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Publications (10 of 44) Show all publications
Sandin, O., Rodriguez, J. M., Larour, P., Parareda, S., Frómeta, D., Hammarberg, S., . . . Casellas, D. (2024). A particle finite element method approach to model shear cutting of high-strength steel sheets. Computational Particle Mechanics
Open this publication in new window or tab >>A particle finite element method approach to model shear cutting of high-strength steel sheets
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2024 (English)In: Computational Particle Mechanics, ISSN 2196-4378Article in journal (Refereed) Epub ahead of print
Place, publisher, year, edition, pages
Springer Nature, 2024
National Category
Applied Mechanics Other Materials Engineering
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-104322 (URN)10.1007/s40571-023-00708-5 (DOI)001156076500001 ()2-s2.0-85184256463 (Scopus ID)
Note

Funder: Horizon 2020 (101006844); RFCS (847213);

Available from: 2024-02-21 Created: 2024-02-21 Last updated: 2024-02-21
Wessling, A., Larsson, S. & Kajberg, J. (2024). A statistical bonded particle model study on the effects of rock heterogeneity and cement strength on dynamic rock fracture. Computational Particle Mechanics, 11(3), 1313-1327
Open this publication in new window or tab >>A statistical bonded particle model study on the effects of rock heterogeneity and cement strength on dynamic rock fracture
2024 (English)In: Computational Particle Mechanics, ISSN 2196-4378, Vol. 11, no 3, p. 1313-1327Article in journal (Refereed) Published
Abstract [en]

Numerical modelling and simulation can be used to gain insight about rock excavation processes such as rock drilling. Since rock materials are heterogeneous by nature due to varying mechanical and geometrical properties of constituent minerals, laboratory observations exhibit a certain degree of unpredictability, e.g. with regard to measured strength and crack propagation. In this work, a recently published heterogeneous bonded particle model is further developed and used to investigate dynamic rock fracture in a Brazilian disc test. The rock heterogeneities are introduced in two steps—a geometrical heterogeneity due to statistically distributed grain sizes and shapes, and a mechanical heterogeneity by distributing mechanical properties using three Weibull distributions. The first distribution is used for assigning average bond properties of the grains, the second one for the intragranular bond properties and the third one for the bond properties of the intergranular cementing. The model is calibrated for Kuru black diorite using previously published experimental data from high-deformation rate tests of Brazilian discs in a split-Hopkinson pressure bar device, where high-speed imaging was used to detect initiations of cracks and their growth. A parametric study is conducted on the Weibull heterogeneity index of the average bond properties and the grain cement strength and evaluated in terms of crack initiation and propagation, indirect tensile stress, strain and strain rate. The results show that this modelling approach is able to reproduce key phenomena of the dynamic rock fracture, such as stochastic crack initiation and propagation, as well as the magnitude and variations of measured quantities. Furthermore, the cement strength is found to be a key parameter for crack propagation path and time, overloading magnitudes and indirect tensile strain rate.

Place, publisher, year, edition, pages
Springer Nature, 2024
Keywords
DEM, Heterogeneous, Rock, Split-Hopkinson pressure bar
National Category
Other Civil Engineering
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-103013 (URN)10.1007/s40571-023-00688-6 (DOI)001103979400001 ()2-s2.0-85176935312 (Scopus ID)
Projects
DigiRock
Funder
Vinnova, 2021-04695
Note

Validerad;2024;Nivå 2;2024-06-26 (joosat);

Full text license: CC BY

Available from: 2023-11-27 Created: 2023-11-27 Last updated: 2024-06-26Bibliographically approved
Jonsson, S. & Kajberg, J. (2023). Evaluation of Crashworthiness Using High-Speed Imaging, 3D Digital Image Correlation, and Finite Element Analysis. Metals, 13(11), Article ID 1834.
Open this publication in new window or tab >>Evaluation of Crashworthiness Using High-Speed Imaging, 3D Digital Image Correlation, and Finite Element Analysis
2023 (English)In: Metals, E-ISSN 2075-4701, Vol. 13, no 11, article id 1834Article in journal (Refereed) Published
Abstract [en]

To promote the use of newhigh-strengthmaterials in the automotive industry, the evaluation of crashworthiness is essential, both in terms of finite element (FE) analysis aswell as validation experiments. Thiswork proposes an approach to address the crash performance through high-speed imaging combined with 3D digital image correlation (3D-DIC). By tracking the deformation of the component continuously, cracks can be identified and coupled to the load and intrusion history of the experiment. The so-called crash index (CI) and its decreasing rate (CIDR) can then be estimated using only one single (or a few) component, instead of a set of components with different levels of intrusion and crushing. Crash boxes were axially and dynamically compressed to evaluate the crashworthiness of TRIP-aided bainite ferrite steel and press-hardenable steel. Acalibrated rate-dependent constitutivemodel, and a phenomenological damage model were used to simulate the crash box testing. The absorbed energy, the plastic deformation, and the CIDR were evaluated and compared to the experimentally counterparts. When applying the proposed method to evaluate the CIDR, a good agreement was found when using CI:s reported by other authors using large sets of crash boxes. The FE analyses showed a fairly good agreement with some underestimation in terms of energy absorptions. The crack formation was overestimated resulting in too high a predicted CIDR. It is concluded that the proposed method to evaluate the crashworthiness is promising. To improve the modelling accuracy, better prediction of the crack formation is needed and the introduction of the intrinsic material property, fracture toughness, is suggested for future investigations and model improvements.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
crashworthiness, crash index, third-generation AHSS, 3D digital image correlation, high strain rate, damage modelling
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-101999 (URN)10.3390/met13111834 (DOI)001113335200001 ()2-s2.0-85177648214 (Scopus ID)
Funder
EU, Horizon 2020, FormPlanet, no. 814519
Note

Validerad;2023;Nivå 2;2023-11-01 (joosat);

Part of special issue: Mechanical Behaviors and Damage Mechanisms of Metallic Materials

CC BY 4.0 License

Available from: 2023-11-01 Created: 2023-11-01 Last updated: 2024-03-19Bibliographically approved
Suarez, L., Jonsén, P. & Kajberg, J. (2023). Valorization of Air-Cooled EAF Manganese Slag in Comminution Processes: an Investigation into the Breakage Characterization. Mining, Metallurgy & Exploration, 40(6), 2449-2462
Open this publication in new window or tab >>Valorization of Air-Cooled EAF Manganese Slag in Comminution Processes: an Investigation into the Breakage Characterization
2023 (English)In: Mining, Metallurgy & Exploration, ISSN 2524-3462, Vol. 40, no 6, p. 2449-2462Article in journal (Refereed) Published
Abstract [en]

In recent years, slag, a residue from pyrometallurgical processes, has become more attractive in circular economy frameworks to increase the efficient use of resources throughout the life cycle of steel products and help in the reduction of carbon emissions. Its applicability is strongly dependent on the particle size, and therefore, the optimization of breaking processes should be approached by increasing the knowledge of the dynamics of slag to promote fracture. Increasing the knowledge on the mechanical response of manganese slag opens up the potential for the development of cost-effective numerical models, e.g., constitutive models based on inverse engineering calibration frameworks or digital twins. In this study, rate-dependent tests of manganese slag have been performed using a split Hopkinson pressure bar device for testing its dynamic mechanical response. In order to obtain information about the crack initiation and fracture process, 2D ultra-high speed imaging was implemented with a sampling frequency of 663,200 fps for diametrically loaded specimens. Full-field deformation measurements using digital image correlation (DIC) techniques showed a staggered fracture process where failure points on mechanical response curves vary due to the internal events happening in the material. Localized frictional occurrences and inertial effects acting inside the pre-cracked matrix have a strong effect on the global mechanical response, and therefore, a great variability of strengths was obtained.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Brazilian disc, SHPB, Ultra-high speed imaging, DIC, Slag
National Category
Other Mechanical Engineering Metallurgy and Metallic Materials
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-102325 (URN)10.1007/s42461-023-00856-5 (DOI)001097203500002 ()2-s2.0-85175641766 (Scopus ID)
Projects
GREENY - Grinding Energy Efficiency
Funder
EU, Horizon 2020
Note

Validerad;2024;Nivå 2;2024-04-02 (hanlid);

Full text license: CC BY 4.0

Funder: EIT Raw Materials (18009)

Available from: 2023-11-06 Created: 2023-11-06 Last updated: 2024-04-02Bibliographically approved
Wessling, A., Larsson, S., Jonsén, P. & Kajberg, J. (2022). A Brittle and Heterogeneous Bonded Discrete Element Model of Wide Applicability. In: Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson (Ed.), Svenska Mekanikdagar 2022: . Paper presented at Svenska Mekanikdagarnam2022, Luleå, Sweden, June 15-16, 2022. Luleå tekniska universitet
Open this publication in new window or tab >>A Brittle and Heterogeneous Bonded Discrete Element Model of Wide Applicability
2022 (English)In: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå tekniska universitet, 2022Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Luleå tekniska universitet, 2022
National Category
Other Materials Engineering
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-92496 (URN)
Conference
Svenska Mekanikdagarnam2022, Luleå, Sweden, June 15-16, 2022
Available from: 2022-08-16 Created: 2022-08-16 Last updated: 2023-09-05Bibliographically approved
Wessling, A., Larsson, S., Jonsén, P. & Kajberg, J. (2022). A statistical DEM approach for modelling heterogeneous brittle materials. Computational Particle Mechanics, 9(4), 615-631
Open this publication in new window or tab >>A statistical DEM approach for modelling heterogeneous brittle materials
2022 (English)In: Computational Particle Mechanics, ISSN 2196-4378, Vol. 9, no 4, p. 615-631Article in journal (Refereed) Published
Abstract [en]

By utilizing numerical models and simulation, insights about the fracture process of brittle heterogeneous materials can be gained without the need for expensive, difficult, or even impossible, experiments. Brittle and heterogeneous materials like rocks usually exhibit a large spread of experimental data and there is a need for a stochastic model that can mimic this behaviour. In this work, a new numerical approach, based on the Bonded Discrete Element Method, for modelling of heterogeneous brittle materials is proposed and evaluated. The material properties are introduced into the model via two main inputs. Firstly, the grains are constructed as ellipsoidal subsets of spherical discrete elements. The sizes and shapes of these ellipsoidal subsets are randomized, which introduces a grain shape heterogeneity Secondly, the micromechanical parameters of the constituent particles of the grains are given by the Weibull distribution. The model was applied to the Brazilian Disc Test, where the crack initiation, propagation, coalescence and branching could be investigated for different sets of grain cement strengths and sample heterogeneities. The crack initiation and propagation was found to be highly dependent on the level of heterogeneity and cement strength. Specifically, the amount of cracks initiating from the loading contact was found to be more prevalent for cases with higher cement strength and lower heterogeneity, while a more severe zigzag shaped crack pattern was found for the cases with lower cement strength and higher heterogeneity. Generally, the proposed model was found to be able to capture typical phenomena associated with brittle heterogeneous materials, e.g. the unpredictability of the strength in tension and crack properties.

Place, publisher, year, edition, pages
Springer Nature, 2022
Keywords
Bonded DEM, Heterogeneous brittle materials, Fracture, Brazilian disc, Weibull
National Category
Other Mechanical Engineering Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-83907 (URN)10.1007/s40571-021-00434-w (DOI)000692075800001 ()2-s2.0-85114114019 (Scopus ID)
Projects
GEOFIT
Funder
EU, Horizon 2020, 792210
Note

Validerad;2022;Nivå 2;2022-07-26 (hanlid)

Available from: 2021-04-23 Created: 2021-04-23 Last updated: 2024-03-19Bibliographically approved
Hammarberg, S., Kajberg, J., Larsson, S., Moshfegh, R. & Jonsén, P. (2022). Calibration of orthotropic plasticity- and damage models for micro-sandwich materials. SN Applied Sciences, 4(6), Article ID 182.
Open this publication in new window or tab >>Calibration of orthotropic plasticity- and damage models for micro-sandwich materials
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2022 (English)In: SN Applied Sciences, ISSN 2523-3963, E-ISSN 2523-3971, Vol. 4, no 6, article id 182Article in journal (Refereed) Published
Abstract [en]

Sandwich structures are commonly used to increase bending-stiffness without significantly increasing weight. In particular, micro-sandwich materials have been developed with the automotive industry in mind, being thin and formable. In the present work, it is investigated if micro-sandwich materials may be modeled using commercially available material models, accounting for both elasto-plasticity and fracture. A methodology for calibration of both the constitutive- and the damage model of micro-sandwich materials is presented. To validate the models, an experimental T-peel test is performed on the micro-sandwich material and compared with the numerical models. The models are found to be in agreement with the experimental data, being able to recreate the force response as well as the fracture of the micro-sandwich core.

Place, publisher, year, edition, pages
Springer Nature, 2022
Keywords
Micro sandwich, Hybrix, Lightweight, Modeling, T-peel test
National Category
Composite Science and Engineering
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-85075 (URN)10.1007/s42452-022-05060-6 (DOI)000798485800004 ()2-s2.0-85130368530 (Scopus ID)
Funder
EU, Horizon 2020, 814517 Form-Planet
Note

Validerad;2022;Nivå 2;2022-06-03 (hanlid)

Available from: 2021-06-08 Created: 2021-06-08 Last updated: 2023-09-05Bibliographically approved
Wessling, A., Kajberg, J., Larsson, S., Jonsén, P., Ramírez Sandoval, G. & Vilaseca Llosada, M. (2022). Discrete Element Modelling of Rock Drilling. In: European Geothermal Congress 2022: . Paper presented at European Geothermal Congress 2022, October 17-21, 2022, Berlin, Germany. , Article ID 272.
Open this publication in new window or tab >>Discrete Element Modelling of Rock Drilling
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2022 (English)In: European Geothermal Congress 2022, 2022, article id 272Conference paper, Published paper (Refereed)
Abstract [en]

Percussive rotary drilling is recognized as the mostefficient method for hard rock drilling. Despite clearadvantages over conventional rotary methods, there arestill some uncertainties associated with percussivedrilling. For geothermal applications, drilling accountsfor a large portion of the total cost. Specifically, thewear of drill bits when drilling in hard rock is apredominant cost factor and drilling parameters areoften based on the experience of the field operator.Within the framework of the H2020 project GEOFIT,numerical simulations of percussive drilling areperformed in order to evaluate the rock drilling processand gain insight about the trade-off between wear andRate of Penetration (ROP). In the simulations, the rockmaterial was represented by the Bonded DiscreteElement Method (BDEM), the drill bit by the FiniteElement Method (FEM), the drilling fluid by theParticle Finite Element Method (PFEM) and theabrasive wear on the surface of the drill bit wasrepresented by Archard’s wear law. The drillingsimulations were conducted for two rock materials; asedimentary rock material corresponding to what wasfound when drilling at the GEOFIT pilot site in AranIslands, Ireland, and a harder reference rock similar togranite. The results show that, at a drill bit impact forceof 10 kN, the ROP in the sedimentary rock was 6.3times faster than for granite. When increasing theimpact force to 40 and 50 kN, however, the ROP for thesedimentary rock is only 1.9 and 1.6 times faster,respectively. Furthermore, the wear rate decreased withincreased impact force when drilling in the granite rock.For the sedimentary rock, however, the loadingresulting in the best trade-off between abrasive wearand ROP was the second highest loading of 40 kN,which suggests that an increase in impact energy mayincrease the rate of penetration but may not beeconomically motivated.

National Category
Other Civil Engineering
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-96967 (URN)978-2-9601946-2-3 (ISBN)
Conference
European Geothermal Congress 2022, October 17-21, 2022, Berlin, Germany
Projects
GEOFIT
Available from: 2023-05-02 Created: 2023-05-02 Last updated: 2023-09-05Bibliographically approved
Wessling, A. & Kajberg, J. (2022). Dynamic Compressive and Tensile Characterisation of Igneous Rocks Using Split-Hopkinson Pressure Bar and Digital Image Correlation. Materials, 15(22), Article ID 8264.
Open this publication in new window or tab >>Dynamic Compressive and Tensile Characterisation of Igneous Rocks Using Split-Hopkinson Pressure Bar and Digital Image Correlation
2022 (English)In: Materials, E-ISSN 1996-1944, Vol. 15, no 22, article id 8264Article in journal (Refereed) Published
Abstract [en]

The dynamic fracture process of rock materials is of importance for several industrial applications, such as drilling for geothermal installation. Numerical simulation can aid in increasing the understanding about rock fracture; however, it requires precise knowledge about the dynamical mechanical properties alongside information about the initiation and propagation of cracks in the material. This work covers the detailed dynamic mechanical characterisation of two rock materials—Kuru grey granite and Kuru black diorite—using a Split-Hopkinson Pressure Bar complemented with high-speed imaging. The rock materials were characterised using the Brazilian disc and uniaxial compression tests. From the high-speed images, the instant of fracture initiation was estimated for both tests, and a Digital Image Correlation analysis was conducted for the Brazilian disc test. The nearly constant tensile strain in the centre was obtained by selecting a rectangular sensing region, sufficiently large to avoid complicated local strain distributions appearing between grains and at voids. With a significantly high camera frame rate of 671,000 fps, the indirect tensile strain and strain rates on the surface of the disc could be evaluated. Furthermore, the overloading effect in the Brazilian disc test is evaluated using a novel methodology consisting of high-speed images and Digital Image Correlation analysis. From this, the overloading effects were found to be 30 and 23%. The high-speed images of the compression tests indicated fracture initiation at 93 to 95% of the peak dynamic strength for granite and diorite, respectively. However, fracture initiation most likely occurred before this in a non-observed part of the sample. It is concluded that the indirect tensile strain obtained by selecting a proper size of the sensing region combined with the high temporal resolution result in a reliable estimate of crack formation and subsequent propagation.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
rock, dynamic mechanical properties, fracture, high-speed imaging, digital image correlation, Split-Hopkinson pressure bar
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-94378 (URN)10.3390/ma15228264 (DOI)000887520400001 ()36431749 (PubMedID)2-s2.0-85142756512 (Scopus ID)
Funder
EU, Horizon 2020, 792210
Note

Validerad;2022;Nivå 2;2022-11-30 (joosat);

Available from: 2022-11-30 Created: 2022-11-30 Last updated: 2024-07-04Bibliographically approved
Gustafsson, D., Parareda, S., Jonsén, P., Kajberg, J. & Olsson, E. (2022). Effect Of Cutting Clearance And Sandblasting On Fatigue Of Thick CP800 Steel Sheets. In: Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson (Ed.), Svenska Mekanikdagar 2022: . Paper presented at Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022. Luleå tekniska universitet
Open this publication in new window or tab >>Effect Of Cutting Clearance And Sandblasting On Fatigue Of Thick CP800 Steel Sheets
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2022 (English)In: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå tekniska universitet, 2022Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Luleå tekniska universitet, 2022
National Category
Mechanical Engineering
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-93157 (URN)
Conference
Svenska Mekanikdagarna 2022, Luleå, Sweden, June 15-16, 2022
Available from: 2022-09-21 Created: 2022-09-21 Last updated: 2023-09-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5218-396X

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