136 results on '"X-ray Computed Tomography (XCT)"'
Search Results
2. Quantifying the effect of scanning parameters on digital volume correlation analysis for in situ X-ray imaging of concrete
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Paraskevoulakos, Charilaos, Kunther, Wolfgang, and Michel, Alexander
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- 2024
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3. Mesostructural evolution of fine-aggregate bitumen emulsion–cement composites by X-ray tomography.
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Miljković, Miomir, Griffa, Michele, Münch, Beat, Plamondon, Mathieu, and Lura, Pietro
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COMPUTED tomography , *IMAGE analysis , *PARTICLE size distribution , *X-rays , *TOMOGRAPHY - Abstract
This research quantified the temporal mesostructural evolution of bitumen emulsion–cement composites using the time-lapse high-energy X-ray tomography of a fine-aggregate matrix. The image post-processing and analysis showed that the mastic's significant temporal decrease in volume complemented the expansion of the pore space. Nevertheless, the volume fractions determined by the image analysis essentially differed from the physical composition of specimens and were several times less sensitive to curing. Because of the extremely heterogenous microstructure and the abundance of calcium, the mastic phase had the highest attenuation of X-rays, but the attenuations of bitumen- and cement-dominated systems experienced contrary temporal trends. The sand and pore space had typically smooth and oppositely evolving axial distributions with the highest-density plateau in the middle, while the mastic was distributed uniformly. The radial distributions evolved less irregularly and notably interfered with the post-processing of beam hardening. The temporal increase in the pore space's local thicknesses was extremely unevenly distributed across diameters. Except the sand particle size distributions, all results were almost excellently repeatable. Finally, the interaction with X-rays was identified as crucial for the interpretation and validity of the results. Moreover, although water could not be segmented using the conventional X-ray tomography, its discrete signature was present throughout the behaviour of other phases. [ABSTRACT FROM AUTHOR] more...
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- 2024
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4. Comparative Analysis of Internal Porosity in AM Ti64 Using X-Ray Computed Tomography and Mechanical Polishing Serial Sectioning
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Bryce Jolley, Christine Knott, Daniel Sparkman, and Michael Uchic
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Additive manufacturing (AM) ,internal porosity ,nondestructive evaluation ,serial sectioning ,X-ray computed tomography (XCT) ,Instruments and machines ,QA71-90 ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
X-ray computed tomography (XCT) is a widely adopted nondestructive technique for characterizing internal porosity in additive manufactured (AM) components. However, the accuracy and precision of porosity characterization using XCT can be affected by factors, such as XCT system configuration and post-processing methodologies. This study investigates the influence of these variables on porosity characterization by comparing results obtained from four different XCT systems and two distinct analysis workflows applied to a single metallic AM sample. A benchmark is also established for the XCT performance by using a high-resolution reference dataset generated through mechanical polishing serial sectioning (MPSS). Porosity metrics, including volume fraction, pore count, size distribution, and equivalent spherical diameter (ESD), were computed for large pores ( $\ge 84~\mu $ m) within the XCT and MPSS datasets. By comparing these metrics across XCT systems and workflows, this research aims to demonstrate the variability introduced by different XCT configurations and analysis procedures, providing insights into the potential limitations and uncertainty considerations needed while carrying out XCT-based porosity characterization of AM components. more...
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- 2024
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5. Full-Field Strain Measurements of the Muscle-Tendon Junction Using X-ray Computed Tomography and Digital Volume Correlation.
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Iwasaki, Nodoka, Karali, Aikaterina, Roldo, Marta, and Blunn, Gordon
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COMPUTED tomography , *SHEAR strain , *SKELETAL muscle , *PHOSPHOTUNGSTIC acids , *PHYSICAL activity - Abstract
We report, for the first time, the full-field 3D strain distribution of the muscle-tendon junction (MTJ). Understanding the strain distribution at the junction is crucial for the treatment of injuries and to predict tear formation at this location. Three-dimensional full-field strain distribution of mouse MTJ was measured using X-ray computer tomography (XCT) combined with digital volume correlation (DVC) with the aim of understanding the mechanical behavior of the junction under tensile loading. The interface between the Achilles tendon and the gastrocnemius muscle was harvested from adult mice and stained using 1% phosphotungstic acid in 70% ethanol. In situ XCT combined with DVC was used to image and compute strain distribution at the MTJ under a tensile load (2.4 N). High strain measuring 120,000 µε, 160,000 µε, and 120,000 µε for the first principal stain (εp1), shear strain (γ), and von Mises strain (εVM), respectively, was measured at the MTJ and these values reduced into the body of the muscle or into the tendon. Strain is concentrated at the MTJ, which is at risk of being damaged in activities associated with excessive physical activity. [ABSTRACT FROM AUTHOR] more...
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- 2024
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6. Quality Control for Additive Manufacturing
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Al-Meslemi, Yahya, Ferreira, Kevin, Mehdi-Souzani, Charyar, Obaton, Anne-Françoise, Nouira, Hichem, Anwer, Nabil, Merkle, Dieter, Managing Editor, Pei, Eujin, editor, Bernard, Alain, editor, Gu, Dongdong, editor, Klahn, Christoph, editor, Monzón, Mario, editor, Petersen, Maren, editor, and Sun, Tao, editor more...
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- 2023
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7. Mechanism Analysis on Carbonation of Hardened Cement Paste with XCT.
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Wang, Yaocheng, Chen, Fuzi, Li, Zhouyi, Yang, Wengen, Zhan, Baojian, Li, Dawang, Xing, Feng, and Li, Weiwen
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CARBONATION (Chemistry) , *COMPUTED tomography , *CEMENT , *PASTE , *MEASUREMENT errors - Abstract
X-ray computed tomography (XCT) was used to monitor microstructure changes of hardened cement paste, with different water/cement ratios during a one-dimensional carbonation process. After removing equipment-induced measurement errors by a volume-constant method, the pores, dense hydration products, loose hydration products, and unhydrated cement in the sample were classified. Consequently, variation of each component with depth and carbonation duration were obtained, based on which mechanism of carbonation on hardened cement paste was conducted. Results showed that microstructure changes in hardened cement paste under CO2 effects is a coexisting simultaneous densification and cracking process. Within the entire carbonation process, the changes exhibited a general alternate pattern of densification–cracking–redensification, leading to connection of micropores into macro ones in hardened cement paste (i.e., the so-called carbonation-induced cracking); entire volume of the pores bigger than 4.4 μm did not present obvious changes during carbonation; a CO2 influence depth can be obtained by this method, which has an approximate linear relationship with the square root of carbonation duration and has limited influence with the water/cement ratio used in this study. [ABSTRACT FROM AUTHOR] more...
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- 2023
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8. Open-porous magnesium-based scaffolds withstand in vitro corrosion under cyclic loading: A mechanistic study
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Roxane Bonithon, Colin Lupton, Marta Roldo, Joseph Nicholas Dunlop, Gordon William Blunn, Frank Witte, and Gianluca Tozzi
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Magnesium alloys ,Bone regeneration ,In vitro corrosion ,X-ray computed tomography (XCT) ,Digital volume correlation (DVC) ,Materials of engineering and construction. Mechanics of materials ,TA401-492 ,Biology (General) ,QH301-705.5 - Abstract
The successful application of magnesium (Mg) alloys as biodegradable bone substitutes for critical-sized defects may be comprised by their high degradation rate resulting in a loss of mechanical integrity. This study investigates the degradation pattern of an open-porous fluoride-coated Mg-based scaffold immersed in circulating Hanks' Balanced Salt Solution (HBSS) with and without in situ cyclic compression (30 N/1 Hz). The changes in morphological and mechanical properties have been studied by combining in situ high-resolution X-ray computed tomography mechanics and digital volume correlation. Although in situ cyclic compression induced acceleration of the corrosion rate, probably due to local disruption of the coating layer where fatigue microcracks were formed, no critical failures in the overall scaffold were observed, indicating that the mechanical integrity of the Mg scaffolds was preserved. Structural changes, due to the accumulation of corrosion debris between the scaffold fibres, resulted in a significant increase (p more...
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- 2023
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9. In Vivo Bone Progression in and around Lattice Implants Additively Manufactured with a New Titanium Alloy.
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Obaton, Anne-Françoise, Fain, Jacques, Meinel, Dietmar, Tsamos, Athanasios, Léonard, Fabien, Lécuelle, Benoît, and Djemaï, Madjid
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COMPUTED tomography ,TITANIUM alloys ,SURFACE finishing ,OSSEOINTEGRATION ,TISSUES - Abstract
The osseointegration in/around additively manufactured (AM) lattice structures of a new titanium alloy, Ti–19Nb–14Zr, was evaluated. Different lattices with increasingly high sidewalls gradually closing them were manufactured and implanted in sheep. After removal, the bone–interface implant (BII) and bone–implant contact (BIC) were studied from 3D X-ray computed tomography images. Measured BII of less than 10 µm and BIC of 95% are evidence of excellent osseointegration. Since AM naturally leads to a high-roughness surface finish, the wettability of the implant is increased. The new alloy possesses an increased affinity to the bone. The lattice provides crevices in which the biological tissue can jump in and cling. The combination of these factors is pushing ossification beyond its natural limits. Therefore, the quality and speed of the ossification and osseointegration in/around these Ti–19Nb–14Zr laterally closed lattice implants open the possibility of bone spline key of prostheses. This enables the stabilization of the implant into the bone while keeping the possibility of punctual hooks allowing the implant to be removed more easily if required. Thus, this new titanium alloy and such laterally closed lattice structures are appropriate candidates to be implemented in a new generation of implants. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
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10. Machine learning augmented X-ray computed tomography features for volumetric defect classification in laser beam powder bed fusion.
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Ye, Jiafeng, Poudel, Arun, Liu, Jia, Vinel, Aleksandr, Silva, Daniel, Shao, Shuai, and Shamsaei, Nima
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COMPUTED tomography , *MACHINE learning , *LASER beams , *K-nearest neighbor classification - Abstract
This study proposes a data-driven framework to augment low-resolution X-ray computed tomography (LR-XCT) scanning with machine learning (ML) for efficient defect inspection and classification for laser beam powder bed fusion (L-PBF) process. The framework leverages the efficiency of LR-XCT scanning and improves defect classification accuracy with data-driven augmentation. Since volumetric defects can severely influence the usability and durability of L-PBF parts, it is critical to accurately classify defect types (i.e., keyhole, lack of fusion, and gas-entrapped pore) and understand their fabrication conditions and their impacts on the part performance. Additionally, it is reported that each type of defects has distinct morphological features, which can be creatively used for defect classification. In the proposed framework, the distinct morphological features of different types of defects are extracted from the LR-XCT, and they are augmented based on their relationships with the morphological features from high-resolution XCT (HR-XCT) scans. These augmented LR-XCT morphological features are used in ML-based defect classifiers, among which the k-nearest neighbor classifier has achieved the highest defect classification accuracy of 90.6%, with an improvement of 7.7% over directly using the LR-XCT morphological features. Moreover, defect classification with augmented LR-XCT morphological features saves up to 75% of the scanning time compared to HR-XCT scanning. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
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11. Visualization of Macroscopic Structure of Ultra-high Performance Concrete Based on X-ray Computed Tomography Using Immersive Environments
- Author
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Khadka, Rajiv, Acharya, Mahesh, LaBrier, Daniel, Mashal, Mustafa, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Chen, Jessie Y. C., editor, and Fragomeni, Gino, editor more...
- Published
- 2022
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12. Internal and interfacial microstructure characterization of ice droplets on surfaces by X-ray computed tomography.
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Snels, Laurens, Mostofi Sarkari, Navid, Soete, Jeroen, Maes, Arne, Antonini, Carlo, Wevers, Martine, Maitra, Tanmoy, and Seveno, David
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COMPUTED tomography , *HYDROPHOBIC surfaces , *CONTACT angle , *SURFACE analysis , *MICROSTRUCTURE - Abstract
[Display omitted] Characterizing the microstructure of an ice/surface interface and its effect on the icephobic behavior of surfaces remains a significant challenge. Introducing X-ray Computed Tomography (XCT) can provide unprecedented insights into the internal (porosity) and interfacial structures, i.e. wetting regime, between (super)hydrophobic surfaces and ice by visualizing these optically inaccessible regions. Frozen droplets with controlled volume were deposited on top of metallic and polymeric substrates with different levels of wettability. Different modes of XCT (3D and 4D) were utilized to obtain information on the internal and interfacial structure of the ice/surface system. The results were supplemented by conventional surface analysis techniques, including optical profilometry and contact angle measurements. Using XCT on ice/surface systems, the 3D and 4D (imaging with temporal resolution) structural information can be visualized. From these datasets, qualitative and quantitative results were obtained, not only for characterizing the interface but also for analyzing the entire droplet/surface system, e.g., measurement of porosity size, shape, and location. These results highlight the potential of XCT in the characterization of both droplets and substrates and proves that the technique can aid to develop hydrophobic surfaces for use as icephobic materials. [ABSTRACT FROM AUTHOR] more...
- Published
- 2023
- Full Text
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13. One thousand soils for molecular understanding of belowground carbon cycling.
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Bowman, Maggie M., Heath, Alexis E., Varga, Tamas, Battu, Anil K., Chu, Rosalie K., Toyoda, Jason, Cheeke, Tanya E., Porter, Stephanie S., Moffett, Kevan B., LeTendre, Brittany, Qafoku, Odeta, Bargar, John R., Mans, Douglas M., Hess, Nancy J., and Graham, Emily B. more...
- Abstract
While significant progress has been made in understanding global carbon (C) cycling, the mechanisms regulating belowground C fluxes and storage are still uncertain. New molecular technologies have the power to elucidate these processes, yet we have no widespread standardized implementation of molecular techniques. To address this gap, we introduce the Molecular Observation Network (MONet), a decadal vision from the Environmental Molecular Sciences Laboratory (EMSL), to develop a national network for understanding the molecular composition, physical structure, and hydraulic and biological properties of soil and water. These data are essential for advancing the next generation of multiscale Earth systems models. In this paper, we discuss the 1000 Soils Pilot for MONet, including a description of standardized sampling materials and protocols and a use case to highlight the utility of molecular-level and microstructural measurements for assessing the impacts of wildfire on soil. While the 1000 Soils Pilot generated a plethora of data, we focus on assessments of soil organic matter (SOM) chemistry via Fouriertransform ion cyclotron resonance-mass spectrometry and microstructural properties via X-ray computed tomography to highlight the effects of recent fire history in forested ecosystems on belowground C cycling. We observed decreases in soil respiration, microbial biomass, and potential enzyme activity in soils with high frequency burns. Additionally, the nominal oxidation state of carbon in SOM increased with burn frequency in surface soils. This results in a quantifiable shift in the molecular signature of SOM and shows that wildfire may result in oxidation of SOM and structural changes to soil pore networks that persist into deeper soils. [ABSTRACT FROM AUTHOR] more...
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- 2023
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14. Applications of X-ray computed tomography in textile field
- Author
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GUO Weina, GAO Yantao, HU Wenfeng, and WU Xiangji
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x-ray computed tomography (xct) ,structure characterization ,textile ,applications ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 - Abstract
Traditional optical imaging technique used as an analysis method for microstructure can only observe surface and can't achieve 3D characterization of the material interior, which greatly limits its application in textile field. In order to promote the application and development of 3D CT in textile field,a description of the test equipment, test methods, influencing factors of image quality of X-ray computed tomography (XCT) in textile application were introduced. Further, the applications of XCT technology in the characterization of internal structure of fabrics, aided modelling to predict fabric properties (heat transmitting, compressibility) and yarn research were reviewed. Finally, the advantages and disadvantages of XCT technology in textile applications were summarized, while the potential applications of XCT technology in future were prospected in view of lack of research in the textile field based on XCT. more...
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- 2022
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15. One thousand soils for molecular understanding of belowground carbon cycling
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Maggie M. Bowman, Alexis E. Heath, Tamas Varga, Anil K. Battu, Rosalie K. Chu, Jason Toyoda, Tanya E. Cheeke, Stephanie S. Porter, Kevan B. Moffett, Brittany LeTendre, Odeta Qafoku, John R. Bargar, Douglas M. Mans, Nancy J. Hess, and Emily B. Graham more...
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soil organic matter ,X-ray computed tomography (XCT) ,Fourier transform ion cyclotron resonance mass spectrometry ,FTICR-MS ,open science ,molecular observation network (MONet) ,Chemistry ,QD1-999 ,Engineering geology. Rock mechanics. Soil mechanics. Underground construction ,TA703-712 - Abstract
While significant progress has been made in understanding global carbon (C) cycling, the mechanisms regulating belowground C fluxes and storage are still uncertain. New molecular technologies have the power to elucidate these processes, yet we have no widespread standardized implementation of molecular techniques. To address this gap, we introduce the Molecular Observation Network (MONet), a decadal vision from the Environmental Molecular Sciences Laboratory (EMSL), to develop a national network for understanding the molecular composition, physical structure, and hydraulic and biological properties of soil and water. These data are essential for advancing the next generation of multiscale Earth systems models. In this paper, we discuss the 1000 Soils Pilot for MONet, including a description of standardized sampling materials and protocols and a use case to highlight the utility of molecular-level and microstructural measurements for assessing the impacts of wildfire on soil. While the 1000 Soils Pilot generated a plethora of data, we focus on assessments of soil organic matter (SOM) chemistry via Fourier-transform ion cyclotron resonance-mass spectrometry and microstructural properties via X-ray computed tomography to highlight the effects of recent fire history in forested ecosystems on belowground C cycling. We observed decreases in soil respiration, microbial biomass, and potential enzyme activity in soils with high frequency burns. Additionally, the nominal oxidation state of carbon in SOM increased with burn frequency in surface soils. This results in a quantifiable shift in the molecular signature of SOM and shows that wildfire may result in oxidation of SOM and structural changes to soil pore networks that persist into deeper soils. more...
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- 2023
- Full Text
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16. Assessment of Additive Manufacturing Surfaces Using X-ray Computed Tomography.
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Sen, Cagdas, Dursun, Gokhan, Orhangul, Akin, and Akbulut, Guray
- Abstract
Surface characterization becomes an important practice in industry as the nature of metal additive manufacturing (AM) process offers varying resultant surfaces based on different process parameters and geometries. Integrating of X-ray computed tomography (XCT) technology into the characterization of AM surfaces by solving its' challenges will be a significant leap, especially for internal surfaces. In this paper, data of various AM surfaces obtained using a coherence scanning interferometry is compared with surfaces extracted from XCT measurements. Effects of specimen material and surface characteristics on evaluating different areal surface parameters using XCT are discussed. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
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17. Cracking during pyrolysis of preceramic polymers within glass microtubes.
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Larson, Natalie M., Summers, William D., and Zok, Frank W.
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COMPUTED tomography , *PYROLYSIS , *UNIFORM spaces , *FRACTURE mechanics , *POLYMERS - Abstract
Cracking of preceramic polymers during pyrolysis under highly‐constrained conditions is examined by X‐ray computed tomography of fine glass microtubes containing the pyrolyzing material. The microtubes represent model geometries that mimic the long channels between fibers during production of ceramic composites by precursor impregnation and pyrolysis. Complementary fracture mechanics analyses of interface cracking and crack kinking are used to glean insights into the conditions under which periodic alternating cracks form. A key finding is that alternating cracks are an inherent feature of constrained pyrolysis. This feature is attributable in large part to the high energy release rates for interface cracks to kink into the pyrolyzing material under the hydrostatic tension developed during pyrolysis. It also requires interfaces with toughness comparable to that of the pyrolyzing material, to prevent large‐scale interface separation. The results further indicate the need for small uniform spaces for pyrolysis within fiber preforms in order to produce networks of fine periodic pyrolysis cracks; these networks in turn facilitate impregnation and pyrolysis in subsequent processing cycles. [ABSTRACT FROM AUTHOR] more...
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- 2022
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18. Quantifying the Effects of Grain Refiners Al-Ti-B and La on the Microstructure and Mechanical Properties of W319 Alloy.
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Liu, Xinxiu, Wang, Bing, Li, Quan, Wang, Junsheng, Zhang, Chi, Xue, Chengpeng, Yang, Xinghai, Tian, Guangyuan, Liu, Xiaoguang, and Tang, Hongqun
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RARE earth metals ,HYPEREUTECTIC alloys ,MICROSTRUCTURE ,HEAT treatment ,ALLOYS ,ALUMINUM alloys ,ALUMINUM recycling ,MICROPOROSITY - Abstract
It is well known that the microstructure distribution in recycled Al-Si alloys has a large impact on the final mechanical properties. In this study, the microstructure, including Fe-rich intermetallics and microporosity, was quantitatively adjusted using multi-scale characterization with microalloying rare earth elements and traditional grain refiners as the objects of study. It was found that the addition of Al-Ti-B to W319 recycled aluminum alloy reduces the microstructure size and Fe-rich intermetallics, while the addition of La facilitates the transformation of harmful β-Fe into less harmful particles and the densification of coarse eutectic Si, promoting the refining effects on the microstructure additionally. Therefore, the RE and Al-Ti-B master alloy could be a potential new grain refining agent, especially for Al-cast alloys when the ductility is critical for designing. The improvement in elongation far exceeds the original level, up to 69.6%, while maintaining the same level of strength or even better. At the same time, the excessive addition of La may lead to the depletion of Cu and Ti elements during heat treatment, degrading ductility and strength. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
- Full Text
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19. Full‐field strain of regenerated bone tissue in a femoral fracture model.
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KARALI, A., KAO, A. P., MEESON, R., ROLDO, M., BLUNN, G. W., and TOZZI, G.
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FEMORAL fractures , *COMPUTED tomography , *REGENERATION (Biology) , *FEMUR , *FRACTURE healing , *BONE shafts - Abstract
Summary: The mechanical behaviour of regenerated bone tissue during fracture healing is key in determining its ability to withstand physiological loads. However, the strain distribution in the newly formed tissue and how this influences the way a fracture heals it is still unclear. X‐ray Computed Tomography (XCT) has been extensively used to assess the progress of mineralised tissues in regeneration and when combined with in situ mechanics and digital volume correlation (DVC) has been proven a powerful tool to understand the mechanical behaviour and full‐field three‐dimensional (3D) strain distribution in bone. The purpose of this study is therefore to use in situ XCT mechanics and DVC to investigate the strain distribution and load‐bearing capacity in a regenerating fracture in the diaphyseal bone, using a rodent femoral fracture model stabilised by external fixation. Rat femurs with 1 mm and 2 mm osteotomy gaps were tested under in situ XCT step‐wise compression in the apparent elastic region. High strain was present in the newly formed bone (εp1 and εp3 reaching 29 000 µε and –43 000 µε, respectively), with a wide variation and inhomogeneity of the 3D strain distribution in the regenerating tissues of the fracture gap, which is directly related to the presence of unmineralised tissue observed in histological images. The outcomes of this study will contribute in understanding natural regenerative ability of bone and its mechanical behaviour under loading. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
- Full Text
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20. Calibrated X-ray computed tomography for testing micro-scale pore defect in metallic powder particles for additive manufacturing
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Shihua Wang and Baoxi Xu
- Subjects
X-ray computed tomography (XCT) ,Non-destructive testing (NDT) ,Pore volume ,Porosity ,Metallic powder ,Electric apparatus and materials. Electric circuits. Electric networks ,TK452-454.4 - Abstract
In this paper, a non-destructive X-ray computed tomography (XCT) was introduced to measure hidden pore defects inside metallic powder used in additive manufacturing. The internally hidden pores were found to have sizes ranging from 10 μm to 30 μm within those powder particles (size: up to 100 μm). Corresponding porosity in four (4) different metallic powders were determined to be about 0.11% for Inconel 718, 0.02% for virgin Inconel 625, 0.31% for Recycled Inconel 625 and 0.03% for Stainless steel 316 powder materials. It demonstrated that the proposed XCT is applicable to determine the porosity of the powder particles. more...
- Published
- 2021
- Full Text
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21. X-Ray Tomographic Study of Pore Volume Fraction in Samples of Polymer Composite Materials. Scanning and Reconstruction of Tomographic Data.
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Demidov, A. A., Krupnina, O. A., Mikhailova, N. A., and Kosarina, E. I.
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COMPOSITE materials , *IMAGE reconstruction , *X-rays , *POLYMERS , *COMPUTED tomography - Abstract
A description of the X-ray tomographic studies of samples made of polymer composite materials for the purpose of quantitative determination of the pore volume fraction is presented. The tomographic examination includes two stages: scanning and image reconstruction. A subpixel scanning method was applied at the first stage to increase the image resolution. The corrections provided in the software of the tomograph were applied when reconstructing the image. The results of evaluating the volume fraction of pores obtained by subpixel and cylindrical scanning showed their complete convergence. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
- Full Text
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22. A multi-technique tomography-based approach for non-invasive characterization of additive manufacturing components in view of vacuum/UHV applications: preliminary results.
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Grazzi, Francesco, Cialdai, Carlo, Manetti, Marco, Massi, Mirko, Morigi, Maria Pia, Bettuzzi, Matteo, Brancaccio, Rosa, Albertin, Fauzia, Shinohara, Takenao, Kai, Tetsuya, Fedrigo, Anna, Di Giovanni, Adriano, Arneodo, Francesco, Torres, Rodrigo, Al-Ketan, Oraib, Elhashemi, Jumaanah, Taccetti, Francesco, and Giuntini, Lorenzo more...
- Abstract
In this paper, we have studied an additively manufactured metallic component, intended for ultra-high vacuum application, the exit-snout of the MACHINA transportable proton accelerator beam-line. Metal additive manufacturing components can exhibit heterogeneous and anisotropic microstructures. Two non-destructive imaging techniques, X-ray computed tomography and Neutron Tomography, were employed to examine its microstructure. They unveiled the presence of porosity and channels, the size and composition of grains and intergranular precipitates, and the general behavior of the spatial distribution of the solidification lines. While X-ray computed tomography evidenced qualitative details about the surface roughness and internal defects, neutron tomography showed excellent ability in imaging the spatial density distribution within the component. The anisotropy of the density was attributed to the material building orientation during the 3D printing process. Density variations suggest the possibility of defect pathways, which could affect high vacuum performances. In addition, these results highlight the importance of considering building orientation in the design for additive manufacturing for UHV applications. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
- Full Text
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23. The mechanistic origins of heterogeneous void growth during ductile failure.
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Vaughan, M.W., Lim, H., Pham, B., Seede, R., Polonsky, A.T., Johnson, K.L., and Noell, P.J.
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HYDROSTATIC stress , *COMPUTED tomography , *DISLOCATION density , *CRYSTAL texture , *TOMOGRAPHY , *GRAIN - Abstract
In 1969, Rice and Tracey proposed that the rate of void growth during ductile failure is a strong function of the hydrostatic stress state. Numerous in-situ x-ray computed tomography (XCT) studies demonstrated that the average rate of void growth is well-predicted by modified versions of the Rice-Tracey equation. However, recent in-situ XCT studies of void growth demonstrated that individual voids grow in highly heterogeneous manners in a way that is not predicted by Rice-Tracey or similar models. Model-based studies using crystal plasticity finite element (CP-FE) suggest that local effects of grain orientation play a strong role during void growth, but we lack experimental data to test this hypothesis. The present study leverages recent advances in laboratory-based diffraction contrast tomography (Lab-DCT) and in-situ XCT to systematically examine the effects of grain orientation on void growth experimentally in an Al-2219 alloy. CP-FE modeling was used to assess the local stress states associated with voids and their influence on void growth rates. These data indicate that void growth is not simply controlled by the local hydrostatic stress or stress triaxiality. Additionally, no clear relationship between void growth rates and grain orientation were observed. Instead, void growth rates were highly stochastic in ways that could not be directly linked to the local stress or strain states. The combination of experimental and modeling data suggests that our current assumptions regarding the mechanisms of void growth are flawed and that additional factors, which may include the local dislocation density, affect the rate of void growth. [Display omitted] [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
24. Accelerating the dissolution and transformation of detrimental Fe-rich intermetallics in recycled Al-Mg-Si alloy by homogenization and hot deformation.
- Author
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Li, Quan, Wang, Junsheng, Liu, Xinxiu, Xue, Chengpeng, Wang, Shuo, Yang, Xinghai, Tian, Guangyuan, Su, Hui, Wu, Xuelong, and Miao, Yisheng
- Subjects
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IRON-manganese alloys , *COMPUTED tomography , *ALLOYS , *MICROPOROSITY - Abstract
The plate-like Fe-rich intermetallics in recycled Al-Mg-Si alloys dramatically degrade the mechanical properties, which has to be minimized to obtain the high-performance components. Previous finding of using Mn to neutralize the harmful Fe have proven to be effective at a Mn:Fe ratio of 2:1 in order to convert detrimental β-Al 5 FeSi (β-Fe) plates into less harmful α-Al₁₅(Fe, Mn)₃Si₂ (α-Fe) scripts. However, excess amount of Mn will inevitably introduce large fraction of intermetallic particles which reduce the ductility of alloy. In this study, we propose a new process which utilize both homogenization and hot deformation processes to achieve dissolution and transformation of detrimental Fe-rich intermetallics. The transformation mechanisms with limited Mn addition (Mn:Fe Ratio≈1) have been uncovered. After homogenization for 10 h, the percentage of β-Fe decreases from 1.13% to 0.87%. After 30% hot deformation, it further decreases to 0.45% and the elongation is increased by 55.97%. If we combine the hot deformation 30% with cold deformation by 20%, it will eventually decrease to 0.25%, achieving complete conversion from β-Fe to α-Fe, and the tensile strength is increased by 42.15%. To uncover the transformation mechanisms of Fe-rich intermetallics, 3D distribution of Fe-rich intermetallics and microporosity have been quantified as a function of processing conditions by using X-ray computed tomography (XCT), demonstrating that the new approach can make use of the Fe tolerable recycled Al alloys to achieve high strength and ductility. [Display omitted] • A new homogenization and hot deformation process to minimize detrimental Fe-rich intermetallics was found. • Phase transformation path from β-Fe to α-Fe with untraditional Mn:Fe Ratio ≈ 1 was uncovered. • 3D distribution of Fe-rich intermetallics and microporosity was quantified using X-ray CT. • Mechanism of β-Fe transformation was discovered by first-principles calculations. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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25. Multi-scale mechanical and morphological characterisation of sintered porous magnesium-based scaffolds for bone regeneration in critical-sized defects.
- Author
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Bonithon, Roxane, Kao, Alexander Peter, Fernández, Marta Peña, Dunlop, Joseph Nicholas, Blunn, Gordon William, Witte, Frank, and Tozzi, Gianluca
- Subjects
BONE regeneration ,BIODEGRADABLE materials ,COMPUTED tomography ,CANCELLOUS bone ,BIOACTIVE glasses ,MAGNESIUM ,BIOABSORBABLE implants ,YIELD stress - Abstract
Magnesium (Mg) and its alloys are very promising degradable, osteoconductive and osteopromotive materials to be used as regenerative treatment for critical-sized bone defects. Under load-bearing conditions, Mg alloys must display sufficient morphological and mechanical resemblance to the native bone they are meant to replace to provide adequate support and enable initial bone bridging. In this study, unique highly open-porous Mg-based scaffolds were mechanically and morphologically characterised at different scales. In situ X-ray computed tomography (XCT) mechanics, digital volume correlation (DVC), electron microscopy and nanoindentation were combined to assess the influence of material properties on the apparent (macro) mechanics of the scaffold. The results showed that Mg exhibited a higher connected structure (38.4mm
−3 and 6.2mm−3 for Mg and trabecular bone (Tb), respectively) and smaller spacing (245µm and 629µm for Mg and Tb, respectively) while keeping an overall appropriate porosity of 55% in the range of trabecular bone (30-80%). This fully connected and highly porous structure promoted lower local strain compared to the trabecular bone structure at material level (i.e. -22067 ± 8409µε and -40120 ± 18364µε at 6% compression for Mg and trabecular bone, respectively) and highly ductile mechanical behaviour at apparent level preventing premature scaffold failure. Furthermore, the Mg scaffolds exceeded the physiological strain of bone tissue generated in daily activities such as walking or running (500-2000µε) by one order of magnitude. The yield stress was also found to be close to trabecular bone (2.06MPa and 6.67MPa for Mg and Tb, respectively). Based on this evidence, the study highlights the overall biomechanical suitability of an innovative Mg-based scaffold design to be used as a treatment for bone critical-sized defects. Bone regeneration remains a challenging field of research where different materials and solutions are investigated. Among the variety of treatments, biodegradable magnesium-based implants represent a very promising possibility. The novelty of this study is based on the characterisation of innovative magnesium-based implants whose structure and manufacturing have been optimised to enable the preservation of mechanical integrity and resemble bone microarchitecture. It is also based on a multi-scale approach by coupling high-resolution X-ray computed tomography (XCT), with in situ mechanics, digital volume correlation (DVC) as well as nano-indentation and electron-based microscopy imaging to define how degradable porous Mg-based implants fulfil morphological and mechanical requirements to be used as critical bone defects regeneration treatment. [Display omitted] [ABSTRACT FROM AUTHOR] more...- Published
- 2021
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26. Microstructure and Mechanical Properties of Ti–Ta Composites Prepared Through Cold Spray Additive Manufacturing
- Author
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Tang, Junrong, Tariq, Naeem ul Haq, Zhao, Zhipo, Guo, Mingxiao, Liu, Hanhui, Ren, Yupeng, Cui, Xinyu, Shen, Yanfang, Wang, Jiqiang, and Xiong, Tianying
- Published
- 2022
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27. Quantifying the Effects of Grain Refiners Al-Ti-B and La on the Microstructure and Mechanical Properties of W319 Alloy
- Author
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Xinxiu Liu, Bing Wang, Quan Li, Junsheng Wang, Chi Zhang, Chengpeng Xue, Xinghai Yang, Guangyuan Tian, Xiaoguang Liu, and Hongqun Tang
- Subjects
aluminum alloy ,Al-Ti-B ,La ,microporosity ,X-ray computed tomography (XCT) ,U-net CNN ,Mining engineering. Metallurgy ,TN1-997 - Abstract
It is well known that the microstructure distribution in recycled Al-Si alloys has a large impact on the final mechanical properties. In this study, the microstructure, including Fe-rich intermetallics and microporosity, was quantitatively adjusted using multi-scale characterization with microalloying rare earth elements and traditional grain refiners as the objects of study. It was found that the addition of Al-Ti-B to W319 recycled aluminum alloy reduces the microstructure size and Fe-rich intermetallics, while the addition of La facilitates the transformation of harmful β-Fe into less harmful particles and the densification of coarse eutectic Si, promoting the refining effects on the microstructure additionally. Therefore, the RE and Al-Ti-B master alloy could be a potential new grain refining agent, especially for Al-cast alloys when the ductility is critical for designing. The improvement in elongation far exceeds the original level, up to 69.6%, while maintaining the same level of strength or even better. At the same time, the excessive addition of La may lead to the depletion of Cu and Ti elements during heat treatment, degrading ductility and strength. more...
- Published
- 2022
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28. On the Breakage of High Aspect Ratio Crystals in Filter Beds under Continuous Percolation.
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Mahdi, F. M., Shier, A. P., Fragkopoulos, I. S., Carr, J., Gajjar, P., and Muller, F. L.
- Subjects
- *
CRYSTAL filters , *COMPUTED tomography , *PERCOLATION , *BEDS , *GLUTAMIC acid - Abstract
Purpose: This work details experimental observations on the effect of liquid flow percolating through packed beds of crystals to elucidate how the filtration pressure severely alters the size distribution and crystal shape. Pressure filtration is widely used in the pharmaceutical industry, and frequently results in undesired size distribution changes that hinder further processing. Methods: The percolation methodology presented fixes fluid flow through a bed of crystals, resulting in a pressure over the bed. X-ray computed tomography (XCT) provided detailed observations of the bed structure. Detailed 2D particle size data was obtained using automated microscopy and was analysed using an in-house developed tool. Results: Crystal breakage is observed when the applied pressure exceeds a critical pressure: 0.5–1 bar for ibuprofen, 1–2 bar for β-L glutamic acid (LGA) and 2–2.5 bar for para amino benzoic acid (PABA). X-ray computed tomography showed significant changes in bed density under the applied pressure. Size analysis and microscope observations showed two modes of breakage: (i) snapping of long crystals and (ii) shattering of crystals. Conclusion: LGA and PABA have a similar breakage strength (50 MPa), ibuprofen is significantly weaker (9 MPa). Available breakage strength data may be correlated to the volumetric Gibbs free energy. Data from 12 and 35 mm bed diameters compares well to literature data in a 80 mm filter; the smaller, easy to operate percolation unit is a versatile tool to assess crystal breakage in filtration operations. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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29. Benefits of applying X-ray computed tomography in bentonite based material research focussed on geological disposal of radioactive waste.
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Reijonen, Heini Maria, Kuva, Jukka, and Heikkilä, Pasi
- Subjects
COMPUTED tomography ,RADIOACTIVE waste disposal ,SEALING compounds ,GEOLOGICAL repositories ,GEOLOGICAL research ,BENTONITE - Abstract
Bentonite-based geomaterials are included in the designs of geological repository planning in most countries, especially in high-level radioactive waste disposal. Physical integrity of the bentonite sealant is key in assuring its hydraulic and retention properties, which affect the long-term performance of the repositories. Examination of the internal textures and structures of bentonite has been challenging until recently. Here, X-ray computed tomography (XCT) is applied to improve the textural and structural characterization of natural and man-made bentonite samples. Based on these initial analyses, clear benefits have been identified compared with conventional bentonite research methods. First, applying XCT prior to destructive analytical methods provides means to distinguish secondary features or in situ textures. It allows to eliminate false interpretations due to sample deformation and guides subsampling. Second, XCT images add the third dimension to analyses, allowing larger spatial coverage in less time. Overall, findings support the application of XCT for reducing uncertainties related to physical characterization of bentonite samples, both natural and industrial. They also show that XCT has potential to be developed to support quality assurance processes for bentonite sealant manufacturing. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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30. Exploring the fabrication limits of thin-wall structures in a laser powder bed fusion process.
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Wu, Ziheng, Narra, Sneha Prabha, and Rollett, Anthony
- Subjects
- *
SYNCHROTRONS , *POWDERS , *HEAT exchangers , *SURFACE finishing , *COMPUTED tomography , *LASERS , *RESIDUAL stresses - Abstract
Although additive manufacturing (AM) is becoming increasingly popular for various applications, few studies have addressed design and potential problems in thin wall fabrication for the laser powder bed fusion (LPBF) process. In the LPBF process, rapid cooling induces thermal shrinkage, which in turn, results in high residual stress and complicates thin wall fabrication. The minimum wall thickness is limited by the parameters and machine settings while the dimensional accuracy is controlled by the powder size, scan strategy, and part geometry. The ability to fabricate thin-wall components is important for applications such as heat exchangers (HX). This study explores the performance of the LPBF process by fabricating thin walls with extreme geometries in different processing conditions and alloys using an EOS M290 LPBF machine. Results show that the material, part design, and scanning strategy contribute to the variation in thin wall dimensions. A maximum inclination angle of 60° and a minimum wall thickness of ~ 100 μm in Ti-6Al-4V, Inconel 718, and AlSi10Mg were achieved using optimized part design and processing conditions. The effects of part design and material on the thermal distortion and surface finish of thin walls were also investigated leading to a discussion on how the scan mode assigned by the EOS software affects design and fabrication. Additionally, synchrotron-based X-ray micro-tomography (μSXCT) was utilized to quantify the porosity in thin-wall structures and to correlate it with the integrity of the structures. Comprehensive design guidelines presented in this work can increase the success rate of fabricating thin-wall geometries. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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31. X-ray computed tomography to investigate industrial cast Al-alloys.
- Author
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Bandara, Ajith, Kan, Koichi, Morii, Hisashi, Koike, Akifumi, and Aoki, Toru
- Abstract
This paper describes the use of X-ray computed tomography (XCT) to inspect the internal defects of industrial Aluminum alloys die-casting, to justify the adequateness of super sealant resins in filling tiny holes, and to reduce the casting porosity of metals by the impregnation process. High-resolution 2D slice images were generated by a microfocus X-ray CT system with direct conversion Cadmium Telluride (CdTe) flat panel detector (FPD). Moreover, we were able to visualize the internal defects of the two different shapes of casting objects. The gray-value contrasts of the CT images were excellent to distinguish the resin material in the alloy samples after impregnation treatment. Furthermore, to determine the dimensions of internal defects, virtual sectioning was carried out to view the cross-section of the metal samples and dimensions of internal defects. Dual-energy X-ray computed tomography (DXCT) was used with an energy differentiation type 64-pixel linear array photon-counting line sensor for the material characterization. The impregnated resin part inside the castings defects was verified based on the effective atomic number with a 2.92% low error margin. Hence, this will be a useful qualitative and quantitative advancement to rapid and detailed non-destructive analysis within the die-casting industries in improving the quality of the impregnation process. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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32. Multi-scale Cu-Cr composites using elemental powder blending in laser powder-bed fusion.
- Author
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Varoto, Lucas, Lhuissier, Pierre, Roure, Sophie, Papillon, Anthony, Chosson, Mélissa, Pauzon, Camille, Bataillon, Xavier, Fivel, Marc, Boller, Elodie, Lapouge, Pierre, Hébrard, Pierre, and Martin, Guilhem more...
- Subjects
- *
LASER fusion , *METALLIC composites , *X-ray computed microtomography , *POWDERS , *COMPUTED tomography , *SYNCHROTRONS - Abstract
Cu-Cr-based alloys are good candidates for thermo-electrical applications because of their excellent combination of mechanical, thermal, and electrical properties. However, tailoring their microstructure via traditional processes such as sintering and casting remains a challenging task. Herein, we introduce a strategy to fabricate multiscale Cu-25Cr composites. This is achieved through in-situ alloying from elemental powder blending in laser powder-bed fusion. The process is monitored layer-by-layer using synchrotron X-ray microtomography. We show that by changing the melt-pool size and its overlap, one can produce multiscale Cu-Cr composites with coarse (∼50 µm) and fine Cr-spheroids (<500 nm) while controlling their spatial distribution. Coarse Cr particles are preferentially located at the melt pool boundaries while fine spherical Cr particles are distributed in the melt pool interior. Spatial variations in mechanical properties are revealed using nanoindentation mapping. This strategy opens new opportunities to optimize multiscale metal matrix composite through the manipulation of the scanning strategy. This is special type of abstract that is so short and could be inserted after main abstract of article, as a blurb or inserted as annotations into a Table of contents [Display omitted] [ABSTRACT FROM AUTHOR] more...
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- 2024
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33. Microstructure analysis of quartz fiber reinforced SiO2 matrix composites by X-ray computed tomography.
- Author
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Li, Chenxiao, Xia, Tao, Gao, Shitao, Yan, Manling, Chen, Yurong, Wan, Binghong, Li, Junsheng, and Wan, Fan
- Subjects
- *
COMPUTED tomography , *QUARTZ analysis , *YARN , *FIBROUS composites , *QUARTZ , *MICROSTRUCTURE , *FIBERS , *SILICA gel - Abstract
This paper presents the microstructure of quartz fiber reinforced SiO 2 matrix (SiO 2f /SiO 2) wave-transparent composites characterized by X-ray computed tomography (XCT) and the impregnation of silica sol by conducting permeability and pore network model analyses. Results show that in 2.5D woven structural preform silica gel mainly flowed along the extension direction of weft yarns during impregnation, and the permeability rate in this direction reached 368.49μm2. Attributing to the large pore size, large throat radius and good pore connectivity, impregnation of this preform was more uniform, resulting in a small final porosity of the composite (2.32%). Comparatively speaking, in stitched structural preform silica sol flowed primarily between the layers of fiber cloths, achieving a maximum permeability rate of 36.47μm2, but along the direction of stitching fiber yarns permeability rate was only 5.23μm2. Small throat radius and pore size of fiber preform led to poor impregnation effect and a total porosity of 11.85%. Preform structure plays a crucial role in the densification process of SiO 2f /SiO 2 composites prepared by sol-gel method. • Morphology characteristics and phase distribution of two types of SiO 2f /SiO 2 composites were observed. • Permeability and pore characteristics of fiber preforms were discussed. • Preform structure plays a crucial role in the densification process of SiO 2f /SiO 2 composites prepared by sol-gel method. • XCT has significant advantages in exploring the microstructure and anisotropy of fiber-reinforced composites. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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34. Microstructure and mechanical properties of H13 steel block produced by wire arc additive manufacturing.
- Author
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Yang, Linpo, Lin, Jian, Zhu, Bingyue, Zhang, Yongqiang, Sun, Qisong, Fu, Hanguang, and Lei, Yongping
- Subjects
- *
MICROSTRUCTURE , *GRAIN , *STEEL , *TENSILE tests , *COMPUTED tomography , *TENSILE strength - Abstract
• The H13 steel block were prepared by wire arc additive manufacturing. • The microstructure was studied in detail. • The tensile strength and elongation were studied. • The internal information related to micropores is studied. • The reason of the low elongation of printing block is deduced. The H13 steel block was successfully prepared by cold metal transfer(CMT) wire-arc additive manufacturing(WAAM) method. The microstructure characteristics and mechanical properties of the printed block were both studied by experiments. It was found that there were obvious difference in the microstructure and mechanical properties between the central part and overlapping parts of the printed block. It was shown from the microstructure observation that the printed block was mainly composed of martensite and residual austenite. There was an obvious primary austenite grain boundary observed in the base phase. In addition, compared with the overlapping part, the content of residual austenite in the central part was lower. It was shown that the average value of the microhardness in the central part was 596HV, while it was 534HV for the overlapping part due to the higher content of residual austenite. Tensile tests were conducted for different direction of the printed block. Micropores with a volume of 100–400 μm3 were observed in the printed block, with 90 % of the micropores in the range of 100–200 μm3 in volume. The micropores were uniformly distributed in the sample. The presence of micropores leads to the low elongation and tensile strength. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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35. Improved XCT image automatic segmentation for quantitative characterization of the meso-morphological features in the damaged braided composite fabric.
- Author
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Zheng, Kehong, Cao, Xiaoqi, Jiang, Zheyang, Chen, Hao, Qiu, Bingjing, Lu, Wenpan, Wu, Chenglie, Pan, Zhongxiang, and Wu, Zhenyu
- Subjects
- *
IMAGE segmentation , *BRAIDED structures , *MECHANICAL behavior of materials , *AXIAL loads , *COMPOSITE materials , *COMPUTED tomography - Abstract
Accurately identifying various meso-morphological features and sub-phases within the damaged braided composite fabric is crucial for assessing the mechanical properties of composites under complex loading conditions and different processing parameters. However, obtaining 3D reconstructions that can be quantitatively analyzed is still a challenge, primarily due to the low contrast of the meso-morphological features (yarn tow and matrix crack networks). In this work, a new data enhancement algorithm is proposed to generate a realistic-looking artificial training dataset for enriching the information of the meso-morphological features. Then, the effect of various training networks and training parameters (the size of real and hybrid training dataset, number of epochs) on segmentation performance were examined. Finally, the meso-morphological features were statistically analyzed to accurately evaluate the mechanical properties of the composite material. The work presented here provides an effective tool that enables the quantitative analysis of the dynamic crack evolution process under the axial load of the composite materials. [Display omitted] [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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36. Effect of Surface Moisture Condition on Substrate-Repair Concrete Overlay Transition Zone
- Author
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Annand, Douglas Michael and Annand, Douglas Michael
- Abstract
Concrete is the most widely used construction material in the world. Given its relative availability, strength, economy, and versatility to fit various applications, the material has been incorporated in roadways, bridges, buildings, and a host of other infrastructure projects. Oftentimes, concrete will be exposed to several environmental conditions that ultimately affect its durability and lifespan. These conditions include repeated freezing and thawing, chloride intrusion, sulfate attack, alkali-silica reaction, and many others. Given the age and condition of American infrastructure, concrete structures throughout the country need repair or rehabilitation. Often this repair includes the removal of degraded or damaged concrete and the application of an overlay material. There are several factors affecting the bond performance of the newly formed substrate-repair concrete, such as surface roughness, overlay material, and substrate moisture condition. The work presented in this thesis is dedicated to understanding the effect of substrate moisture condition on the overlay transition zone (OTZ) of the substrate-repair concrete. The substrate moisture condition can significantly impact the microstructure characterization of the OTZ. If the substrate is too dry, then it may absorb water from the repair material, reducing the local water-to-cement (w/c) ratio in the OTZ. Conversely, if the substrate is too wet, then the w/c ratio of the OTZ will be locally increased. In both scenarios, the interfacial bond strength is expected to be modified due to the change in the local w/c ratio. To understand this effect, various test methods and degradation mechanisms were explored. Initially, substrate-repair concrete specimens were prepared utilizing three separate substrate moisture conditions: saturated surfaced dry (SSD), sub-saturated surface dry (Sub-SSD), and oven dry (OD). After allowing these samples to cure, the strength and ion penetration risk were evaluated. The bond st more...
- Published
- 2023
37. Internal and interfacial microstructure characterization of ice droplets on surfaces by X-ray computed tomography
- Author
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Snels, L, Mostofi Sarkari, N, Soete, J, Maes, A, Antonini, C, Wevers, M, Maitra, T, Seveno, D, Snels L., Mostofi Sarkari N., Soete J., Maes A., Antonini C., Wevers M., Maitra T., Seveno D., Snels, L, Mostofi Sarkari, N, Soete, J, Maes, A, Antonini, C, Wevers, M, Maitra, T, Seveno, D, Snels L., Mostofi Sarkari N., Soete J., Maes A., Antonini C., Wevers M., Maitra T., and Seveno D. more...
- Abstract
Hypothesis: Characterizing the microstructure of an ice/surface interface and its effect on the icephobic behavior of surfaces remains a significant challenge. Introducing X-ray Computed Tomography (XCT) can provide unprecedented insights into the internal (porosity) and interfacial structures, i.e. wetting regime, between (super)hydrophobic surfaces and ice by visualizing these optically inaccessible regions. Experiments: Frozen droplets with controlled volume were deposited on top of metallic and polymeric substrates with different levels of wettability. Different modes of XCT (3D and 4D) were utilized to obtain information on the internal and interfacial structure of the ice/surface system. The results were supplemented by conventional surface analysis techniques, including optical profilometry and contact angle measurements. Findings: Using XCT on ice/surface systems, the 3D and 4D (imaging with temporal resolution) structural information can be visualized. From these datasets, qualitative and quantitative results were obtained, not only for characterizing the interface but also for analyzing the entire droplet/surface system, e.g., measurement of porosity size, shape, and location. These results highlight the potential of XCT in the characterization of both droplets and substrates and proves that the technique can aid to develop hydrophobic surfaces for use as icephobic materials. more...
- Published
- 2023
38. In Vivo Bone Progression in and around Lattice Implants Additively Manufactured with a New Titanium Alloy
- Author
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Djemaï, Anne-Françoise Obaton, Jacques Fain, Dietmar Meinel, Athanasios Tsamos, Fabien Léonard, Benoît Lécuelle, and Madjid
- Subjects
osseointegration ,animal surgery ,implants ,lattices ,titanium alloy ,additive manufacturing (AM) ,X-ray computed tomography (XCT) - Abstract
The osseointegration in/around additively manufactured (AM) lattice structures of a new titanium alloy, Ti–19Nb–14Zr, was evaluated. Different lattices with increasingly high sidewalls gradually closing them were manufactured and implanted in sheep. After removal, the bone–interface implant (BII) and bone–implant contact (BIC) were studied from 3D X-ray computed tomography images. Measured BII of less than 10 µm and BIC of 95% are evidence of excellent osseointegration. Since AM naturally leads to a high-roughness surface finish, the wettability of the implant is increased. The new alloy possesses an increased affinity to the bone. The lattice provides crevices in which the biological tissue can jump in and cling. The combination of these factors is pushing ossification beyond its natural limits. Therefore, the quality and speed of the ossification and osseointegration in/around these Ti–19Nb–14Zr laterally closed lattice implants open the possibility of bone spline key of prostheses. This enables the stabilization of the implant into the bone while keeping the possibility of punctual hooks allowing the implant to be removed more easily if required. Thus, this new titanium alloy and such laterally closed lattice structures are appropriate candidates to be implemented in a new generation of implants. more...
- Published
- 2023
- Full Text
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39. Can Potential Defects in LPBF Be Healed from the Laser Exposure of Subsequent Layers? A Quantitative Study
- Author
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Alexander Ulbricht, Gunther Mohr, Simon J. Altenburg, Simon Oster, Christiane Maierhofer, and Giovanni Bruno
- Subjects
selective laser melting (SLM) ,additive manufacturing (AM) ,process monitoring ,infrared thermography ,optical tomography ,X-ray computed tomography (XCT) ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Additive manufacturing (AM) of metals and in particular laser powder bed fusion (LPBF) enables a degree of freedom in design unparalleled by conventional subtractive methods. To ensure that the designed precision is matched by the produced LPBF parts, a full understanding of the interaction between the laser and the feedstock powder is needed. It has been shown that the laser also melts subjacent layers of material underneath. This effect plays a key role when designing small cavities or overhanging structures, because, in these cases, the material underneath is feed-stock powder. In this study, we quantify the extension of the melt pool during laser illumination of powder layers and the defect spatial distribution in a cylindrical specimen. During the LPBF process, several layers were intentionally not exposed to the laser beam at various locations, while the build process was monitored by thermography and optical tomography. The cylinder was finally scanned by X-ray computed tomography (XCT). To correlate the positions of the unmolten layers in the part, a staircase was manufactured around the cylinder for easier registration. The results show that healing among layers occurs if a scan strategy is applied, where the orientation of the hatches is changed for each subsequent layer. They also show that small pores and surface roughness of solidified material below a thick layer of unmolten material (>200 µm) serve as seeding points for larger voids. The orientation of the first two layers fully exposed after a thick layer of unmolten powder shapes the orientation of these voids, created by a lack of fusion. more...
- Published
- 2021
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40. Nondestructive quantitative characterisation of material phases in metal additive manufacturing using multi-energy synchrotron X-rays microtomography.
- Author
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Xavier, Matheus S., Yang, Sam, Comte, Christophe, Bab-Hadiashar, Alireza, Wilson, Neil, and Cole, Ivan
- Subjects
- *
X-ray computed microtomography , *LASER deposition , *COMPUTED tomography , *STEEL manufacture , *MANUFACTURING processes , *SYNCHROTRONS - Abstract
Metal additive manufacturing (MAM) has found emerging application in the aerospace, biomedical and defence industries. However, the lack of reproducibility and quality issues are regarded as the two main drawbacks to AM. Both of these aspects are affected by the distribution of defects (e.g. pores) in the AM part. Computed tomography (CT) allows the determination of defect sizes, shapes and locations, which are all important aspects for the mechanical properties of the final part. In this paper, data-constrained modelling (DCM) with multi-energy synchrotron X-rays is employed to characterise the distribution of defects in 316L stainless steel specimens manufactured with laser metal deposition (LMD). It is shown that DCM offers a more reliable method to the determination of defect levels when compared to traditional segmentation techniques through the calculation of multiple volume fractions inside a voxel, i.e. by providing sub-voxel information. The results indicate that the samples are dominated by a high number of small light constituents (including pores) that would not be detected under the voxel size in the majority of studies reported in the literature using conventional thresholding methods. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
- Full Text
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41. Modelling heterogeneous coal-rock (HCR) failure patterns under dynamic impact loads using image-based finite element (FE) and discrete element (DE) model.
- Author
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Zheng, Kehong, Qiu, Bingjing, Wang, Zhenyu, Li, Jianping, and Gao, Kuidong
- Subjects
- *
IMPACT loads , *DYNAMIC loads , *IMPACT (Mechanics) , *INHOMOGENEOUS materials , *STRENGTH of materials , *COMPUTED tomography - Abstract
The paper described two different numerical 3D mesoscopic approaches (the meso-scale image-based FE and DE model) for quantitative and qualitative characterization of the dynamic impact mechanical behavior of HCR. The 3D meso-structure of HCR in calculations, which was directly obtained from real coal rock specimen using non-destructive XCT techniques, was modelled as a random heterogeneous two-phase material composed of coal and gangue respectively. Dynamic impact loading in three directions (x -, y -, and z -axis) were modelled to investigate the 3D meso-structure and different input energies effects on failure patterns of HCR. The very different qualitative and quantitative results demonstrated that the spatial distribution of mineral phases, loading directions and input energies have pronounced influenced on material strength as well as failure patterns of heterogeneous rock materials. The XCT image-based numerical model proved to be an effective tool that gives insights into the meso-deformation mechanisms of HCR undergoing dynamic impact failure behavior. Image 1 • Dynamic impact loading of HCR in three directions (x -, y - and z -axis) are modelled. • The effects of loading direction and impact velocity on failure patterns are studied. • The comparison results of the meso-scale image-based FE and DE model are discussed. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
- Full Text
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42. 3D ex-situ and in-situ X-ray CT process studies in particle technology – A perspective.
- Author
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Leißner, T., Diener, A., Löwer, E., Ditscherlein, R., Krüger, K., Kwade, A., and Peuker, U.A.
- Subjects
- *
COMPUTED tomography , *BULK solids handling , *PARTICLES , *PRODUCTION engineering , *X-rays - Abstract
• A brief review on XCT in the field of powder technology is given. • Selected examples show the application of XCT in process engineering. • Future applications of XCT in process engineering are discussed. X-ray computed tomography (XCT) has seen significant development in scan time and spatial resolution over the last decades. It is now increasingly used in the field of particle technology including ex-situ and in-situ applications to study time-lapse processes. This is due to its non-destructive principle giving 3D information on the inner structure and composition of specimens. This article shortly summarizes the field of XCT focusing on terms relevant for particle technology. It also gives a brief outlook on promising directions of development, which may significantly improve XCT. Using different examples from bulk solids handling, flow in porous structures and filtration, the monitoring of concentration differences and the fracture of particles, the application of XCT in particle technology is shown and its perspective is discussed. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
- Full Text
- View/download PDF
43. 2D automated SEM and 3D X-ray computed tomography study on inclusion analysis of steels.
- Author
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Bandi, Bharath, Santillana, Begona, Tiekink, Wouter, Koura, Nadia, Williams, Mark, and Srirangam, Prakash
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COMPUTED tomography , *STEEL analysis , *MILD steel , *TITANIUM nitride , *CALCIUM aluminate - Abstract
In this research work, inclusion analysis was done on titanium micro-alloyed low carbon steels using automated scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS), and 3D X-ray computed tomography (XCT) techniques. Automated SEM/EDS analysis provided the information about the average size, number, shape, and the composition of the inclusions. The inclusions are categorized as calcium aluminates, titanium nitrides, and 'other' inclusions with an average size of 1.66, 1.52, and 1.31 µm, respectively. To estimate the actual amount of inclusions present and to understand their 3D morphologies, XCT analysis was done at two different resolutions of 1.8 µm and 590 nm. The employment of these resolutions enabled the technique to detect huge number of inclusions with a wide size range from 0.75 to 201.4 µm. Moreover, the XCT technique revealed the presence of complex irregular shaped inclusions. Effective combination of these two techniques for inclusion analysis gives complete quantified information about the inclusions present in steels. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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44. Beam oscillation, porosity formation and fatigue properties of electron beam welded Ti-6Al-4V alloy.
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Kar, Jyotirmaya, Chakrabarti, Debalay, Roy, Sanat Kumar, and Roy, Gour Gopal
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ELECTRON beam welding , *COMPUTED tomography , *POROSITY , *WELDING , *METALWORK - Abstract
Abstract Butt joints of Ti-6Al-4V plates were produced by electron beam welding process using both oscillating and non-oscillating beams. The joints were then inspected using X-ray computed tomography technique for three-dimensional observation of porosities across the weld zone. Joints produced using beam oscillation were found to have contained well dispersed and significantly lower porosity content than the one made using non-oscillating beam. An optimum pore diameter of 312 μm has been identified below which the gas bubbles will be entrapped as pores under the used welding conditions. The corresponding strain-controlled fatigue tests demonstrated significantly higher fatigue life for oscillating beam joints than their non-oscillating beam counterpart. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
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45. Quantitative In-situ Analysis of Water Transport in Concrete Completed Using X-ray Computed Tomography.
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Oesch, Tyler, Weise, Frank, Meinel, Dietmar, and Gollwitzer, Christian
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CONCRETE ,WATER transfer ,MOISTURE measurement ,COMPUTED tomography ,X-ray scattering - Abstract
This paper describes a novel methodology for quantitative in-situ moisture measurement without tracking agents using X-ray computed tomography (XCT). The high levels of greyscale precision required for the measurement of moisture without tracking agents resulted in the need for an additional image calibration procedure to correct for water-related X-ray scattering and for equipment-variability-related artefacts arising during in-situ testing. This calibration procedure was developed on the basis of existing principles of XCT image correction. Resulting images of moisture distribution exhibit a high level of agreement with expected material behaviour. This research demonstrated that XCT can be successfully used to measure both moisture front movement over time and changes in 3D moisture distribution within samples. This approach to moisture measurement lays the groundwork for the planned future investigation of the interaction between cracking induced by varying chemical and mechanical processes and water transport in concrete. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
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46. Ultra-thin composites membrane for deployable structures: XCT driven characterization and FE modeling of folding structure.
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Din, Israr Ud, Ahmed, Adnan, Tarek, Farah, Cantwell, Wesley, and Khan, Kamran A.
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DNA folding , *COMPUTED tomography - Abstract
Light-weight, ultra-thin, high performance, origami-inspired deployable folding structures can be fabricated by simulating various designs and material combinations. In this study, an XCT-driven finite element (FE) model of a building block in a typical full-scale origami structure consisting of stiff and fold regions was developed. Following our previous work, the stiff region of the fold sample was fabricated using a hot compression molding technique whereas hand layup was employed for the fold region. XCT-driven FE based homogenization was carried out on an RVE of real microstructure of both ultra-thin composite laminates. The FE homogenization results were found to be in good agreement with the experimentally-measured effective stiffness properties of both the stiff and fold regions, with a maximum error of ∼10%. Folding tests were conducted on a simple fold and the force vs. displacement and moment vs. curvature curves were plotted. The applicability of XCT-driven FE modeling to simulate foldable structures were demonstrated using post-buckling and bending analysis available in the FE software ABAQUS®. A uniform and symmetric fold curvature, along with the corresponding force vs. displacement response were predicted using XCT-driven FE techniques and found to be in good agreement with data from the experimental tests. The peak force predicted by the FE model showed an error of ∼5.2% compared to the experimental fold test. [Display omitted] [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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47. Estimating the permeability of soils under different tillage practices and cropping systems: Roles of the three percolating pore radii derived from X-ray CT.
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Qian, Yongqi, Yang, Xiaofan, Zhang, Zhongbin, Li, Xueying, Zheng, Jinyu, and Peng, Xinhua
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SOIL permeability , *TILLAGE , *NO-tillage , *COMPUTED tomography , *ROCK permeability , *POROSITY , *SOIL management , *CROP management - Abstract
Soil permeability associated with pore characteristics is a critical factor affecting water and nutrient transport in agricultural fields. However, which soil pore characteristics determine soil permeability remains inconclusive due to high heterogeneity of soil pore structure affected by soil and crop management practices. The objective of this study was to compare the pore characteristics of soils under various field management and assess the performance of different pore radii in estimating soil permeability. In this study, we utilized X-ray computed tomography (XCT) to quantify the pore characteristics of soil cores from three treatments: no-tillage under continuous maize cropping (NT-MM), no-tillage under continuous soybean cropping (NT-SS) and conventional tillage under continuous maize cropping (CT-MM). Subsequently, we calculated the permeability with pore-scale numerical simulations directly based on XCT images. Our results revealed that compared to the NT-MM treatment, the NT-SS and CT-MM treatments significantly increased soil porosity of > 200 µm pore classes (soil depths of 2–8 cm and 2–14 cm), as well as pore compactness, specific surface area, fractal dimension, and global connectivity. Among the three XCT-derived pore radii, the critical pore radius (CR) exhibited excellent performance in estimating permeability for samples from the NT-SS and CT-MM treatments, surpassing the hydraulic radius (HR) and mean pore radius of the limiting layer (MRLL). For samples from the NT-MM treatment, the CR and MRLL had similar estimation capabilities (R2 = 0.429, P = 0.110), but both were not as good as the HR (R2 = 0.539, P = 0.060). Furthermore, when estimating the permeability of all the aforementioned soil samples, the CR demonstrated the best estimation performance (R2 = 0.838, P < 0.001). In conclusion, utilizing CR as a predictor for estimating permeability in naturally structured soils is a good choice, which provides valuable insights into improving the accuracy of estimating soil permeability. • Soil permeability was estimated by numerical simulation based on XCT images. • Relative to NT, the CT presented greater XCT-derived porosity at plow layer but less biopores. • Relative to MM, the SS increased the XCT-derived porosity with larger biopores. • The critical pore radius estimated permeability best among the three pore radii. [ABSTRACT FROM AUTHOR] more...
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- 2024
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48. Laboratory X-ray Microscopy Study of Microcrack Evolution in a Novel Sodium Iron Titanate-Based Cathode Material for Li-Ion Batteries
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Viktor Shapovalov, Kristina Kutukova, Sebastian Maletti, Christian Heubner, Vera Butova, Igor Shukaev, Alexander Guda, Alexander Soldatov, Ehrenfried Zschech, and Publica
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X-ray computed tomography (XCT) ,X-ray computed tomography ,cathode material ,Crystallography ,General Chemical Engineering ,crack formation ,crack propagation ,battery ,operando study ,X-ray microscopy ,3D imaging ,degradation process ,Condensed Matter Physics ,Inorganic Chemistry ,QD901-999 ,General Materials Science ,high-resolution 3D imaging - Abstract
The long-term performance of batteries depends strongly on the 3D morphology of electrode materials. Morphological changes, i.e., particle fracture and surface deterioration, are among the most prominent sources of electrode degradation. A profound understanding of the fracture mechanics of electrode materials in micro- and nanoscale dimensions requires the use of advanced in situ and operando techniques. In this paper, we demonstrate the capabilities of laboratory X-ray microscopy and nano X-ray computed tomography (nano-XCT) for the non-destructive study of the electrode material’s 3D morphology and defects, such as microcracks, at sub-micron resolution. We investigate the morphology of Na0.9Fe0.45Ti1.55O4 sodium iron titanate (NFTO) cathode material in Li-ion batteries using laboratory-based in situ and operando X-ray microscopy. The impact of the morphology on the degradation of battery materials, particularly the size- and density-dependence of the fracture behavior of the particles, is revealed based on a semi-quantitative analysis of the formation and propagation of microcracks in particles. Finally, we discuss design concepts of the operando cells for the study of electrochemical processes. more...
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- 2022
49. Layer-wise spatial modeling of porosity in additive manufacturing.
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Liu, Jia (Peter), Liu, Chenang, Bai, Yun, Rao, Prahalada, Williams, Christopher B., and Kong, Zhenyu (James)
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POROSITY , *FATIGUE life , *THREE-dimensional printing , *ONLINE monitoring systems , *COMPUTED tomography , *GAUSSIAN processes - Abstract
The objective of this work is to model and quantify the layer-wise spatial evolution of porosity in parts made using Additive Manufacturing (AM) processes. This is an important research area because porosity has a direct impact on the functional integrity of AM parts such as their fatigue life and strength. To realize this objective, an Augmented Layer-wise Spatial log Gaussian Cox process (ALS-LGCP) model is proposed. The ALS-LGCP approach quantifies the spatial distribution of pores within each layer of the AM part and tracks their sequential evolution across layers. Capturing the layer-wise spatial behavior of porosity leads to a deeper understanding of where (at what location), when (at which layer), and to what severity (size and number) pores are formed. This work therefore provides a mathematical framework for identifying specific pore-prone areas in an AM part, and tracking the evolution of porosity in AM parts in a layer-wise manner. This knowledge is essential for initiating remedial corrective actions to avoid porosity in future parts, e.g., by changing the process parameters or part design. The ALS-LGCP approach proposed herein is a significant improvement over the current scalar metric used to quantify porosity, namely, the percentage porosity relative to the bulk part volume. In this article, the ALS-LGCP approach is tested for metal parts made using a binder jetting AM process to model the layer-wise spatial behavior of porosity. Based on offline, non-destructive X-Ray computed tomography (XCT) scan data of the part the approach identifies those areas with high risk of porosity with statistical fidelity approaching 85% (F-score). While the proposed work uses offline XCT data, it takes the critical first-step from a data analytics perspective for taking advantage of the recently reported breakthroughs in online, in-situ X-Ray-based monitoring of AM processes. Further, the ALS-LGCP approach is readily extensible for porosity analysis in other AM processes; our future forays will focus on improving the computational tractability of the approach for online monitoring. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
- Full Text
- View/download PDF
50. Effect of weld parameters on porosity formation in electron beam welded Zircaloy-4 joints: X-ray tomography study.
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Bandi, Bharath, Dinda, Soumitra Kumar, Kar, Jyotirmaya, Roy, Gour Gopal, and Srirangam, Prakash
- Subjects
- *
ELECTRON beams , *POROSITY , *COMPUTED tomography , *RAMAN spectroscopy , *WELDING - Abstract
Abstract Zircaloy-4 to Zircaloy-4 (Zr-4) similar butt joints were prepared using Electron Beam Welding (EBW) technique under different weld conditions such as with beam oscillation, without beam oscillation and at different welding speeds. Three-dimensional (3D) visualisation of porosity in weld joints was carried out using X-ray computed tomography (XCT) technique. Quantification of porosity such as the average size, number and shape of the pores were evaluated and compared among weld joints produced under different conditions. XCT results show that the porosity of the welds increased substantially with the increase in the weld speed. More interestingly, the results also show that there is a significant decrease in porosity of the joint produced with beam oscillation condition. An increase in weld speed from 700 mm/min to 1000 mm/min resulted in a significant increase in pore density (from 16 to 313 per mm3) and it was observed that the average size of the macro pores increased from 96.4 μm to 121.5 μm. The joints prepared with beam oscillation produced least number of pores with minimum percentage of macro pores and maximum percentage of spherical pores in it. Raman spectroscopy results confirmed the presence of hydrogen gas in pores of all the weld joints. Highlights • EBW of Zircaloy-4 was carried out as a function of with beam oscillation, without beam oscillation and at different welding speeds. • Quantification of porosity in EBW Zircaloy-4 joints was carried out using XCT technique. • The application of beam oscillation resulted in smaller size pores with less in number compared to without beam oscillation condition. [ABSTRACT FROM AUTHOR] more...
- Published
- 2018
- Full Text
- View/download PDF
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