Imperial College London

ProfessorMichaelLowe

Faculty of EngineeringDepartment of Mechanical Engineering

Professor in Mechanical Engineering
 
 
 
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Contact

 

+44 (0)20 7594 7071m.lowe Website

 
 
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Assistant

 

Ms Nina Hancock +44 (0)20 7594 7068

 
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Location

 

566City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

285 results found

Choi W, Shi F, Lowe MJS, Skelton EA, Craster RV, Daniels WLet al., 2018, Rough surface reconstruction of real surfaces for numerical simulations of ultrasonic wave scattering, NDT and E International, Vol: 98, Pages: 27-36, ISSN: 0963-8695

© 2018 Elsevier Ltd The scattering of waves by rough surfaces plays a significant role in many fields of physical sciences including ultrasonics where failure surfaces are often rough and their accurate identification is critical. The prediction of the strength of scattering can be hampered when the roughness is not adequately characterised and this is a particular issue when the surface roughness is within an order of the incident wavelength. Here we develop a methodology to reconstruct, and accurately represent, rough surfaces using an AutoRegressive (AR) process that then allows for rapid numerical simulations of ultrasonic wave rough surface scattering in three dimensions. Gaussian, exponential and AR surfaces are reconstructed based on real surface data and the statistics of the surfaces are compared with each other. The statistics from the AR surfaces agree well with those from actual rough surfaces, taken from experimental samples, in terms of the heights as well as the gradients, which are the two main factors in accurately predicting the wave scattering intensities. Ultrasonic rough surface scattering is simulated numerically using the Kirchhoff approximation, and comparisons with Gaussian, exponential, AR and real sample surfaces are performed; scattering intensities found using AR surfaces show the best agreement with the real sample surfaces.

JOURNAL ARTICLE

Eckel S, Huthwaite P, Lowe M, Schumm A, Guérin Pet al., 2018, Establishment and validation of the Channelized Hotelling Model Observer for image assessment in industrial radiography, NDT and E International, Vol: 98, Pages: 1-7, ISSN: 0963-8695

© 2018 The Authors A new method for industrial radiography is presented to assess image quality objectively. The assessment is performed by a modelled observer developed to interpret radiographic images in order to rate the detectability of structural defects. For the purpose of qualifying radiographic NDE procedures, computational tools simulate the image, but should additionally automatically assess the associated image quality instead of relying on human interpretation. The Channelized Hotelling Model Observer (CHO) approach, originally developed for medical imaging, is here developed for industrial NDE applications to measure objectively the defect's detectability. A validation study based on a comparison of the model's efficiency of observing circular and elongated flaws shows that the CHO outperforms other detectability models used by industry. Furthermore, the model's reliability was verified by comparing it to psychophysical data.

JOURNAL ARTICLE

Phillips R, Duxbury D, Huthwaite P, Lowe Met al., 2018, Simulating the ultrasonic scattering from complex surface-breaking defects with a three-dimensional hybrid model, NDT and E International, Vol: 97, Pages: 32-41, ISSN: 0963-8695

© 2018 Elsevier Ltd Modelling is increasingly relied on for the design and qualification of ultrasonic inspections applied to safety-critical components. Numerical methods enable the simulation of the ultrasonic interaction with realistic defect morphologies; however, the computational requirements often limit their deployment. The hybrid simulation technique, which combines semi-analytical and numerical methods, realises the potential of high fidelity numerical modelling without the limiting computational factors. The inspection of thick section components for near-backwall surface-breaking defects results in large propagation distances, making them a key application of hybrid modelling. This work presents a methodology for efficiently simulating the ultrasonic inspection of complex surface-breaking defects using a hybrid model. The model is initially verified against full numerical simulation; further validation is presented by comparison to an experimental scan over an artificially machined surface-breaking notch. The potential of the new hybrid method is then demonstrated by carrying out a Monte Carlo analysis on the scattered field from surface-breaking defects with randomly rough surfaces and the results are compared to the Kirchhoff approximation.

JOURNAL ARTICLE

Phillips R, Duxbury D, Huthwaite P, Lowe Met al., 2018, Simulating the ultrasonic scattering from complex surface-breaking defects with a three-dimensional hybrid model, NDT & E INTERNATIONAL, Vol: 97, Pages: 32-41, ISSN: 0963-8695

JOURNAL ARTICLE

Shi F, Lowe MJS, Skelton EA, Craster RVet al., 2018, A time-domain finite element boundary integral approach for elastic wave scattering, COMPUTATIONAL MECHANICS, Vol: 61, Pages: 471-483, ISSN: 0178-7675

JOURNAL ARTICLE

Van Pamel A, Sha G, Lowe MJS, Rokhlin SIet al., 2018, Numerical and analytic modelling of elastodynamic scattering within polycrystalline materials., J Acoust Soc Am, Vol: 143

The elastodynamic behavior of polycrystalline cubic materials is studied through the fundamental propagation properties, the attenuation and wave speed, of a longitudinal wave. Predictions made by different analytical models are compared to both numerical and experimental results. The numerical model is based on a three-dimensional Finite Element (FE) simulation which provides a full-physics solution to the scattering problem. The three main analytical models include the Far-Field Approximation (FFA), the Self-Consistent Approximation (SCA) to the reference medium, and the herein derived Second Order Approximation (SOA). The classic Stanke and Kino model is also included, which by comparison to the SOA, reveals the importance of the distribution of length-scales described in terms of the two-point correlation function in determining scattering behavior. Further comparison with the FE model demonstrates that the FFA provides a simple but satisfactory approximation, whereas the SOA shows all-around excellent agreement. The experimental wave velocity data evaluated against the SOA and SC reveal a better agreement when the Voigt reference is used in second order models. The use of full-physics numerical simulations has enabled the study of wave behavior in these random media which will be important to inform the ongoing development of analytical models and the understanding of observations.

JOURNAL ARTICLE

Zhang C, Huthwaite P, Lowe M, 2018, The Application of the Factorization Method to the Subsurface Imaging of Surface-Breaking Cracks, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, Vol: 65, Pages: 497-512, ISSN: 0885-3010

JOURNAL ARTICLE

Egerton JS, Lowe MJS, Huthwaite P, Halai HVet al., 2017, Ultrasonic attenuation and phase velocity of high-density polyethylene pipe material, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, Vol: 141, Pages: 1535-1545, ISSN: 0001-4966

JOURNAL ARTICLE

Egerton JS, Lowe MJS, Huthwaite P, Halai HVet al., 2017, A multiband approach for accurate numerical simulation of frequency dependent ultrasonic wave propagation in the time domain, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, Vol: 142, Pages: 1270-1280, ISSN: 0001-4966

JOURNAL ARTICLE

Haith MI, Ewert U, Hohendorf S, Bellon C, Deresch A, Huthwaite P, Lowe MJS, Zscherpel Uet al., 2017, Radiographic modelling for NDE of subsea pipelines, NDT & E INTERNATIONAL, Vol: 86, Pages: 113-122, ISSN: 0963-8695

JOURNAL ARTICLE

Haith MI, Huthwaite P, Lowe MJS, 2017, Defect characterisation from limited view pipeline radiography, NDT & E INTERNATIONAL, Vol: 86, Pages: 186-198, ISSN: 0963-8695

JOURNAL ARTICLE

Quintanilla FH, Lowe MJS, Craster RV, 2017, The symmetry and coupling properties of solutions in general anisotropic multilayer waveguides, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, Vol: 141, Pages: 406-418, ISSN: 0001-4966

JOURNAL ARTICLE

Shi F, Lowe M, Craster R, 2017, Diffusely scattered and transmitted elastic waves by random rough solid-solid interfaces using an elastodynamic Kirchhoff approximation, PHYSICAL REVIEW B, Vol: 95, ISSN: 2469-9950

Elastic waves scattered by random rough interfaces separating two distinct media play an important role in modeling phonon scattering and impact upon thermal transport models, and are also integral to ultrasonic inspection. We introduce theoretical formulas for the diffuse field of elastic waves scattered by, and transmitted across, random rough solid-solid interfaces using the elastodynamic Kirchhoff approximation. The new formulas are validated by comparison with numerical Monte Carlo simulations, for a wide range of roughness (rms σ≤λ/3, correlation length λ0≥ wavelength λ), demonstrating a significant improvement over the widely used small-perturbation approach, which is valid only for surfaces with small rms values. Physical analysis using the theoretical formulas derived here demonstrates that increasing the rms value leads to a considerable change of the scattering patterns for each mode. The roughness has different effects on the reflection and the transmission, with a strong dependence on the material properties. In the special case of a perfect match of the wave speed of the two solid media, the transmission is the same as the case for a flat interface. We pay particular attention to scattering in the specular direction, often used as an observable quantity, in terms of the roughness parameters, showing a peak at an intermediate value of rms; this rms value coincides with that predicted by the Rayleigh parameter.

JOURNAL ARTICLE

Shi F, Lowe MJS, Craster RV, 2017, Recovery of correlation function of internal random rough surfaces from diffusely scattered elastic waves, JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, Vol: 99, Pages: 483-494, ISSN: 0022-5096

JOURNAL ARTICLE

Van Pamel A, Sha G, Rokhlin SI, Lowe MJSet al., 2017, Finite-element modelling of elastic wave propagation and scattering within heterogeneous media, PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 473, ISSN: 1364-5021

JOURNAL ARTICLE

Choi W, Skelton EA, Pettit J, Lowe MJS, Craster RVet al., 2016, A Generic Hybrid Model for the Simulation of Three-Dimensional Bulk Elastodynamics for Use in Nondestructive Evaluation, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, Vol: 63, Pages: 726-736, ISSN: 0885-3010

JOURNAL ARTICLE

Egerton JS, Lowe MJS, Halai HV, Huthwaite Pet al., 2016, Improved FE Simulation of Ultrasound in Plastics, 42nd Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE), Publisher: AMER INST PHYSICS, ISSN: 0094-243X

CONFERENCE PAPER

Haith MI, Ewert U, Hohendorf S, Bellon C, Deresch A, Huthwaite P, Lowe MJS, Zscherpel Uet al., 2016, Modelling Based Radiography for NDE of Subsea Pipelines, 42nd Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE), Publisher: AMER INST PHYSICS, ISSN: 0094-243X

CONFERENCE PAPER

Huthwaite P, Lowe M, Cawley P, 2016, Guided Wave Tomography Performance Analysis, 42nd Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE), Publisher: AMER INST PHYSICS, ISSN: 0094-243X

CONFERENCE PAPER

Leinov E, Lowe MJS, Cawley P, 2016, Ultrasonic isolation of buried pipes, JOURNAL OF SOUND AND VIBRATION, Vol: 363, Pages: 225-239, ISSN: 0022-460X

JOURNAL ARTICLE

Leinov E, Lowe MJS, Cawley P, 2016, Investigation of guided wave propagation in pipes fully and partially embedded in concrete, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, Vol: 140, Pages: 4528-4539, ISSN: 0001-4966

JOURNAL ARTICLE

Quintanilla FH, Lowe MJS, Craster RV, 2016, Full 3D dispersion curve solutions for guided waves in generally anisotropic media, JOURNAL OF SOUND AND VIBRATION, Vol: 363, Pages: 545-559, ISSN: 0022-460X

JOURNAL ARTICLE

Seher M, Huthwaite P, Lowe MJS, 2016, Experimental Studies of the Inspection of Areas With Restricted Access Using A0 Lamb Wave Tomography, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, Vol: 63, Pages: 1455-1467, ISSN: 0885-3010

JOURNAL ARTICLE

Shi F, Lowe MJS, Xi X, Craster RVet al., 2016, Diffuse scattered field of elastic waves from randomly rough surfaces using an analytical Kirchhoff theory, JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, Vol: 92, Pages: 260-277, ISSN: 0022-5096

JOURNAL ARTICLE

Van Pamel A, Huthwaite P, Brett CR, Lowe MJSet al., 2016, Numerical simulations of ultrasonic array imaging of highly scattering materials, NDT & E INTERNATIONAL, Vol: 81, Pages: 9-19, ISSN: 0963-8695

JOURNAL ARTICLE

Van Pamel A, Nagy PB, Lowe MJS, 2016, On the dimensionality of elastic wave scattering within heterogeneous media, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, Vol: 140, Pages: 4360-4366, ISSN: 0001-4966

JOURNAL ARTICLE

Ewert U, Tschaikner M, Hohendorf S, Bellon C, Haith MI, Huthwaite P, Lowe MJSet al., 2015, Corrosion Monitoring with Tangential Radiography and Limited View Computed Tomography, 42nd Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE), Publisher: American Institute of Physics (AIP), ISSN: 1551-7616

Accurate and reliable detection of subsea pipeline corrosion is required in order to verify the integrity of the pipeline. A laboratory trial was conducted with a representative pipe sample. The accurate measurement of the wall thickness and corrosion was performed with high energy X-rays and a digital detector array. A 7.5 MV betatron was used to penetrate a stepped pipe and a welded test pipe of 3 m length and 327 mm outer diameter, with different artificial corrosion areas in the 24 mm thick steel wall. The radiographs were taken with a 40 x 40 cm² digital detector array, which was not large enough to cover the complete pipe diameter after magnification. A C-arm based geometry was tested to evaluate the potential for automated inspection in field. The primary goal was the accurate measurement of wall thickness conforming to the standard. The same geometry was used to explore the ability of a C-arm based scanner in asymmetric mode for computed tomography (CT) measurement, taking projections covering only two thirds of the pipe diameter. The technique was optimized with the modelling software aRTist. A full volume of the pipe was reconstructed and the CT data set was used for reverse engineering, providing a CAD file for further aRTist simulations to explore the technique for subsea inspections.

CONFERENCE PAPER

Fan Z, Mark AF, Lowe MJS, Withers PJet al., 2015, Nonintrusive Estimation of Anisotropic Stiffness Maps of Heterogeneous Steel Welds for the Improvement of Ultrasonic Array Inspection, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, Vol: 62, Pages: 1530-1543, ISSN: 0885-3010

JOURNAL ARTICLE

Huthwaite P, Shi F, Van Pamel A, Lowe MJSet al., 2015, High-Speed GPU-Based Finite Element Simulations for NDT, 41st Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE), Publisher: AMER INST PHYSICS, Pages: 1815-1819, ISSN: 0094-243X

CONFERENCE PAPER

Lan B, Lowe MJS, Dunne FPE, 2015, A spherical harmonic approach for the determination of HCP texture from ultrasound: A solution to the inverse problem, JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, Vol: 83, Pages: 179-198, ISSN: 0022-5096

JOURNAL ARTICLE

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