Matthew R Arthington | University of Oxford (original) (raw)

Papers by Matthew R Arthington

7th IET Conference on Railway Condition Monitoring 2016 (RCM 2016)

Network Rail's Western Route is undergoing a wide-ranging modernisation programme, with £7.5bn in... more Network Rail's Western Route is undergoing a wide-ranging modernisation programme, with £7.5bn investment in 175 miles of electrification and infrastructure upgrades allowing the introduction of four new fleets of train by 2019. This paper reviews the potential utilisation of camera imagery to inform maintenance processes that need to absorb a step change in pantograph movements and OLE management.

Ring-rolling is an industrial forming process to produce high-strength metal rings up to 6m diame... more Ring-rolling is an industrial forming process to produce high-strength metal rings up to 6m diameter. Thickwalled cylindrical workpieces of material, typically metallic alloys, are compressed between two or more internal and external rollers and rotated until a target geometry, often outer diameter, is achieved. The process is inherently unstable and the process is often constrained and/or controlled to improve its stability. This paper presents an image processing algorithm for the measurement of ring geometry through photogrammetry in real-time. These measurements will form part of the feedback control system for a ring-rolling process. An off-the-shelf USB webcam is used to capture images of the ring during forming and the scene is controlled to maximise contrast and minimise occlusions of the ring. The image processing tasks include object identification, edge detection, outlier rejection and distortion rectification. The process has been implemented on a desktopscale forming ma...

2015 IEEE Conference on Control Applications (CCA), 2015

Ring-rolling is an industrial forming process for producing high-strength seamless metal rings up... more Ring-rolling is an industrial forming process for producing high-strength seamless metal rings up to 6m diameter. Thick-walled cylindrical rings of material, typically metallic alloys, are compressed between two or more internal and external rollers and rotated until a target geometry, often outer diameter, is achieved. A common plant configuration is that of a pair of radially acting rollers and a pair of axial rollers, the radial-axial ring rolling (RARR) machine. The most commonly produced product geometries have an axisymmetric cross-section profile. However, during the forming process the cross section is changed significantly as it passes through each pair of rollers. This irregular shape hinders geometry state measurement and this complicates modelling and control of the process. Recent developments in sensing capabilities offer high resolution measurement of ring geometry during forming. In this work, we present advances in these sensing techniques, a numerical method for storing and predicting the ring's geometrical state and control laws to achieve a nonaxisymmetric cross-section profile in rolled rings using existing RARR plant hardware.

Impact Engineering Team Solid Mechanics and Materials Group Department of Engineering Science Uni... more Impact Engineering Team Solid Mechanics and Materials Group Department of Engineering Science University of Oxford, Parks Road, Oxford matthew. arthington@ eng. ox. ac. uk, http://www. eng. ox. ac. uk/NP/iet. html Key Words: Anisotropic, computer vision, reconstruction, high strain rates.

DYMAT 2009 - 9th International Conferences on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, 2009

Two methods for the improved characterisation of anisotropic materials are presented. One method ... more Two methods for the improved characterisation of anisotropic materials are presented. One method utilises three optical videos of cylindrical specimens undergoing uniaxial loading to reconstruct elliptical cross-sectional contours. This information can be used to improve knowledge of anisotropic plastic deformation behaviour. A second method uses digital images of specimens to perform the task of a video extensometer. Through the high resolution imaging of specimens, the undulations due to machining can be seen in edges detected to sub-pixel accuracy. These edges have unique variations along their length that may be tracked to provide high density strain data without occlusions due to the marking required by other methods. The cross-section reconstruction has been applied to rolled Ti64 at strain rates of ~10-3 s-1 , ~1s-1 and ~10 3 s-1 in compression and tension experiments. Three views have been obtained using both multiple camera rigs and mirrors. The strain measurement through edge tracking has been applied to specimens loaded at ~10-3 s-1 using high resolution imaging.

The Journal of Strain Analysis for Engineering Design, 2010

This paper presents a novel approach to the classic Taylor impact experiment using an ultra-high-... more This paper presents a novel approach to the classic Taylor impact experiment using an ultra-high-speed camera and mirror arrangement to measure the elliptical cross-section of a specimen in situ as a function of time. This optical measurement technique is used to quantify the key aspects of material behaviour, such as the area strain perpendicular to the impact direction and the lengths of the semimajor and semiminor axes of the elliptical sample cross-section, which were caused by anisotropic plastic deformation, as functions of time and the axial position. The application of this technique gives access to previously unattainable data on the anisotropic plastic deformation of Taylor impact specimens and therefore has the potential to provide a more rigorous method of validation for anisotropic constitutive material models. To demonstrate the feasibility of the new method, experiments were carried out on cylindrical Taylor impact specimens machined from strongly textured high-purity zirconium plate. The surface geometry of a recovered specimen was measured using a coordinate measurement machine and compared with the optically measured surface geometry reconstructed from post-impact images. Excellent agreement between the two methods was found.

International Journal of Impact Engineering, 2012

DYMAT 2009 - 9th International Conferences on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, 2009

Abstract. This paper describes results from Taylor impact experiments on specimens cut from a Ti-... more Abstract. This paper describes results from Taylor impact experiments on specimens cut from a Ti-6Al-4V plate. High-speed photography and a mirror arrangement are used to obtain images of the specimen from three views. The positions of the edges of the specimen in these images are then used to fully reconstruct the specimen surface in 3D, allowing the real-time anisotropic deformation of the specimen to be studied. Further to this, the traditional anvil used in Taylor impact experiments has been replaced with an ...

Measurement Science and Technology, 2011

The principal aims of this research have been the development of photogrammetric techniques for t... more The principal aims of this research have been the development of photogrammetric techniques for the measurement of anisotropic deformation in uniaxially loaded cylindrical specimens. This has been achieved through the use of calibrated cameras and the application of edge detection and multiple view geometry. The techniques have been demonstrated at quasi-static strain rates, 10^-3 s^-1, using a screw-driven loading device and high strain rates, 10^3 s^-1, using Split Hopkinson Bars. The materials that have been measured using the technique are nearlyisotropic steel, anisotropic cross-rolled Ti-6Al-4V and anisotropic clock-rolled commercially pure Zr. These techniques allow the surface shapes of specimens that deform elliptically to be completely tracked and measured in situ during loading. This has allowed the measurement of properties that could not have been recorded before, including true direct stress and the ratio of transverse strains in principal material directions, at quasi...

Journal of Dynamic Behavior of Materials, 2015

A cross-rolled plate of the industrially important titanium alloy, Ti-6Al-4V, has been microstruc... more A cross-rolled plate of the industrially important titanium alloy, Ti-6Al-4V, has been microstructurally and mechanically characterised using a range of different experimental techniques. The microstructure of the material has been studied using backscatter electron (BSE) microscopy and electron backscatter diffraction (EBSD), with the crystallographic orientation data from the EBSD used to reconstruct the orientation distribution function of the dominant a phase. The mechanical behaviour of the material has been investigated at quasi-static and high strain rates in the three orthogonal material orientations in both tension and compression. A novel in situ optical measurement technique has been used to measure the geometry of the specimens during both quasi-static and high strain rate mechanical testing, improving the accuracy of the mechanical testing results and providing unprecedented information about the evolving geometries of the specimens. The macroscopic stress-strain response and the evolution of specimen cross-sectional profiles have been qualitatively linked to the macroscopic crystallographic texture in the plate.

CIRP Annals

Ring rolling processes today produce axisymmetric rings, wasting material, energy and labour if n... more Ring rolling processes today produce axisymmetric rings, wasting material, energy and labour if non-axisymmetric components such as eccentric bearing races and bossed pipe fittings are required. A new process is proposed to roll rings with variable wall thickness. In this work, roll gaps and speeds are controlled online in physical experiments to achieve a defined variable wall thickness, enabled by photogrammetry to capture the ring's shape and position. The trials revealed two new process limits for which new analytical explanations have been developed: a maximum rate of change of thickness around the circumference and a loss of circularity. Rolling, Process-Control, Ring Rolling.

CIRP Annals

IFAC-PapersOnLine

Radial-axial ring rolling (RARR) is an industrial forging process that produces seamless metal ri... more Radial-axial ring rolling (RARR) is an industrial forging process that produces seamless metal rings with uniform cross-section using one radial and one axial rolling stage. Conventionally, the ring products are circular and the process is tightly constrained using guide rolls for stability, and to ensure the circularity and uniformity of the ring. Recent work has shown that when guide rolls are omitted, stability can be maintained using differential speed control of the roll pairs. However, achieving uniform curvature in this unconstrained configuration was not always possible when the controller only centred the ring within the rolling mill. In addition to the regulation of constant curvature in circular rings, differential speed control in unconstrained rolling offers an opportunity to bend the ring about the mandrel to create shapes with nonuniform curvature, for example: squares, hexagons, rings with flat sections, etc. We describe a control technique for creating non-circular rings using the rolling hardware of a conventional RARR mill, machine-vision sensing and differential speed control of the rolling stages. The technique has been validated for an industrial material in numerical simulations using the finite element method and also demonstrated on a desktop-scale RARR mill using modelling clay to simulate metal at elevated process temperatures.

2014 UKACC International Conference on Control (CONTROL), 2014

International Journal of Material Forming

Radial-Axial Ring Rolling (RARR) is an industrial forging process for making strong, seamless met... more Radial-Axial Ring Rolling (RARR) is an industrial forging process for making strong, seamless metal rings. Conventionally, rings are made circular with constant cross-section. In this work we demonstrate a sensing and control strategy to create rings with variable radial wall thickness and variable curvature using standard RARR hardware. This has a number of potentially useful applications but also provides an understanding of how to control these properties for conventional RARR. The sensing uses a calibrated video camera to take a series of images of the ring top surface. Image processing is employed to measure and track the ring material in-situ. The complete state of the ring is represented by the ring thickness and curvature as a function of its volume fraction, which is computed by combining the measurements from the unoccluded areas with estimates of the ring shape elsewhere. Additionally, we present a marking technique for tracking of material as it rotates through the rolling machine, even after significant deformation of the ring has occurred. We show that rings with a wide range of variation in local thickness and curvature can be formed using conventional RARR hardware and a photogrammetric state measurement technique, combined with open-loop scheduling and feedback control of thickness and curvature. Rings with both variable thickness and non-circular shapes have been produced virtually using numerical simulations and in reality using modelling clay as a material to simulate metals at forging temperatures. We demonstrate that this technique extends the range of shapes achievable with standard RARR hardware.

1Impact Engineering Team, Solid Mechanics and Materials Engineering Group, Department of Engineer... more 1Impact Engineering Team, Solid Mechanics and Materials Engineering Group, Department of Engineering Science, University of Oxford Parks Road, Oxford OX1 3PJ, UK Nik.Petrinic@eng.ox.ac.uk Helen.Sarsfield@eng.ox.ac.uk Matthew.Arthington@eng.ox.ac.uk www.eng.ox.ac.uk ... 2Rolls-Royce plc PO Box 31, Derby DE24 8BJ, UK Julian.Reed@rolls-royce .com www.rolls-royce.com ... Key Words: Titanium alloy, Mechanical behaviour, Microstructure, Crystal plasticity, Continuum plasticity, Plastic spin. ... Advanced materials ...

The Journal of Strain Analysis for Engineering Design, 2010

This paper presents a novel approach to the classic Taylor impact experiment using an ultra-high-... more This paper presents a novel approach to the classic Taylor impact experiment using an ultra-high-speed camera and mirror arrangement to measure the elliptical cross-section of a specimen in situ as a function of time. This optical measurement technique is used to quantify the key aspects of material behaviour, such as the area strain perpendicular to the impact direction and the lengths of the semimajor and semiminor axes of the elliptical sample crosssection, which were caused by anisotropic plastic deformation, as functions of time and the axial position. The application of this technique gives access to previously unattainable data on the anisotropic plastic deformation of Taylor impact specimens and therefore has the potential to provide a more rigorous method of validation for anisotropic constitutive material models. To demonstrate the feasibility of the new method, experiments were carried out on cylindrical Taylor impact specimens machined from strongly textured high-purity zirconium plate. The surface geometry of a recovered specimen was measured using a coordinate measurement machine and compared with the optically measured surface geometry reconstructed from post-impact images. Excellent agreement between the two methods was found.

DYMAT 2009 - 9th International Conferences on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, 2009

Two methods for the improved characterisation of anisotropic materials are presented. One method ... more Two methods for the improved characterisation of anisotropic materials are presented. One method utilises three optical videos of cylindrical specimens undergoing uniaxial loading to reconstruct elliptical cross-sectional contours. This information can be used to improve knowledge of anisotropic plastic deformation behaviour. A second method uses digital images of specimens to perform the task of a video extensometer. Through the high resolution imaging of specimens, the undulations due to machining can be seen in edges detected to sub-pixel accuracy. These edges have unique variations along their length that may be tracked to provide high density strain data without occlusions due to the marking required by other methods. The cross-section reconstruction has been applied to rolled Ti64 at strain rates of y10 x3 s x1 , y1 s x1 and y10 3 s x1 in compression and tension experiments. Three views have been obtained using both multiple camera rigs and mirrors. The strain measurement through edge tracking has been applied to specimens loaded at y10 x3 s x1 using high resolution imaging.

7th IET Conference on Railway Condition Monitoring 2016 (RCM 2016)

2015 IEEE Conference on Control Applications (CCA), 2015

DYMAT 2009 - 9th International Conferences on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, 2009

The Journal of Strain Analysis for Engineering Design, 2010

International Journal of Impact Engineering, 2012

DYMAT 2009 - 9th International Conferences on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, 2009

Measurement Science and Technology, 2011

Journal of Dynamic Behavior of Materials, 2015

CIRP Annals

IFAC-PapersOnLine

2014 UKACC International Conference on Control (CONTROL), 2014

International Journal of Material Forming

The Journal of Strain Analysis for Engineering Design, 2010

This paper presents a novel approach to the classic Taylor impact experiment using an ultra-high-... more This paper presents a novel approach to the classic Taylor impact experiment using an ultra-high-speed camera and mirror arrangement to measure the elliptical cross-section of a specimen in situ as a function of time. This optical measurement technique is used to quantify the key aspects of material behaviour, such as the area strain perpendicular to the impact direction and the lengths of the semimajor and semiminor axes of the elliptical sample crosssection, which were caused by anisotropic plastic deformation, as functions of time and the axial position. The application of this technique gives access to previously unattainable data on the anisotropic plastic deformation of Taylor impact specimens and therefore has the potential to provide a more rigorous method of validation for anisotropic constitutive material models. To demonstrate the feasibility of the new method, experiments were carried out on cylindrical Taylor impact specimens machined from strongly textured high-purity zirconium plate. The surface geometry of a recovered specimen was measured using a coordinate measurement machine and compared with the optically measured surface geometry reconstructed from post-impact images. Excellent agreement between the two methods was found.

DYMAT 2009 - 9th International Conferences on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, 2009

Two methods for the improved characterisation of anisotropic materials are presented. One method ... more Two methods for the improved characterisation of anisotropic materials are presented. One method utilises three optical videos of cylindrical specimens undergoing uniaxial loading to reconstruct elliptical cross-sectional contours. This information can be used to improve knowledge of anisotropic plastic deformation behaviour. A second method uses digital images of specimens to perform the task of a video extensometer. Through the high resolution imaging of specimens, the undulations due to machining can be seen in edges detected to sub-pixel accuracy. These edges have unique variations along their length that may be tracked to provide high density strain data without occlusions due to the marking required by other methods. The cross-section reconstruction has been applied to rolled Ti64 at strain rates of y10 x3 s x1 , y1 s x1 and y10 3 s x1 in compression and tension experiments. Three views have been obtained using both multiple camera rigs and mirrors. The strain measurement through edge tracking has been applied to specimens loaded at y10 x3 s x1 using high resolution imaging.