I12-JEEP: Joint Engineering, Environmental and Processing
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A.
Koko
,
S.
Singh
,
S.
Barhli
,
T.
Connolley
,
N. T.
Vo
,
T.
Wigger
,
D.
Liu
,
Y.
Fu
,
J.
Réthoré
,
J.
Lechambre
,
J.-Y.
Buffiere
,
T. J.
Marrow
Diamond Proposal Number(s):
[12585]
Open Access
Abstract: The propagation rate of a fatigue crack in a nodular cast iron, loaded in cyclic tension, has been studied in situ by X-ray computed tomography and digital volume correlation. The semi-elliptical crack initiated from an asymmetric corner notch and evolved to a semi-circular shape, initially with a higher growth rate towards one edge of the notch before the propagation rate along the crack front became essentially independent of po-sition. The phase congruency of the displacement field was used to measure the crack shape. The three-dimensional stress intensity factors were calculated via a linear elastic finite element model that used the displacement fields around the crack front as the boundary conditions. Closure of the crack tip region was observed. The cyclic change in the local mode I opening of the crack tip determined the local fatigue crack propaga-tion rate along the crack front.
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May 2023
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[20096]
Open Access
Abstract: Laser additive manufacturing is transforming several industrial sectors, especially the directed energy deposition process. A key challenge in the widespread uptake of this emerging technology is the formation of undesirable microstructural features such as pores, cracks, and large epitaxial grains. The trial and error approach to establish the relationship between process parameters and material properties is problematic due to the transient nature of the process and the number of parameters involved. In this work, the relationship between process parameters, melt pool geometry and quality of build measures, using directed energy deposition additive manufacturing for IN718, is quantified using neural networks as generalised regressors in a statistically robust manner. The data was acquired using in-situ synchrotron x-ray imaging providing unique and accurate measurements for our analysis. An analysis of the variations across repeated measurements show heteroscedastic error characteristics that are accounted for using a principled nonlinear data transformation method. The results of the analysis show that surface roughness correlates with melt pool geometry while the track height directly correlates with process parameters indicating a potential to directly control efficiency and layer thickness while independently minimising surface roughness.
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Mar 2023
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B16-Test Beamline
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Diamond Proposal Number(s):
[7440]
Abstract: Dendrites are the most common microstructural features in the cast metals, significantly affecting the structure integrity and mechanical properties of the castings. In this study, the in situ synchrotron X-ray radiographic and tomographic imaging techniques were combined to evaluate the critical fracture stress of the growing dendrite tip during the solidification of an Al-15 wt% Cu alloy under an external electromagnetic force. Two dendritic 3D models have been proposed to simulate the dendrite 3D morphologic characteristics and thus revealed that the critical fracture stresses of the Al dendrites at temperatures close to its melting point were in the range of 0.5 kPa–0.05 MPa. The present results demonstrate the feasibility of measuring the high-temperature mechanical properties of the metallic dendrites.
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Feb 2023
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I12-JEEP: Joint Engineering, Environmental and Processing
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Open Access
Abstract: Deformation bands, or tabular zones of localised strain, are a common manifestation of deformation in upper crustal sedimentary rocks. Any mining or energy-related engineering applications must consider the possibility of reactivating these pre-existing failure planes because doing so can cause seismicity and compartmentalise the reservoir. However, there has only been a small amount of research done on laboratory-induced deformation in rocks with natural deformation features.
On a low porosity bioclastic calcarenite from the Cotiella Basin, Spanish Pyrenees, our current experimental work aims to capture, for the first time to our knowledge, the dominant failure mechanisms during the reactivation of natural deformation bands oriented at different angles to the principal stress direction. At the I12-JEEP beamline at the synchrotron facility of Diamond Light Source, UK, we carried out triaxial compression experiments using a modified version of the Mjolnir cell used by Cartwright-Taylor et al., (2022) to examine how these highly heterogeneous rocks respond to additional mechanical deformation. During the deformation experiments, 4D (time and space) x-ray tomography images (8 m voxel size resolution) were acquired. We tested confining pressures between 10 MPa and 30 MPa.
The mechanical data demonstrate that the existence of natural deformation features within the tested samples weakens the material. For instance, solid samples of the host rock subjected to the same confining pressures had higher peak differential stresses. Additionally, our findings demonstrate that new deformation bands form as their angle, θ, to σ1 increases, while the reactivation of pre-exiting deformation bands in this low porosity carbonate only occurs for dipping angles close to 70o. The spatio-temporal relationships between the naturally occurring and laboratory-induced deformation bands and fractures were investigated using time-resolved x-ray tomography and Digital Volume Correlation (DVC). Volumetric and shear strain fields were calculated using the SPAM software (Stamati et al., 2020). The orientation of the recently formed failure planes is influenced by the orientation of the pre-existing bands, as well as their width and the presence (or absence) of porosity along their length. Additionally, pre-existing secondary deformation features found in the tested material trigger additional mechanical damage that either promotes the development or deflects the new failure planes.
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Feb 2023
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[29710]
Open Access
Abstract: The origin of jaws and teeth remains contentious in vertebrate evolution. ‘Placoderms’ (Silurian-Devonian armoured jawed fishes) are central to debates on the origins of these anatomical structures. ‘Acanthothoracids’ are generally considered the most primitive ‘placoderms’. However, they are so far known mainly from disarticulated skeletal elements that are typically incomplete. The structure of the jaws—particularly the jaw hinge—is poorly known, leaving open questions about their jaw function and comparison with other placoderms and modern gnathostomes. Here we describe a near-complete ‘acanthothoracid’ upper jaw, allowing us to reconstruct the likely orientation and angle of the bite and compare its morphology with that of other known ‘placoderm’ groups. We clarify that the bite position is located on the upper jaw cartilage rather than on the dermal cheek and thus show that there is a highly conserved bite morphology among most groups of ‘placoderms’, regardless of their overall cranial geometry. Incorporation of the dermal skeleton appears to provide a sound biomechanical basis for jaw origins. It appears that ‘acanthothoracid’ dentitions were fundamentally similar in location to that of arthrodire ‘placoderms’, rather than resembling bony fishes. Irrespective of current phylogenetic uncertainty, the new data here resolve the likely general condition for ‘placoderms’ as a whole, and as such, ancestral morphology of known jawed vertebrates.
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Feb 2023
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I13-1-Coherence
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Diamond Proposal Number(s):
[28831]
Open Access
Abstract: Diffractive optical elements such as periodic gratings are fundamental devices in X-ray imaging – a technique that medical, material science, and security scans rely upon. Fabrication of such structures with high aspect ratios at the nanoscale creates opportunities to further advance such applications, especially in terms of relaxing X-ray source coherence requirements. This is because typical grating-based X-ray phase imaging techniques (e.g., Talbot self-imaging) require a coherence length of at least one grating period and ideally longer. In this paper, the fabrication challenges in achieving high-aspect ratio nanogratings filled with gold are addressed by a combination of laser interference and nanoimprint lithography, physical vapor deposition, metal assisted chemical etching (MACE), and electroplating. This relatively simple and cost-efficient approach is unlocked by an innovative post-MACE drying step with hexamethyldisilazane, which effectively minimizes the stiction of the nanostructures. The theoretical limits of the approach are discussed and, experimentally, X-ray nanogratings with aspect ratios >40 are demonstrated. Finally, their excellent diffractive abilities are shown when exposed to a hard (12.2 keV) monochromatic X-ray beam at a synchrotron facility, and thus potential applicability in phase-based X-ray imaging.
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Jan 2023
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I14-Hard X-ray Nanoprobe
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Ian
Byrnes
,
Lisa Magdalena
Rossbach
,
Jakub
Jaroszewicz
,
Daniel
Grolimund
,
Dario
Ferreira Sanchez
,
Miguel A.
Gomez-Gonzalez
,
Gert
Nuyts
,
Estela
Reinoso-Maset
,
Koen
Janssens
,
Brit
Salbu
,
Dag Anders
Brede
,
Ole Christian
Lind
Diamond Proposal Number(s):
[27615]
Open Access
Abstract: Micro- and nanoscopic X-ray techniques were used to investigate the relationship between uranium (U) tissue distributions and adverse effects to the digestive tract of aquatic model organism Daphnia magna following uranium nanoparticle (UNP) exposure. X-ray absorption computed tomography measurements of intact daphnids exposed to sublethal concentrations of UNPs or a U reference solution (URef) showed adverse morphological changes to the midgut and the hepatic ceca. Histological analyses of exposed organisms revealed a high proportion of abnormal and irregularly shaped intestinal epithelial cells. Disruption of the hepatic ceca and midgut epithelial tissues implied digestive functions and intestinal barriers were compromised. Synchrotron-based micro X-ray fluorescence (XRF) elemental mapping identified U co-localized with morphological changes, with substantial accumulation of U in the lumen as well as in the epithelial tissues. Utilizing high-resolution nano-XRF, 400–1000 nm sized U particulates could be identified throughout the midgut and within hepatic ceca cells, coinciding with tissue damages. The results highlight disruption of intestinal function as an important mode of action of acute U toxicity in D. magna and that midgut epithelial cells as well as the hepatic ceca are key target organs.
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Jan 2023
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I13-2-Diamond Manchester Imaging
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Abstract: Accurately estimating developmental age and life history traits in fossils is crucial for identifying
and classifying extinct species and understanding how biological attributes evolved. The
evolution of life history traits such as growth pattern is far from clear in birds, and development
has been studied in only a handful of modern species. The exceptionally rapid growth of
modern birds means ageing methods based on annual incremental growth lines, used in other
vertebrates, are inapplicable to birds and robust alternative methods remain to be established.
Analysis of avian intracortical bone microstructure, which varies both with age and tissue
deposition rate, is a promising approach already used in palaeobiology. However, current thin
section-based histological methods are destructive. Moreover, to date, most microstructural
studies in avian bone are qualitative, 2D, and involve a limited range of extant species. The
objective of this study was to investigate cortical bone microstructure and developmental age
and life history traits in living birds, to identify phenotypes which can then be applied to
examination of the fossil record, using minimally-destructive high-resolution 3D imaging.
First, the necessity of 3D measurement was tested: a combination of idealised, simulated
datasets and real synchrotron-based computed tomography (SR CT) datasets were used to
compare published methods for measuring key microstructural traits based on 2D sections and
3D volumes. Next, SR CT imaging and quantitative measurements were used to characterise
age-related changes in bone microstructure in a range of extant bird species: growth series
ducks and pheasants, and a smaller sample size in starlings, rock doves, partridges, and ostrich.
The methods tested in modern material were applied to fossils as a proof-of concept.
It was found that 3D quantification methods are required for measuring vascular canal
orientation and osteocyte lacunar shape and volume, though 2D sections could be used to
measure traits such as bone volume fraction (BV/TV) and osteocyte lacunar volume. In all
species studied, juvenile, subadult, and adult species could be distinguished by their values of
BV/TV, and further information could be added using measured values of vascular canal
diameter as well as qualitative assessment. Using a synchrotron-based CT system,
high-resolution 3D datasets comparable to modern bone samples were obtained from fossils,
and preliminary estimates of developmental age can be made.
Further work may reveal more changes within juvenile age stages, and better characterise the
variation within extant birds, allowing more accurate interpretation of the fossil record.
Therefore developmental studies in a greater number of extant bird species are required using
larger sample sizes, to support and add to the results presented in this thesis.
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Jan 2023
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[20611]
Open Access
Abstract: Arc welding is one of the widely used approaches for joining metals. During the arc welding process, an electric arc creates intense heat to fuse metals that forms the melt pool between the parts to be welded together. Intensive flow fields are observable within the fusion weld pools as a result of multiple driving forces. The flow patterns within the melt pool significantly determine the shape of the weld joint and other attributes of the solidified joint, such as microstructure and defects. Porosity is one of the solidification-related defects that can bring a detrimental impact. During the formation and solidification of weld pools, gas bubbles that are formed can be driven in or out from the pool by the flow. In this work, employing in situ synchrotron X-rays, we have observed how different flow conditions and air-liquid interface are contributed to retaining and releasing the gas bubbles that formed during the arc welding. The results suggest that underpinning driving forces, such as electromagnetic forces, act on molten metal to retain the pores inside the weld joints; but, gravity-driven effects can contribute to reduce the porosity, with appropriate process conditions
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Jan 2023
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I14-Hard X-ray Nanoprobe
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Diamond Proposal Number(s):
[28142]
Open Access
Abstract: The interaction of a focused X-ray beam with a sample in a scanning probe experiment can provide a variety of information about the interaction volume. In many scanning probe experiments X-ray fluorescence (XRF) is supplemented with measurements of the transmitted or scattered intensity using a pixelated detector. The automated extraction of different signals from an area pixelated detector is described, in particular the methodology for extracting differential phase contrast (DPC) is demonstrated and different processing methods are compared across a range of samples. The phase shift of the transmitted X-ray beam by the sample, extracted from DPC, is also compared with ptychography measurements to provide a qualitative and quantitative comparison. While ptychography produces a superior image, DPC can offer a simple, flexible method for phase contrast imaging which can provide fast results and feedback during an experiment; furthermore, for many science problems, such as registration of XRF in a lighter matrix, DPC can provide sufficient information to meet the experimental aims. As the DPC technique is a quantitative measurement, it can be expanded to spectroscopic studies and a demonstration of DPC for spectro-microscopy measurements is presented. Where ptychography can separate the absorption and phase shifts by the sample, quantitative interpretation of a DPC image or spectro-microscopy signal can only be performed directly when absorption is negligible or where the absorption contribution is known and the contributions can be fitted.
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Dec 2022
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