Next-generation ultrasonic arrays (University of Bristol)
Research to develop array-based ultrasonic inspection techniques for difficult applications – including difficult defect morphologies, materials or inspection geometries. Outputs include:
- Development of generic modelling tools for simulating array data from arbitrarily shaped defects.
- Development of 3 new defect sizing strategies for different defect size regimes.
- Experimental demonstration of sizing and imaging techniques on real defects and components.
- Quantification of the effect of crack roughness on detectability, and optimisation of array imaging in materials with strong material back-scatter.
- Delivery of a freely available, comprehensive software platform to enable users to investigate and optimise imaging algorithms and facilitate technology transfer.
- Velichko, A., Wilcox, P., J. Acoust. Soc. Am., Vol. 128, pp.1004-1014, 2010.
- Zhang, J., Drinkwater, B., Wilcox, P., J. NDE, Vol. 29, pp. 222-232, 2010.
- Wilcox, P., Review Prog. QNDE, Vol. 30, pp. 890-897, 2011.
- Zhang, J., Drinkwater, B., Wilcox, P., IEEE Trans. Ultr. Ferroelect. Freq. Contr., V. 59, pp. 939-948, 2012.
- Zhang, J., Drinkwater, B., Wilcox, P., IEEE Trans. Ultr. Ferroelect. Freq. Contr., V. 60, pp.1732-1745, 2013.
Super resolution imaging in NDE (Imperial College)
Research based on new inverse scattering techniques applied to modern array technology, to improve current ultrasound NDE detection and characterisation techniques:
- Implementation of a near real-time single-frequency super-resolution algorithm.
- Understanding the limitations of using existing quantitative algorithms with standard linear arrays.
- Improved quantitative imaging algorithms to better deal with the limited view problem.
- Demonstration of the new imaging algorithms using simulations and experimental data.
- Experimental demonstration of broadband super resolution on notches in elastic solids.
- Simonetti, F., Fleming, M., Marengo, EA., J. Opt. Soc. Am A, 25: 292-303, 2008.
- Hutt, T. and Simonetti, F., J. Appl. Phys., Vol. 108, 064909, 2010.
- Huthwaite, P., and Simonetti, F., J. Acoust. Soc. Am., 103, 1722-34, 2011.
- Huthwaite, P., Zwiebel, A., Simonetti, F., IEEE Trans UFFC, 60, 603-613, 2012.
Laser ultrasonics for detection of damage precursors
(University of Nottingham)
Assessment and development of ‘nonlinear’ ultrasonic techniques for the early detection of damage precursors, prior to the formation of cracks and dislocations measurable by conventional linear ultrasonics. Outputs include:
- Development of a new system capable of repeatedly imaging highly accurate surface acoustic wave acoustoelastic measurements.
- Increased understanding of the relationship between acoustoelasticity (material nonlinearity), fatigue (damage precursor), and microstructure.
- A method for determining the porosity of fibre reinforced Ti-MMCs using massive linear velocity shift, understanding of the cause/mechanisms, and backed up by FEM.
- Ellwood, R., Stratoudaki, T., Sharples, S., Clark, M., and Somekh,M., 2014., J Acoust Soc Am (Accepted for publication 21 Jan 2014).
- Chen, X., Sharples, S.D., Clark, M., and Wright, D., J Acoust Soc Am Vol 133(2), 760-9, 2013.
- Stratoudaki, T., Ellwood, R., Sharples, S., Clark, M., Somekh, M.G., Collison, I.J., J Acoust Soc Am, Vol 129(4), 1721-1728, 2011.
- Ellwood R., Stratoudaki T., Sharples S.D., Clark M., and Somekh M.G., J Phys: Conf. Series. 278(1), 2011.
Advanced thermography (University of Bath)
Research programme aimed at identifying and investigating a range of novel approaches to enhance thermography techniques and to improve the basic understanding and physical basis of the method. Results have included:
- Development of an analytical equation that accurately represents the behaviour of 2D defects (or rotationally symmetric 3D defects) as an extension to the well‐known equation for 1D heat flow in a semi‐infinite sample with a Dirac delta heat input.
- Development and validation of a Finite Difference Equation (FDE) code based on the analytical equation which is now being used as the basis of software to provide advice to user on thermography technique set up and performance.
- Improved thermography techniques including long pulse thermography,
- Chatterjee, K., Tuli, S., Pickering, S. G. and Almond, D. P., NDT & E Int, 44 (7), pp. 655-667, 2011.
- Almond, D. P., Pickering, S. G., J App Phys, 111 (9), 2012.
- Pickering, S.G., Chatterjee, K., Almond, D.P. and Tuli, S., NDT & E Int, 58, pp. 72-77, 2013.
- D.P.Almond & S.G.Pickering., Materials Evaluation, 72, no.1, 83-90, 2014.
New approaches to NDE with micromachined transducers
(University of Warwick)
This project has successfully generated the basis for exploitation of the rapid and low cost Micro-Stereo Lithography (MSL) technique for future NDE transducer developments. Development and characterisation of a range of transducers has included:
- Electrostatic ultrasonic devices which have promise for structural health monitoring or acoustic emission monitoring.
- Electromagnetic Acoustic Transducer (EMAT) coils with different geometries to generate ultrasonic beams at various angles and to enable use as detectors for laser-generated ultrasound.
- Miniature and flexible eddy current arrays for inspection of components with difficult or varying geometries
- Ho, KS., Bradley, RJ., Billson, DR., and Hutchins, DA., Ultrasonics. 48, 1-5, 2008.
- Yin, X., Hutchins, DA., Diamond, GG., and Purnell, P., Cement and Concrete Res., Vol.40,1734-1743 2010.
- Dixon, SM., Burrows, SE., and Fan. Y., Ultrasonics, Vol 51, 7-16, 2011.
- Hutchins, DA., Billson, DR., Bradley, RJ., and Ho, KS., Ultrasonics Vol.51, 870-877, 2011.
- Cheneler, D., Bowen, J., Leigh, SJ., Purssell, CP., Billson,DR., Hutchins, DA., Ward, CL., Ultramicroscopy 1, 1214-1223, 2011.
Permanently installed monitoring of creep damage (Imperial College)
Development of a quasi-dc potential drop measurement technique for monitoring the progress of creep:
- Successful development of a method which effectively provides a high temperature strain gauge with a gauge factor of around 5-6 in the early stages of creep. In the later stages the gauge factor increases to around 10.
- Production of a robust measurement system that gives excellent results in the lab, is suitable for limited site trials and provides a potentially robust monitoring method.
- A deployable probe has been constructed and it has been confirmed that the changes due to voiding late in the creep life of a 2.25% Cr – 1% Mo ferritic steel specimen are less than 1%; this order of magnitude has been confirmed by an analytical model;
- The changes due to voiding may be larger in the vicinity of welds where the defects are concentrated in the plane of the fusion face; this is being investigated in a follow-on project.
- Sposito, G., Ward, C., Cawley, P., Nagy, P. and Scruby, C., NDT&E International, Vol 43, pp555-567, 2010.
- Madhi, E., Sposito, G., Davies, CM., Cawley, P. and Nagy, PB., Review of Progress in Quantitative NDE, Vol 30, DO Thompson and DE Chimenti (eds), American Institute of Physics, pp1631-1638, 2011.
- Prajapati, S., Nagy, P.B. and Cawley, P. NDT&E International, Vol 47, pp56-65, 2012.
- Prajapati, S., Nagy, P. B., and Cawley, P., Review of Progress in Quantitative NDE, Vol 31, DO Thompson and DE Chimenti (eds), American Institute of Physics, pp417-424, 2012.
Nonlinear material inspection (University of Bristol)
Programme to develop a robust nonlinear ultrasonic inspection technique, given that equipment often induces nonlinearity and the nonlinear signals are themselves typically several orders of magnitude smaller than the linear signals:
- The work has shown how harmonic generation methods need to be corrected to produce a measurement suitable for comparison across multiple specimens. In addition the effects of experimental variability were studied. This work is vital to ensure that measurements made at different distances and with different specimens can be compared.
- The research has shown the potential of the noncollinear technique, which relies on mixing of two waves to generate a third wave due to material nonlinearity and in principle can be used to detect changes in material state.
- Croxford, A., Wilcox, P., Drinkwater, B., Nagy, P., J. Acoust. Soc. Am., Vol. 126, pp. EL117-EL122, 2009.
- Liu, S., Croxford, A., Neild, S., IEEE Trans. Ultr. Ferroelectr. Freq. Contr., Vol. 58, pp. 1442-1451, 2011.
- Liu, S., Best, S., Neild, S., Croxford, A., NDT & E Int., Vol. 48, pp. 46-53, 2012.
- Best, S., Croxford, A., Neild, S., Ultrasonics, Vol. 54, pp. 442-450, 2014.
Reconfigurable systems for automated & remote NDE
(University of Strathclyde)
Research on novel robot traction and positioning, sensor integration and data fusion has successfully developed a number of small autonomous, wireless robotic devices with a range of inspection payloads geared for NDE applications involving restricted access or large areas. Outcomes include:
- Significant progress in characterising different positional sensors and algorithms for accurate robot positioning.
- Evaluation and enhancement of new sensors including air-coupled ultrasonic inspection, focusing on the creation of a synthetic ultrasonic array using a single robot with pulse-echo transducers, and a new ‘whisker’ sensor for surface characterisation
- Delivery of a demonstrator system (TRL 4) that can perform automated Magnetic Flux Leakage and visual inspection. Results from each dataset can be fused into a single composite result and presented clearly to the operator.
- Macleod CN, Pierce SG, Sullivan JC, Pipe A, Dobie G and Summan R., Accepted for publication in IEEE Sensors Journal, 2014.
- Dobie, G., Pierce, SG., and Hayward, G., NDT & E International, Volume 58, pp 10-17, September 2013.
- Dobie G., Summan, R., MacLeod, C., Pierce, SG., NDT&E International, Volume 57, pp 17-25, July, 2013.
- Jackson, JC., Summan, R., Dobie, G., Whiteley, S., Pierce, G., Hayward, G., IEEE Trans. Ultrason. Ferroelectr. Freq. Contr, Vol 60 (2), pp 343-355, 2013.
- Dobie, G., Summan, R., Pierce, SG., Galbraith, W., Hayward, G., IEEE Sensors Jour Vol 11 (10), pp 2458-2468, 2011.