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Bahaloo, H., Gren, P., Casselgren, J., Forsberg, F. & Sjödahl, M. (2024). Capillary Bridge in Contact with Ice Particles Can Be Related to the Thin Liquid Film on Ice. Journal of cold regions engineering, 38(1), Article ID 04023021.
Open this publication in new window or tab >>Capillary Bridge in Contact with Ice Particles Can Be Related to the Thin Liquid Film on Ice
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2024 (English)In: Journal of cold regions engineering, ISSN 0887-381X, E-ISSN 1943-5495, Vol. 38, no 1, article id 04023021Article in journal (Refereed) Published
Abstract [en]

We experimentally demonstrate the presence of a capillary bridge in the contact between an ice particle and a smooth aluminum surface at a relative humidity of approximately 50% and temperatures below the melting point. We conduct the experiments in a freezer with a controlled temperature and consider the mechanical instability of the bridge upon separation of the ice particle from the aluminum surface at a constant speed. We observe that a liquid bridge forms, and this formation becomes more pronounced as the temperature approaches the melting point. We also show that the separation distance is proportional to the cube root of the volume of the bridge. We hypothesize that the volume of the liquid bridge can be used to provide a rough estimate of the thickness of the liquid layer on the ice particle since in the absence of other driving mechanisms, some of the liquid on the surface must have been pulled to the bridge area. We show that the estimated value lies within the range previously reported in the literature. With these assumptions, the estimated thickness of the liquid layer decreases from nearly 56 nm at T = −1.7°C to 0.2 nm at T = −12.7°C. The dependence can be approximated with a power law, proportional to (TM − T)−β, where β < 2.6 and TM is the melting temperature. We further observe that for a rough surface, the capillary bridge formation in the considered experimental conditions vanishes.

Place, publisher, year, edition, pages
American Society of Civil Engineers (ASCE), 2024
National Category
Infrastructure Engineering
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-102441 (URN)10.1061/JCRGEI.CRENG-738 (DOI)001143507100005 ()2-s2.0-85175442634 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-11-15 (sofila);

Full text license: CC BY

Available from: 2023-11-13 Created: 2023-11-13 Last updated: 2024-03-07Bibliographically approved
Bahaloo, H., Forsberg, F., Casselgren, J., Lycksam, H. & Sjödahl, M. (2024). Mapping of density-dependent material properties of dry manufactured snow using μCT. Applied Physics A: Materials Science & Processing, 130, Article ID 16.
Open this publication in new window or tab >>Mapping of density-dependent material properties of dry manufactured snow using μCT
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2024 (English)In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 130, article id 16Article in journal (Refereed) Published
Abstract [en]

Despite the significance of snow in various cryospheric, polar, and construction contexts, more comprehensive studies are required on its mechanical properties. In recent years, the utilization of μ CT has yielded valuable insights into snow analysis. Our objective is to establish a methodology for mapping density-dependent material properties for dry manufactured snow within the density range of 400–600 kg/m 3 utilizing μ CT imaging and step-wise, quasi-static, mechanical loading. We also aim to investigate the variations in the structural parameters of snow during loading. The three-dimensional (3D) structure of snow is captured using μ CT with 801 projections at the beginning of the experiments and at the end of each loading step. The sample is compressed at a temperature of − 18 o C using a constant rate of deformation (0.2 mm/min) in multiple steps. The relative density of the snow is determined at each load step using binary image segmentation. It varies from 0.44 in the beginning to nearly 0.65 at the end of the loading, which corresponds to a density range of 400–600 kg/m 3 . The estimated modulus and viscosity terms, obtained from the Burger’s model, show an increasing trend with density. The values of the Maxwell and Kelvin–Voigt moduli were found to range from 60 to 320 MPa and from 6 to 40 MPa, respectively. Meanwhile, the viscosity values for the Maxwell and Kelvin–Voigt models varied from 0.4 to 3.5 GPa-s, and 0.3–3.2 GPa-s, respectively, within the considered density range. In addition, Digital Volume Correlation (DVC) was used to calculate the full-field strain distribution in the specimen at each load step. The image analysis results show that, the particle size and specific surface area (SSA) do not change significantly within the studied range of loading and densities, while the sphericity of the particles is increased. The grain diameter ranges from approximately 100 μ m to nearly 400 μ m, with a mode of nearly 200 μ m. The methodology presented in this study opens up a path for an extensive statistical analysis of the material properties by experimenting more snow samples.

Place, publisher, year, edition, pages
Springer Nature, 2024
Keywords
Micro tomography, Material modeling, Stress-strain response, Digital volume correlation, Image analysis, Snow
National Category
Other Materials Engineering
Research subject
Experimental Mechanics; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-103511 (URN)10.1007/s00339-023-07167-y (DOI)001123446400001 ()2-s2.0-85179360802 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-02-26 (signyg);

Full text license: CC BY

Available from: 2024-01-08 Created: 2024-01-08 Last updated: 2024-04-18Bibliographically approved
Bahaloohoreh, H., Forsberg, F., Lycksam, H., Casselgren, J. & Sjödahl, M. (2024). Material mapping strategy to identify the density-dependent properties of dry natural snow. Applied Physics A: Materials Science & Processing, 130(2), Article ID 141.
Open this publication in new window or tab >>Material mapping strategy to identify the density-dependent properties of dry natural snow
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2024 (English)In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 130, no 2, article id 141Article in journal (Refereed) Published
Abstract [en]

The mechanical properties of natural snow play a crucial role in understanding glaciers, avalanches, polar regions, and snow-related constructions. Research has concentrated on how the mechanical properties of snow vary, primarily with its density; the integration of cutting-edge techniques like micro-tomography with traditional loading methods can enhance our comprehension of these properties in natural snow. This study employs CT imaging and uniaxial compression tests, along with the Digital Volume Correlation (DVC) to investigate the density-dependent material properties of natural snow. The data from two snow samples, one initially non-compressed (test 1) and the other initially compressed (test 2), were fed into Burger’s viscoelastic model to estimate the material properties. CT imaging with 801 projections captures the three-dimensional structure of the snow initially and after each loading step at -18C, using a constant deformation rate (0.2 mm/min). The relative density of the snow, ranging from 0.175 to 0.39 (equivalent to 160–360 kg/m), is determined at each load step through binary image segmentation. Modulus and viscosity terms, estimated from Burger’s model, exhibit a density-dependent increase. Maxwell and Kelvin–Voigt moduli range from 0.5 to 14 MPa and 0.1 to 0.8 MPa, respectively. Viscosity values for the Maxwell and Kelvin–Voigt models vary from 0.2 to 2.9 GPa-s and 0.2 to 2.3 GPa-s within the considered density range, showing an exponent between 3 and 4 when represented as power functions. Initial grain characteristics for tests 1 and 2, obtained through image segmentation, reveal an average Specific Surface Area (SSA) of around 55 1/mm and 40 1/mm, respectively. The full-field strain distribution in the specimen at each load step is calculated using the DVC, highlighting strong strain localization indicative of non-homogeneous behavior in natural snow. These findings not only contribute to our understanding of natural snow mechanics but also hold implications for applications in fields such as glacier dynamics and avalanche prediction.

Place, publisher, year, edition, pages
Springer Nature, 2024
Keywords
Material mapping, Micro tomography, Compression test, Digital volume correlation, Snow and ice
National Category
Other Materials Engineering
Research subject
Experimental Mechanics; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-104236 (URN)10.1007/s00339-024-07288-y (DOI)001153419300002 ()2-s2.0-85183678465 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-02-12 (joosat);

CC BY Full text license

Available from: 2024-02-12 Created: 2024-02-12 Last updated: 2024-03-07Bibliographically approved
Valizadeh, A., Skoglund, N., Forsberg, F., Lycksam, H. & Öhman, M. (2024). Role of surface morphology in bed particle layer formation on quartz bed particles in fluidized bed combustion of woody biomass. Fuel, 357(part A), Article ID 129702.
Open this publication in new window or tab >>Role of surface morphology in bed particle layer formation on quartz bed particles in fluidized bed combustion of woody biomass
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2024 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 357, no part A, article id 129702Article in journal (Refereed) Published
Abstract [en]

The influence of quartz bed particle surface morphology on the bed particle layer and crack layer formation process in fluidized bed combustion of woody biomass was investigated in this work. Bed material samples were collected at different sampling times from the startup with a fresh bed in industrial scale bubbling fluidized bed (BFB) and circulating fluidized bed (CFB) boilers, both utilizing woody biomass. X-ray microtomography (XMT) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) were employed to characterize bed particle layers and crack layers in the samples. Results showed that there is a noticeable difference between the bed layer characteristics over the so-called “concave” and “convex”-shaped morphologies on the bed particle surface with respect to layer formation. The concave areas are mainly covered with a thin inner layer, whilst the convex display a comparably thick inner layer and an outer layer. In addition, 3D images of the particles revealed that the crack layers mainly originate from concave areas where the particle is less protected by an outer bed particle layer in conjunction with cracks in the inner layer.

Place, publisher, year, edition, pages
Elsevier Ltd, 2024
Keywords
Bed material, Industrial-scale, Time-resolved, X-ray tomography
National Category
Energy Engineering
Research subject
Energy Engineering; Experimental Mechanics; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-101365 (URN)10.1016/j.fuel.2023.129702 (DOI)001070700200001 ()2-s2.0-85170026881 (Scopus ID)
Funder
Swedish Energy Agency, no. 46533-1
Note

Validerad;2023;Nivå 2;2023-09-18 (joosat);

CC BY 4.0 License;

For correction, see: Valizadeh A., Skoglund N., Forsberg F., Lycksam H., Öhman M., (2024). Corrigendum to “Role of surface morphology in bed particle layer formation on quartz bed particles in fluidized bed combustion of woody biomass” [Fuel 357(Part A) (2024) 129702]. Fuel. 364 131320. doi https://doi.org/10.1016/j.fuel.2024.131320

Available from: 2023-09-18 Created: 2023-09-18 Last updated: 2024-04-19Bibliographically approved
Valizadeh, A., Skoglund, N., Forsberg, F., Lycksam, H. & Öhman, M. (2023). A comparative study in 3D of bed particle layer characteristics in quartz and K-feldspar from fluidized bed combustion of woody biomass using X-ray microtomography. Paper presented at 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022. Fuel, 342, Article ID 127707.
Open this publication in new window or tab >>A comparative study in 3D of bed particle layer characteristics in quartz and K-feldspar from fluidized bed combustion of woody biomass using X-ray microtomography
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2023 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 342, article id 127707Article in journal (Refereed) Published
Abstract [en]

Bed particle layer and crack layer characteristics at different ages were studied for quartz and K-feldspar bed particles from a 30 MWth bubbling fluidized bed and a 90 MWth circulating fluidized bed, both using woody biomass as fuel. X-ray microtomography (XMT) was utilized to determine the bed particle layer distribution on the bed particles' surface. For each bed particle type, the average bed particle layer thickness as well as average volume fractions of the bed particle layer and crack layers to the entire bed particle volume were determined at three different bed particle ages by utilizing XMT analysis. Comparison of the two different bed particle types showed that K-feldspar retains a thinner bed particle layer in both conversion processes compared to quartz. Crack layers were observed extensively in quartz bed particles to the extent of 19.3 vol% and 32.1 vol% after 13 days in the BFB and the CFB, respectively, which could cause deposition of the bed particle fragments. On the contrary, K-feldspar has almost no tendency toward forming crack layers.

Place, publisher, year, edition, pages
Elsevier Ltd, 2023
Keywords
Bed particle layer formation, Combustion, Fluidized bed, Woody biomass, X-ray microtomography
National Category
Energy Engineering
Research subject
Energy Engineering; Experimental Mechanics; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-95819 (URN)10.1016/j.fuel.2023.127707 (DOI)000946690800001 ()2-s2.0-85148664496 (Scopus ID)
Conference
28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022
Funder
Swedish Energy Agency, 46533-1
Note

Godkänd;2023;Nivå 0;2023-03-08 (joosat);Konferensartikel i tidskrift

Part of special issue: 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Edited by Flemming J. Frandsen, Stanley Harding, Terry Wall, Markus Broström, Maria Zevenhoven

Licens fulltext: CC BY License

Available from: 2023-03-08 Created: 2023-03-08 Last updated: 2024-04-19Bibliographically approved
Bahaloohoreh, H., Gren, P., Casselgren, J., Forsberg, F. & Sjödahl, M. (2023). Capillary bridge in contact of ice particles reveals the thin liquid film on ice.
Open this publication in new window or tab >>Capillary bridge in contact of ice particles reveals the thin liquid film on ice
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2023 (English)Manuscript (preprint) (Other academic)
National Category
Other Engineering and Technologies not elsewhere specified
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-94783 (URN)
Available from: 2022-12-08 Created: 2022-12-08 Last updated: 2022-12-09
Forsberg, F., Fernberg, P., Al-Maqdasi, Z., Petkov, V., Lycksam, H. & Joffe, R. (2023). Efficient Use of Micro-Tomography for In-Depth Characterization of Composites. In: Brian G. Falzon; Conor McCarthy (Ed.), ICCM 2023 - Proceedings of the 2023 23rd International Conference on Composite Materials: . Paper presented at 23rd International Conference on Composite Materials (ICCM 2023), Belfast, United Kingdom, July 30-August 4, 2023. Queen's University Belfast, Northern Ireland
Open this publication in new window or tab >>Efficient Use of Micro-Tomography for In-Depth Characterization of Composites
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2023 (English)In: ICCM 2023 - Proceedings of the 2023 23rd International Conference on Composite Materials / [ed] Brian G. Falzon; Conor McCarthy, Queen's University Belfast, Northern Ireland , 2023Conference paper, Poster (with or without abstract) (Refereed)
Place, publisher, year, edition, pages
Queen's University Belfast, Northern Ireland, 2023
Series
ICCM International Conferences on Composite Materials
National Category
Applied Mechanics
Research subject
Experimental Mechanics; Polymeric Composite Materials; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-105053 (URN)2-s2.0-85187561369 (Scopus ID)
Conference
23rd International Conference on Composite Materials (ICCM 2023), Belfast, United Kingdom, July 30-August 4, 2023
Available from: 2024-04-11 Created: 2024-04-11 Last updated: 2024-04-11Bibliographically approved
Huber, J. A. & Forsberg, F. (2023). Local Stiffness of Softwood Based on Micro- and Macro-Scale Computed Tomography. In: J.F. Silva Gomes (Ed.), Proceedings ICM20: Experimental Mechanics in Engineering and Biomechanics: 20th International Conference on Experimental Mechanics. Paper presented at 20th International Conference on Experimental Mechanics (ICEM20), Porto, Portugal, July 2-7, 2023 (pp. 1001-1002). Institute of Science and Innovation in Mechanical and Industrial Engineering, Article ID 20161.
Open this publication in new window or tab >>Local Stiffness of Softwood Based on Micro- and Macro-Scale Computed Tomography
2023 (English)In: Proceedings ICM20: Experimental Mechanics in Engineering and Biomechanics: 20th International Conference on Experimental Mechanics / [ed] J.F. Silva Gomes, Institute of Science and Innovation in Mechanical and Industrial Engineering , 2023, p. 1001-1002, article id 20161Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Wood is a discontinuous cellular structure on a microscopic scale, but its mechanical behaviour resembles a continuum on a macroscopic scale. The structure of both domains can be studied by X-ray computed tomography (CT). A challenge for accurate CT-based models of wood is to set the values of the orthotropic stiffness tensor locally based on density. Micro-CT scans under in-situ loading may be used to estimate local stiffness in wood, based on strain fields derived from digital volume correlation. The goal of the present paper is to study how micro-CT scans of clearwood under in-situ loading can be used to predict stiffness locally as a function of the apparent macroscopic density, to improve the fidelity of FE models based on macro-CT scans.

Place, publisher, year, edition, pages
Institute of Science and Innovation in Mechanical and Industrial Engineering, 2023
Keywords
orthotropic stiffness tensor, fibre orientation, digital volume correlation, finite element analysis, image analysis, in-situ scanning
National Category
Wood Science Computer Vision and Robotics (Autonomous Systems) Applied Mechanics
Research subject
Wood Science and Engineering; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-99217 (URN)
Conference
20th International Conference on Experimental Mechanics (ICEM20), Porto, Portugal, July 2-7, 2023
Note

ISBN för värdpublikation: 978-989-54756-6-7

Available from: 2023-07-17 Created: 2023-07-17 Last updated: 2023-08-07Bibliographically approved
Mellin, P., Heino, S., Malmström, D., Karlsson, O., Sefer, B., Shipley, J., . . . Waernqvist, P. (2023). XCT-Tracking Pore Size Development, In PBF-LB Built 316L, During HIP And Subsequent Heat Treatments. In: Euro Powder Metallurgy 2023 (Euro PM2023) Proceedings: . Paper presented at Euro Powder Metallurgy 2023 Congress and Exhibition (Euro PM2023), Lisbon, Portugal, October 1-4, 2023. European Powder Metallurgy Association (EPMA)
Open this publication in new window or tab >>XCT-Tracking Pore Size Development, In PBF-LB Built 316L, During HIP And Subsequent Heat Treatments
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2023 (English)In: Euro Powder Metallurgy 2023 (Euro PM2023) Proceedings, European Powder Metallurgy Association (EPMA) , 2023Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
European Powder Metallurgy Association (EPMA), 2023
National Category
Metallurgy and Metallic Materials
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-103430 (URN)10.59499/EP235765571 (DOI)2-s2.0-85180376668 (Scopus ID)
Conference
Euro Powder Metallurgy 2023 Congress and Exhibition (Euro PM2023), Lisbon, Portugal, October 1-4, 2023
Available from: 2024-01-02 Created: 2024-01-02 Last updated: 2024-01-02Bibliographically approved
Bahaloohoreh, H., Eidevåg, T., Gren, P., Casselgren, J., Forsberg, F., Abrahamsson, P. & Sjödahl, M. (2022). Ice sintering: Dependence of sintering force on temperature, load, duration, and particle size. Journal of Applied Physics, 131(2), Article ID 025109.
Open this publication in new window or tab >>Ice sintering: Dependence of sintering force on temperature, load, duration, and particle size
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2022 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 131, no 2, article id 025109Article in journal (Refereed) Published
Abstract [en]

We present experiments along with an approximate, semi-analytic, close-form solution to predict ice sintering force as a function of temperature, contact load, contact duration, and particle size during the primary stage of sintering. The ice sintering force increases nearly linear with increasing contact load but nonlinear with both contact duration and particle size in the form of a power law. The exponent of the power law for size dependence is around the value predicted by general sintering theory. The temperature dependence of the sintering force is also nonlinear and follows the Arrhenius equation. At temperatures closer to the melting point, a liquid bridge is observed upon the separation of the contacted ice particles. We also find that the ratio of ultimate tensile strength of ice to the axial stress concentration factor in tension is an important factor in determining the sintering force, and a value of nearly 1.1 MPa can best catch the sintering force of ice in different conditions. We find that the activation energy is around 41.4KJ/mol41.4KJ/mol, which is close to the previously reported data. Also, our results suggest that smaller particles are “stickier” than larger particles. Moreover, during the formation of the ice particles, cavitation and surface cracking is observed which can be one of the sources for the variations observed in the measured ice sintering force.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2022
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-88792 (URN)10.1063/5.0073824 (DOI)000746515900007 ()2-s2.0-85123639304 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-01-17 (johcin)

Available from: 2022-01-17 Created: 2022-01-17 Last updated: 2022-12-09Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-7395-3302

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