Airbus Group
Country France 
Sector Academic/University 
PI Contribution NDE research through RCNDE and related projects
Collaborator Contribution Funding through RCNDE membership and project sponsorship
Impact New and improved NDE capabilities
Start Year 2007
Description EDF-Energy 
Organisation EDF Energy
Country United Kingdom 
Sector Private 
PI Contribution NDE research through RCNDE and related projects
Collaborator Contribution Funding through RCNDE membership and project sponsorship; member of RCNDE Steering committee
Impact New and improved NDE capabilities
Start Year 2007
Description Iowa State University 
Organisation Iowa State University
Country United States 
Sector Academic/University 
PI Contribution Our research team at the University of Bristol are leading a project on Characterisation of defects using inverse models within the RCNDE research programme and are working a visiting researcher from Iowa State.
Collaborator Contribution Provision of a visiting researcher to the University of Bristol to work in the field of electromagnetic NDE within the RCNDE research programme on Characterisation of defects using inverse models.
Impact Early stage
Start Year 2014
Description Rolls-Royce plc 
Organisation Rolls Royce Group Plc
Country United Kingdom 
Sector Private 
PI Contribution NDE research through RCNDE and related projects
Collaborator Contribution Funding through RCNDE membership and project sponsorship; member of RCNDE Steering Committee
Impact Improved NDE capabilities
Start Year 2007
Description Science Exhibitions 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact The RCNDE research groups have undertaken a wide range of outreach activities and events relating to schools, professional societies and local organisations around the UK with funding from industrial partners and universities. Highlights include:

• RCNDE stand at the Royal Society Summer Science Exhibition 2017 (very competitive selection process)
• FUTURES event at the Bristol Science Museum 2018
• Construction of a portable Robotic NDE demonstration stand (University of Strathclyde) used at a wide range of events.
Year(s) Of Engagement Activity 2017,2018