1,586 research outputs found
<a> prismatic, <a> basal, and <c+a> slip strengths of commercially pure Zr by micro-cantilever tests
No full textSlip strengths of <a> basal, <a> prism, and <c+a> pyramidal systems in commercially pure zirconium have been determined using micro-cantilever testing. A range of single crystal cantilevers 0.5 µm to 10 µm wide, oriented for single slip were prepared using focused ion beam (FIB) machining and subsequently deflected using a nanoindenter. The critical resolved shear stress (Ïcrss) was found by fitting a crystal plasticity finite element model to the experimental load-displacement data for these micro-bending tests. All the three slip systems in alpha-Zr show a marked size effect in bending described well by CRSS(W)=Tau0 + AWn, where W is the cantilever width, Tau0 is the CRSS at the macro scale and n=-1. The exponent, n, of near -1 is in good accord with hardening caused by the back stress generated by dislocations piling up at a diffuse barrier caused by the reduction of stress near the neutral axis. The macro scale CRSS values were used to successfully simulate deformation of a conventional macroscopic compression test
PIN, BLACK ANGUS BEEF
No full textImage shows a souvenir pin from the 2002 Olympic Winter Games. The pin consists of an official Certified Angus Beef logo attached to the official Olympic logo, inside an elliptical, blue and black field
HR-EBSD Measurements near Twins in Zicaloy-2
No full textHR-EBSD measurements made on a Zircaloy-2 sample deformed to 2.7% in tension to generate multiple deformation twins.
HR-EBSD measurements were made using A Bruker HReFlash detector mounted on a Zeiss Merlin SEM. Sample preparation used Ar ion beam milling on a Gatan PECS II system as a final step.
The strain, stress and dislocation density variations available here were then calculated using in-house Matlab code (XEBSD) described in the following publications:
High resolution electron backscatter diffraction measurements of elastic strain variations in the presence of larger lattice rotations
TB Britton and AJ Wilkinson
Ultramicroscopy, (2012), vol. 114, 82-95
doi:10.1016/j.ultramic.2012.01.004
Measurement of residual elastic strain and lattice rotations with high resolution electron backscatter diffraction
TB Britton and AJ Wilkinson
Ultramicroscopy, (2011) vol. 111, 1395-1404
doi:10.1016/j.ultramic.2011.05.007
Determination of elastic strain fields and geometrically necessary dislocation distributions near nanoindents using electron back scatter diffraction
AJ Wilkinson and D Randman
Philosophical Magazine, (2010), vol. 90, 1159-1177
doi:10.1080/14786430903304145
Crystal Plasticity Analysis of Micro-Deformation, Lattice Rotation and Geometrically Necessary Dislocation Density
FPE Dunne, R Kiwanuka, AJ Wilkinson
Proc. Royal Society A, (2012), vol. 468, 2509-2531
doi:10.1098/rspa.2012.0050 Stress fields close to twin tips and the associated local neighbourhoods of a hexagonal close-packed (HCP) polycrystal were studied in details. For this purpose, a coarse grain textured Zircaloy-2 sample was firstly strained uniaxially in a macroscopic direction that favours tensile twin formation. The sample was then unloaded and residual elastic strains and lattice rotations measured using the high-resolution electron backscatter diffraction (HR-EBSD) technique. Measured elastic strain maps of various clusters of grains including parent and twin pairs were then analysed. Stress, dislocation density, and their associated concentrations close to twin tips, within twins, in the immediate neighbouring grain, at the intersection of two twins, and within parent grains were investigated. It is shown that the stress field at the twin tips varies as a function of local neighbourhood. High stress, lattice rotation, and dislocation density concentrations were generally observed close to twin tips both within twins and within the immediate neighbouring grains. It is shown dislocation density concentration is maximum at the intersection of two twins which can potentially provide susceptible site for crack nucleation
Autumn leaves : sound and the environment in artistic practice
No full textThis publication is a book that represents an innovative, international and multi-disciplinary approach to conceptualising the dynamic relationships between sound and the environment. The editorial process involved directly commissioning textual, graphic and photographic work. The vast majority of the book represents new work, produced specifically for this publication. For the purposes of tracing historical development, an article from 1974 and three older projects have been revived and recontextualised. In addition to the editorial responsibility, the researcher wrote the introduction and conducted three original interviews. The book draws work from visual, sound and performance art, acoustic science, anthropology, cultural studies, public policy, and architectural theory. Just as it is true to say that these disciplines have not previously been brought together in this way, equally, it is no exaggeration to identify the contributors as the leading international lights in the field: Chris Watson, Tim Ingold, Hildegard Westerkamp, Christina Kubisch, Alvin Lucier, David Toop. The book is published by Double Entendre, the French publisher of the premier sound arts journal, Vibro. The book is accompanied by an audio compilation published by the German record label, Gruenrekorder (Gruen 053). www.autumn-leaves.gruenrekorder.de. The researcher co-curated the compilation, selecting relevant work that illustrated the book’s themes. The book was the catalyst for a one-day symposium at the Tate Britain called The Performance of Sound (May 19th, 2006), which the researcher co-organised. The researcher was invited to speak on the book at the Audio Extranautes: Flux, Distance, Sociability symposium at the Villa Arson in Nice in December 2007. Autumn Leaves has been reviewed in the French journal Mouvement; in MCD where the reviewer reported that “this book deserves to be translated into French”; and Soundscape: The Journal of Acoustic Ecology. Soundscape 7 (1), Autumn, 2007 reprinted an interview conducted by the author from the book. Autumn Leaves, edited by CRiSAP co-director Angus Carlyle, seeks to draw together a number of different perspectives on how the environment is made audible through sound. The perspectives contained in the book are made manifest through more traditional textual analyses, interviews, image-based works (both photography and graphic illustration) and ‘artist’s pages’ (which combine different registers of information).
Among the articles included in the book are a superb deconstruction of the concept of soundscape by anthropologist Tim Ingold; an intriguing analysis of sound from an acoustic point-of-view (or point-of-audition) by Bill Davies; Steve Goodman’s dynamic opening up of city sound to a bass materialism provoked by Greg Lynn’s ‘blob’ architecture; Salome Voegelin’s evocative mapping of sci-fi aesthetics onto the project of acoustic ecology; a wonderful meditation on the heard and the unheard by David Toop; Sylvain Marquis powerfully drawing out the ‘presence’ of Phill Niblock; Rahma Khazam finding new ways of listening through an inspired conceptual conversation between art, architecture and relational aesthetics; and a re-print of Hildegard Westerkamp’s pioneering discussion of soundwalking from 1974.
Interviews include a wide-ranging discussion with Alvin Lucier about his work and working practices; an exploration of Christina Kubisch’s long-standing commitment to teasing out the complexities of the sounds that surround us; Peter Cusack providing an exciting account of his Sound of Dangerous Places project; Chris Watson talking us through his inspirational field-recording; and Max Dixon offering fresh perspectives on how the development of strategies for noise in urban environments meshes policy with research into bio-acoustics, acoustics and creative practice.
Images include Dan Holdsworth’s haunting representations of anechoic chambers through Charles Fox’s photographs of microphone arrays in the wilderness, Axel Stockburger’s ASCII art evocations of video-game space and Nicholas Gansterer’s intricate diagrams of our heard world.
What remains of the book is devoted to the artists’ pages. In these a whole host of contemporary practitioners spanning the disciplines of graphic design, music, photography, performance and visual art offer their provocative takes on sound and the environment. Here we encounter John Wynne and Tim Wainwright presenting their collaborative work in Harefield Hospital; Aki Onda pursuing his Cinemage project; Claudia Wegener finding poetry in ear- and eye-witnessing; an unpacking of the theories and technologies behind the exciting Locus Sonus audio streams; NYSAE opening up its portfolio of acoustic ecology-inspired activities; Goran Vejvoda mobilising a modular manifesto from his three decades of sound art; the Gruenrekorder label reviewing the thinking behind its 40 releases; Jem Finer show-casing his Score For A Hole in the Ground; Cathy Lane mapping her memories of the Hebrides; Zoe Irvine making an art of places out of abandoned audio tape; and Mira Choi introducing her noise-responsive graphic software.
The editorial work and its presentation has been a collaborative venture with the designer Ian Noble.
Autumn Leaves is CRiSAP's first book and is edited by CRiSAP Co-Director Angus Carlyle[/b] and published by the exciting French sound art initiative Vibro / Double Entendre. It contains work by a variety of artists including several of CRiSAP's members - Salomé Voegelin, John Wynne, Peter Cusack, Cathy Lane and David Toop
Review of Mechanisms of strength and hardening in austenitic stainless 310S steel: Nanoindentation experiments and multiscale modeling
No full textThis Zenodo record is a permanently preserved version of a PREreview. You can view the complete PREreview at https://prereview.org/reviews/7371559.
A review of preprint arXiv:2205.03050 [v1] (https://doi.org/10.48550/arXiv.2205.03050)
"Mechanisms of strength and hardening in austenitic stainless 310S steel: Nanoindentation experiments and multiscale modeling"
F. J. Domínguez-Gutiérrez, K. Mulewska, A. Ustrzycka, R. Alvarez-Donado, A. Kosińska, W. Y. Huo, L. Kurpaska, I. Jozwik, S. Papanikolaou, and M. Alava
Reviewer: Angus J Wilkinson
27 November 2022
Overview
The paper presents interesting experimental and molecular dynamics (MD) simulation studies on nanoindention of a face centred cubic Fe-Ni-Cr stainless steel 310S. 310S is high in both Cr (~25wt%) and Ni (~20wt%) compared to other austenitic stainless-steel grades and finds application in areas where high temperature environmental degradation is a concern. A strength of the work is that the high quality of both the nanoindentation experiments and the MD simulations.
The nanoindentation experiments were undertaken with a Berkovich tip with loads in the range 0.25 to 10 mN, so that shallow indents below 200 nm depth resulted. Data for even the smallest <50nm, 0.25nM) indents appeared to be of good quality indicating careful experimentation on difficult measurements. Results from repeat tests are given to indicate noise levels and scatter in material response.
The MD simulations of the 310S alloy were undertaken using LAMMPS with an embedded-atom method (EAM) potential and models with Fe, Ni and Cr atoms in an initially randomised substitutional solid solution. In line with other literature a fixed layer furthest from the indented surface, and a thermostatic layer allowing for heat dissipation were included with the model which was initially equilibrated at 300 K. Given that repeat simulations were conducted for multiple orientations the models size was kept as large as reasonable possible and consisted of a total of 8.5-9 million atoms.
The most significant challenge for the work is in making a strong connection between the experiments and simulations when computational resource prohibits using a larger model, while experimental uncertainties are more marked for smaller indents. The dilemma is perhaps made most evident by comparing the 10 nm tip radius and 5 nm maximum indent depth used in the simulations with the smallest experimental indents of a little under 50 nm. A more fundamental barrier to direct comparison is that the simulations are for tip radius of 10 nm, while the experiments are for much larger value (~100 nm seems likely from load-displacement data though the actual value is not quoted). The larger tip radius in the experiments provides access to much larger indentation strains than is possible in the simulations, while larger strain gradients are in place for the simulations. Finally, there is a large difference in loading rate (and therefore deformation rate).
Reading the preprint provoked the following comments and questions some of which might be useful to the authors.
Main Points
· Given the challenges above in making direct comparisons the conclusion of excellent agreement between experiment and simulation should perhaps be softened, similarly the work itself does not deal with high temperature behaviour, or effects of irradiation so conclusions regarding the suitability of the alloy for nuclear applications seem out of scope.
· The attempt to estimate GND density is interesting, especially as the strain gradients are extremely high for the simulations, and quite a bit lower for the experiments. Typically, a length scale needs to be set in describing how the total dislocation density is split between GND and SSD densities, but this has not been made explicit here. For the MD simulations it may be that all dislocations have been taken to contribute to the GND density, but it is not clear what volume term has been used (text around eq 12-13 suggests contact diameter may be the indicative lengthscale). For the Ma-Clarke model how was the shear strain calculated (the Ma-Clarke paper was for Berkovich rather than spherical indents)? No details are given for the calculation of GND density from the EBSD map, but the characteristic lengthscale is likely markedly larger than for the MD simulation, and the effects of this should be discussed. A little more detail in methodologies should be given for all of this analysis. Fig 11 c) is the only figure where both simulation and experimental data are shown directly on the same plot. Ma & Clarke (and subsequently Nix & Gao) used both SSD and GND densities as contributions to a Taylor hardening expression to link strain gradients to indentation size effects. Have the authors thought of extended their analysis to see if this can consistently link the markedly lower hardness values seen for deeper experimental indents with the much higher hardness reported for MD simulations?
· Some interesting dislocation density-based laws are introduced in eq 8 to 10. These are fit to the MD simulation results for dislocation density in fig 8a. It would be good to state the dislocation mean free path and annihilation constants obtained. As with the point above can a Taylor hardening model then be used to connect to hardness values and then provide a link to the experimental data. [In passing the text describing eq 10 refers to grain size though perhaps indent size is more relevant here].
· Results from simulations and experiments show relatively little anisotropy in either indentation modulus or hardness (eg figs 4b, fig 5, fig 8b) – it seems odd then to state in the conclusions that "…310S indicates anisotropic properties…".
Minor Points
· Caption on fig 4 swaps parts (a) and (b)
· Scale bars should be added to fig 6, fig 7 a and b, fig 9, fig 11a and b, and fig 12
· Fig 9b – the 5nm and unload images seem to be identical though difference are talked about in the main text.
Angus J Wilkinson
27 November 202
HR-EBSD Measurements near Twins in Zicaloy-2
No full text<p>HR-EBSD measurements made on a Zircaloy-2 sample deformed to 2.7% in tension to generate multiple deformation twins. <br />
HR-EBSD measurements were made using A Bruker HReFlash detector mounted on a Zeiss Merlin SEM. Sample preparation used Ar ion beam milling on a Gatan PECS II system as a final step. <br />
The strain, stress and dislocation density variations available here were then calculated using in-house Matlab code (XEBSD). The work and further analysis of the results is described in</p>
<p><em>Assessment of residual stress fields at deformation twin tips and the surrounding environments</em>, Abdolvand & Wilkinson, Acta Materialia (2016)<br />
dx.doi.org/10.1016/j.actamat.2015.11.036</p>
<p> </p>
<p> </p>
<p>The analysis methods implement in XEBSD are described in the following publications:</p>
<p>High resolution electron backscatter diffraction measurements of elastic strain variations in the presence of larger lattice rotations <br />
TB Britton and AJ Wilkinson <br />
Ultramicroscopy, (2012), vol. 114, 82-95 <br />
doi:10.1016/j.ultramic.2012.01.004</p>
<p>Measurement of residual elastic strain and lattice rotations with high resolution electron backscatter diffraction <br />
TB Britton and AJ Wilkinson <br />
Ultramicroscopy, (2011) vol. 111, 1395-1404 <br />
doi:10.1016/j.ultramic.2011.05.007</p>
<p>Determination of elastic strain fields and geometrically necessary dislocation distributions near nanoindents using electron back scatter diffraction <br />
AJ Wilkinson and D Randman <br />
Philosophical Magazine, (2010), vol. 90, 1159-1177 <br />
doi:10.1080/14786430903304145</p>
<p>Crystal Plasticity Analysis of Micro-Deformation, Lattice Rotation and Geometrically Necessary Dislocation Density <br />
FPE Dunne, R Kiwanuka, AJ Wilkinson <br />
Proc. Royal Society A, (2012), vol. 468, 2509-2531 <br />
doi:10.1098/rspa.2012.0050</p>
Corrigendum to “A mechanistic study of the temperature dependence of the stress corrosion crack growth rate in SUS316 stainless steels exposed to pressurized water reactor primary water” [Acta Mater. 114 (2016) 15–24]
No full textThe authors regret that one of the main contributors to this paper was unintentionally omitted from the author list in the final version of the manuscript. The complete author list should read: Martina Meisnara, Arantxa Vilalta-Clementea, Michael Moodya, Angus J. Wilkinsona, Koji Ariokab, Sergio Lozano-Pereza,∗ The authors would like to apologise for any inconvenience caused
Height, health, and inequality: the distribution of adult heights in India
No full textThis paper explores the relationship between adult heights and the distribution of income across populations of individuals. There is a long literature that examines the relationship between mean adult heights and living standards. If adult height is set by the balance between food intake and charges to disease in early childhood, it is informative about economic and epidemiological conditions in childhood. Because taller populations are better-off, more productive, and live longer, the relationship between childhood conditions and adult height has become an important focus in the study of the relationship between health and wealth. Here I follow one of the tributaries of this main stream. A relationship between income and height at the individual level has implications for the effects of income inequality on the distribution of heights. These relationships parallel, but are somewhat more concrete than, the various relationships between income inequality and health that have been debated in the economic and epidemiological literatures, Richard G. Wilkinson (1996), Angus Deaton (2003).
The forgotten first: John MacCormick's 'Dùn-Àluinn'
No full textThe first Gaelic novel, John MacCormick's Dùn-Àluinn, no an t-Oighre 'na Dhìobarach, was serialised in the People's Journal in 1910 before being published in its entirety in 1912. Within a year of the publication of Dùn-Àluinn as a novel the second Gaelic novel, Angus Robertson's An t-Ogha Mòr, appeared in print, underlining the renaissance which Gaelic literature was experiencing. Both novels, while remarked upon by contemporaries and by general studies of Gaelic literature, have been all but ignored to date, with no criticism or analysis of either having been published. The main aim of this article is to offer some general comments about MacCormick's Dùn-Àluinn and thus to open up both the novel and indeed other early twentieth-century Gaelic writers and their work to further scrutiny. Consideration will be given to the author himself, the contemporary Gaelic literary scene and finally some of the more interesting aspects of the novel itself
An accountability model for Pakeha practitioners
No full textThis paper outlines a model of accountability for Pakeha practitioners developed over many years
as a practising community psychologist involved in research and development projects in Aotearoa
in the 1980s and 1990s, during an era of contract-funded health projects, and increasing
prominence of the Treaty of Waitangi2. The model could be termed 'transformative' in that it
reverses the usual flow of power by making the Pakeha practitioner accountable to relevant Maori
authority, and maximises the potential for new outcomes and new learning for all parties. A brief
case study is outlined where the model placed a local iwi governance structure and a national
psychiatric survivor organisation in positions of authority alongside the funder of a mental health
project. Helpful conditions, positive outcomes and barriers to transformative accountability
processes are briefly discussed
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