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  • 1.
    Hammarberg, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    A Study on Sandwich Structures: Development, Mechanical Characterization and Numerical Modeling2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Legislative demands force the automotive industry to reduce greenhouse gas (GHG) emissions. At the same time, crashworthiness must not be compromised. A ve-hicle’s GHG emissions, such as carbon dioxide, is dependent on its fuel consump-tion. Lowering the vehicle weight, reducing fuel consumption, will therefor reduce emissions. Thus, high performance lightweight materials and structures are on demand. Several methods for achieving high-performance lightweight components are available. One of the most successful approaches has been replacing mild steels with press-hardened steels, e.g. ultra high strength steels (UHSS). In the press-hardening process, a low-alloyed boron steel blank is austenitized followed by simultaneously forming and cooling. By controlling cooling rates, a martensitic microstructure can be obtained, resulting in components with superior properties compared to mild steels. Other methods of achieving lightweight components in-clude the usage of sandwich structures where stiff skins are bonded to a low-density core. In the present thesis, several types of sandwich structures are studied both numerically and experimentally. A UHSS sandwich with a bidirectionlly corru-gated core, intended for stiffness application, is manufactured and evaluated in three-point bending. Finite element models are utilized to recreate the three-point bend test. A large amount of finite elements are required for precise discretization of the core. The number of finite elements are reduced by replacing the sandwich with an homogeneous, equivalent model with input data obtained from analyzing representative volume elements (RVEs) of the core, subjected to periodic and ho-mogeneous boundary conditions. Good agreement is found between experiments and finite element models. A UHSS sandwich with a partly perforated core is evaluated numerically for energy absorption applications. Several hole configu-rations for the core are evaluated with respect to specific energy absorption. A fracture criterion is utilized for the sandwich skins. Computational time is re-duced by homogenization of the core using a stress-resultant based constitutive model. It is found that the sandwich concept allows for an increase in specific energy absorption and that the computational time can be reduced while still be-ing able to predict energy absorption. An experimental methodology is developed for mechanical characterization of micro-sandwich materials. Tools are developed for loading the micro-sandwich in out-of-plane tension and shear, where digital image correlation is used for measuring displacements fields and fracture of the micro-sandwich core. Statistical methods are adopted for analyzing the variation in the mechanical properties of the micro-sandwich from which statistical means may be obtained. The experimental data is used as input for constitutive models, simulating the micro-sandwich material subjected to peeling, using a T-peel test. The numerical models are validated against experiments, found to agree within one standard deviation, suggesting that the experimental methodology produces robust data.The present work has thus presented methods, further increasing the usability of UHSS with regard to lightweighting, and explored how such components may be simulated numerically with adequate accuracy and reasonable computation time. Furthermore, the present thesis contributes by presenting methods for character-izing micro-sandwich materials, including statistical methods for analyzing scatter in mechanical properties, and how such sandwich materials may be modeled, tak-ing elasto-plasticity and damage into account. These results opens up possibilities for further development and optimization of lightweight constructions.

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  • 2.
    Hammarberg, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    A Study on Structural Cores for Lightweight Steel Sandwiches2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lightweight materials and structures are essential building blocks for a future with sustainable transportation and automotive industries. Incorporating lightweight materials and structures in today's vehicles, reduces weight and energy consumption while maintaining, or even improving, necessary mechanical properties and behaviors. Due to this, the environmental footprint can be reduced through the incorporation of lightweight structures and materials. 

    Awareness of the negative effects caused by pollution from emissions is ever increasing. Legislation, forced by authorities, drives industries to find better solutions with regard to the environmental impact. For the automotive industry, this implies more effective vehicles with respect to energy consumption. This can be achieved by introducing new, and improve current, methods of turning power into motion. An additional approach is reducing weight of the body in white (BIW) while maintaining crash worthiness to assure passenger safety. In addition to the structural integrity of the BIW, passenger safety is further increased through electrical systems integrated into the modern vehicle. Besides these safety systems, customers are also able to choose from a long list of gadgets to be fitted to the vehicle. As a result, the curb weight of vehicles are increasing, partly due to customer demands. In order to mitigate the increasing weights the BIW must be optimized with respect to weight, while maintaining its structural integrity and crash worthiness. To achieve this, new and innovative materials, geometries and structures are required, where the right material is used in the right place, resulting in a lightweight structure which can replace current configurations. 

    A variety of approaches are available for achieving lightweight, one of them being the press-hardening method, in which a heated blank is formed and quenched in the same process step. The result of the process is a component with greatly enhanced properties as compared to those of mild steel. Due to the properties of press hardened components they can be used to reduce the weight of the body-in-white. The process also allows for manufacturing of components with tailored properties, allowing the right material properties in the right place. 

    The present work aims to investigate, develop and in the end bring forth two types of light weight sandwiches; one intended for crash applications (Type I) and another for stiffness applications (Type II). Type I, based on press hardened boron steel, consists of a perforated core in between two face plates. To evaluate Type I's ability to absorb energy for crash applications a hat profile geometry is utilized. The hat profile is numerically subjected to loading from which the required energy to deform it can be found. These results are compared to those from a reference test, consisting of a hat profile based on solid steel and with an equivalent weight to that of the Type I hat profile. The aim is to minimize the weight of the core while maximizing the energy absorption. Type II consists of a bidirectional corrugated steel plate, placed in between two face plates. The geometry of the bidirectional core requires a large amount of finite elements for discretization causing a small time step and long simulation times. In order to reduce computational time a homogenization approach is suggested where the aim is to be able to predict stiffness of a planar sandwich at a reduced computational cost. 

    The numerical results from Type I show that it is possible to obtain a higher energy absorption per unit weight by introducing perforated cores in sandwich panels. Typically, energy absorption of such a panels were 20% higher as compared to a solid hat profile of equivalent weight, making it an attractive choice for reducing weight while maintaining performance. However, these results are awaiting experimental validation. The results from Type II show that it is possible, by introducing a homogenization procedure, to predict stiffness at a reduced computational cost. Validation by experiments were carried out as a sandwich panel was subjected to a three point bend in the laboratory. Numerical and experimental results agreed quite well, showing the possibilities of incorporating such panels into larger structure for stiffness applications.

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  • 3.
    Hammarberg, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Kajberg, Jörgen
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Larsson, Simon
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsén, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Ultra high strength steel sandwich for lightweight applications2020In: SN Applied Sciences, ISSN 2523-3963, E-ISSN 2523-3971, Vol. 2, no 6, article id 1040Article in journal (Refereed)
    Abstract [en]

    Methods for reducing weight of structural elements are important for a sustainable society. Over the recent years ultra high strength steel (UHSS) has been a successful material for designing light and strong components. Sandwich panels are interesting structural components to further explore areas where the benefits of UHSS can be utilized. The specific properties of sandwich panels make them suitable for stiffness applications and various cores have been studied extensively. In the present work, bidirectionally corrugated UHSS cores are studied experimentally and numerically. A UHSS core is manufactured by cold rolling and bonded to the skins by welding. Stiffness is evaluated experimentally in three-point bending. The tests are virtually reproduced using the finite element method. Precise discretization of the core requires large amounts of computational power, prolonging lead times for sandwich component development, which in the present work is addressed by homogenization, using an equivalent material formulation. Input data for the equivalent models is obtained by characterizing representative volume elements of the periodic cores under periodic boundary conditions. The homogenized panel reduces the number of finite elements and thus the computational time while maintaining accuracy. Numerical results are validated and agree well with experimental testing. Important findings from experimental and simulation results show that the suggested panels provide superior specific bending stiffness as compared to solid panels. This work shows that lightweight UHSS sandwiches with excellent stiffness properties can be manufactured and modeled efficiently. The concept of manufacturing a UHSS sandwich panel expands the usability of UHSS to new areas.

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  • 4.
    Hammarberg, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Kajberg, Jörgen
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Larsson, Simon
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Moshfegh, Ramin
    Lamera AB, Odhners gata 17, 42130 Västra Frölunda, Sweden.
    Jonsén, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Calibration of orthotropic plasticity- and damage models for micro-sandwich materials2022In: SN Applied Sciences, ISSN 2523-3963, E-ISSN 2523-3971, Vol. 4, no 6, article id 182Article in journal (Refereed)
    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.

  • 5.
    Hammarberg, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Kajberg, Jörgen
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Larsson, Simon
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Moshfegh, Ramin
    Lamera AB, A Odhners Gata 17, 421 30 Västra Frölunda, Sweden.
    Jonsén, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Novel Methodology for Experimental Characterization of Micro-Sandwich Materials2021In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 14, no 16, article id 4396Article in journal (Refereed)
    Abstract [en]

    Lightweight components are in demand from the automotive industry, due to legislation regulating greenhouse gas emissions, e.g., CO2. Traditionally, lightweighting has been done by replacing mild steels with ultra-high strength steel. The development of micro-sandwich materials has received increasing attention due to their formability and potential for replacing steel sheets in automotive bodies. A fundamental requirement for micro-sandwich materials to gain significant market share within the automotive industry is the possibility to simulate manufacturing of components, e.g., cold forming. Thus, reliable methods for characterizing the mechanical properties of the micro-sandwich materials, and in particular their cores, are necessary. In the present work, a novel method for obtaining the out-of-plane properties of micro-sandwich cores is presented. In particular, the out-of-plane properties, i.e., transverse tension/compression and out-of-plane shear are characterized. Test tools are designed and developed for subjecting micro-sandwich specimens to the desired loading conditions and digital image correlation is used to qualitatively analyze displacement fields and fracture of the core. A variation of the response from the material tests is observed, analyzed using statistical methods, i.e., the Weibull distribution. It is found that the suggested method produces reliable and repeatable results, providing a better understanding of micro-sandwich materials. The results produced in the present work may be used as input data for constitutive models, but also for validation of numerical models.

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  • 6.
    Hammarberg, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Kajberg, Jörgen
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindkvist, Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsén, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Evaluation of Perforated Sandwich Cores for Crash ApplicationsManuscript (preprint) (Other academic)
  • 7.
    Hammarberg, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Larsson, Simon
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsén, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Modelling of interaction between suspension and structure in a tumbling mill2014In: 11th World Congress on Computational Mechanics (WCCM XI) 5th European Conference on Computational Mechanics (ECCM V) 6th European Conference on Computational Fluid Dynamics (ECFD VI) / [ed] Eugenio Oñate; Xavier Oliver; Antonio Huerta, Barcelona, 2014, Vol. 6, p. 7383-7393Conference paper (Refereed)
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  • 8.
    Hammarberg, Samuel
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Larsson, Simon
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Kajberg, Jörgen
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsén, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Numerical evaluation of lightweight ultra high strength steel sandwich for energy absorption2020In: SN Applied Sciences, ISSN 2523-3963, E-ISSN 2523-3971, Vol. 2, no 11, article id 1876Article in journal (Refereed)
    Abstract [en]

    Legislation regarding greenhouse gas emissions forces automotive manufacturers to bring forth new and innovative materials and structures for weight reduction of the body-in-white. The present work evaluates a lightweight ultra high strength steel sandwich concept, with perforated cores, for energy absorption applications. Hat-profile geometries, subjected to crushing, are studied numerically to evaluate specific energy absorption for the sandwich concept and solid hat-profiles of equivalent weight. Precise discretization of the perforated core requires large computational power. In the present work, this is addressed by homogenization, replacing the perforated core with a homogeneous material with equivalent mechanical properties. Input data for the equivalent material is obtained by analyzing a representative volume element, subjected to in-plane loading and out-of-plane bending/twisting using periodic boundary conditions. The homogenized sandwich reduces the number of finite elements and thereby computational time with approximately 95%, while maintaining accuracy with respect to force–displacement response and energy absorption. It is found that specific energy absorption is increased with 8–17%, when comparing solid and sandwich hat profiles of equivalent weight, and that a weight saving of at least 6% is possible for equivalent performance.

  • 9.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Hammarberg, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Lindkvist, Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Preliminary validation of a new way to model physical interactions between pulp, charge and mill structure in tumbling mills2019In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 130, p. 76-84Article in journal (Refereed)
    Abstract [en]

    Modelling of wet grinding in tumbling mills is an interesting challenge. A key factor is that the pulp fluid and its simultaneous interactions with both the charge and the mill structure have to be handled in a computationally efficient way. In this work, the pulp fluid is modelled with a Lagrange based method based on the particle finite element method (PFEM) that gives the opportunity to model free surface flow. This method gives robustness and stability to the fluid model and is efficient as it gives possibility to use larger time steps. The PFEM solver can be coupled to other solvers as in this case both the finite element method (FEM) solver for the mill structure and the DEM solver for the ball charge. The combined PFEM-DEM-FEM model presented here can predict charge motion and responses from the mill structure, as well as the pulp liquid flow and pressure. All cases presented here are numerically modelled and validated against experimentally measured driving torque signatures from an instrumented small-scale batch ball mill equipped with a torque meter and charge movements captured from high-speed video. Numerical results are in good agreement with experimental torque measurements and the PFEM solver also improves on efficiency and robustness for solving charge movements in wet tumbling mill systems.

  • 10.
    Jonsén, Pär
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Larsson, Simon
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Hammarberg, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Lindkvist, Göran
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    A Particle Based Modelling Approach for Predicting Charge Dynamics in Tumbling Ball Mills2018In: ABSTRACTS: 13th World Congress on Computational Mechanics, IACM , 2018, p. 1385-1385Conference paper (Refereed)
    Abstract [en]

    Wet grinding of minerals in tumbling mills is a highly important process in the mining industry. During grinding in tumbling mills, lifters submerge into the charge and create motions in the ball charge, the lifters is exposed for impacts and shear loads that will wear down the lifters. Increased loading can accelerate the wear and the lining has to be replaced. Replacing the lining is an expensive and time consuming operation that is preferred to be done within planned maintenance stops. Prediction of the charge motion and wear rate for different grinding operations and linings are therefore desirable to predict the lining life.

     

    Modelling of wet grinding in tumbling mills that include pulp fluid and its interaction with both the grinding balls and the mill structure is an interesting challenge and some different approaches have been suggested, see [1-2]. For an effective and successful prediction, the numerical model has to be able to handle the pulp fluid and its simultaneous interactions with both the ball charge and the mill structure, in a computationally efficient approach. In this work, the pulp fluids are modelled with a Lagrange based method called incompressible computational fluid dynamics, (ICFD), which gives the opportunity to model free surface flow. This method gives robustness and stability to the fluid model and is efficient as it gives possibility to use larger time steps than the conventional CFD. The ICFD solver can be coupled to other solvers as in this case the finite element method, (FEM) solver for the mill structure and the discrete element method (DEM) solver for the ball charge. The combined ICFD-DEM-FEM model can predict both charge motion and responses from the mill structure, as well as the pulp liquid flow and pressure. The numerical grinding case presented here is validated against experimentally measured driving torque signatures from an instrumented small-scale batch ball mill, see [3]. This approach opens up the possible to predict the volume of the high-energy zone and optimise lifter design and operating conditions. The ICFD solver improve efficiency and robustness for studying wet grinding in tumbling mill systems and can predict the charge dynamics and the wear distribution in such systems.

     

    References

    [1]   Jonsén, P. et al., (2018). Preliminary validation of a new way to model physical interactions between pulp, charge and mill structure in tumbling mills. Minerals Enginering. Accepted for publication

    [2]   Jonsén, P., Stener, J.F., Pålsson, B.I. and Häggblad, H.-Å., (2015). Validation of a model for physical interactions between pulp, charge and mill structure in tumbling mills. Minerals Engineering, Vol. 73, 77–84.

    [3]   Jonsén, P. Stener, J. F. Pålsson, B. I. and Häggblad, H.-Å., (2013). Validation of tumbling mill charge induced torque as predicted by simulations. Minerals and Metallurgical Processing, vol. 30, No. 4, 220-225.

  • 11.
    Sandin, Olle
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Hammarberg, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Larour, Patrick
    voestalpine Stahl GmbH, Linz, Austria.
    Hinterdorfer, Josef
    voestalpine Stahl GmbH, Linz, Austria.
    Parareda, Sergi
    Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Plaça de la Ciència, 2, Manresa 08243, Spain.
    Frómeta, David
    Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Plaça de la Ciència, 2, Manresa 08243, Spain.
    Jonsén, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Casellas, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics. Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Plaça de la Ciència, 2, Manresa 08243, Spain.
    A numerical approach for predicting cut edge morphology in high strength sheetsManuscript (preprint) (Other academic)
  • 12.
    Sandin, Olle
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Hammarberg, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Parareda, S.
    Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Plaça de la Ciència, 2, Manresa 08243, Spain.
    Frómeta, D.
    Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Plaça de la Ciència, 2, Manresa 08243, Spain.
    Casellas, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics. Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Plaça de la Ciència, 2, Manresa 08243, Spain.
    Jonsén, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Prediction of sheared edge characteristics of advanced high strength steel2022In: IOP Conference Series: Materials Science and Engineering / [ed] Sandrine Thuillier, Vincent Grolleau, Hervé Laurent, Institute of Physics (IOP), 2022, Vol. 1238, article id 012034Conference paper (Refereed)
    Abstract [en]

    In the present work, numerical models are developed for the shearing and cutting process of advanced high strength steel-blanks which can predict the edge morphology in the shear effected zone. A damage model, based on the modified Mohr-Coulomb fracture surface, is calibrated. To increase the predictability of the numerical models, the fracture surface is fine-tuned in areas corresponding to the stress-state of cutting, a methodology called Local calibration of Fracture Surface (LCFS). Four cutting cases with varying clearance are simulated and verified with experimental tests, showing good agreement. It is thus found that the suggested methodology can simulate cutting with adequate accuracy. Furthermore, it is found that solely using plane-stress tensile specimens for calibrating the fracture surface is not enough to obtain numerical models with adequate accuracy.

  • 13.
    Sandin, Olle
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Hammarberg, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Parareda, S.
    Unit of Metallic and Ceramic Materials, Eurecat, Centre Tecnològic de Catalunya, Manresa, Spain.
    Frómeta, D.
    Unit of Metallic and Ceramic Materials, Eurecat, Centre Tecnològic de Catalunya, Manresa, Spain.
    Jonsén, Pär
    Unit of Metallic and Ceramic Materials, Eurecat, Centre Tecnològic de Catalunya, Manresa, Spain.
    Casellas, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics. Unit of Metallic and Ceramic Materials, Eurecat, Centre Tecnològic de Catalunya, Manresa, Spain.
    Numerical Modelling of Shear Cutting in High Strength Sheets2022In: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå tekniska universitet, 2022Conference paper (Refereed)
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  • 14.
    Sandin, Olle
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Rodriguez, Juan Manuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics. School of Applied Sciences and Engineering, EAFIT University, Carrera 49 No. 7 South-50, Medellín, Colombia.
    Larour, Patrick
    voestalpine Stahl GmbH, voestalpine-Straße 3, 4020, Linz, Austria.
    Parareda, Sergi
    Unit of Metallic and Ceramic Materials, Eurecat, Centre Tecnològic de Catalunya, Plaça de la Ciència, 2, 08243, Manresa, Spain.
    Frómeta, David
    Unit of Metallic and Ceramic Materials, Eurecat, Centre Tecnològic de Catalunya, Plaça de la Ciència, 2, 08243, Manresa, Spain.
    Hammarberg, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Kajberg, Jörgen
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Casellas, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics. Unit of Metallic and Ceramic Materials, Eurecat, Centre Tecnològic de Catalunya, Plaça de la Ciència, 2, 08243 Manresa, Spain.
    A particle finite element method approach to model shear cutting of high-strength steel sheets2024In: Computational Particle Mechanics, ISSN 2196-4378Article in journal (Refereed)
  • 15.
    Sandin, Olle
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Rodriguez Prieto, Juan Manuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics. School of Applied Sciences and Engineering, EAFIT University, Medellin, Colombia.
    Hammarberg, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics.
    Casellas, Daniel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Solid Mechanics. Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Manresa, Spain .
    Numerical modelling of shear cutting using particle methods2023In: IOP Conference Series: Materials Science and Engineering / [ed] Nader Asnafi, Lars-Erik Lindgren, Institute of Physics (IOP), 2023, Vol. 1284, article id 012048Conference paper (Refereed)
    Abstract [en]

    The use of Advanced High Strength Steel (AHSS) allows for lightweighting of sheet steel components, with maintained structural integrity of the part. However, AHSS grades show limitations in edge crack resistance, primarily influenced by sheared edge damage introduced by the shear cutting process. Numerical modelling of the shear cutting process can aid the understanding of the sheared edge damage, thus avoiding unforeseen edge cracking in the subsequent cold forming. However, the extreme deformations of the blank during the shear cutting process are likely to cause numerical instabilities and divergence using conventional Finite Element modelling. To overcome these challenges, this work presents the use of a particle-based numerical modelling method called the Particle Finite Element Method (PFEM). PFEM accurately solves some of the challenges encountered in shear cutting with the standard Finite Element method, such as large deformation, angular distortions, generation of new boundaries and presents an efficient way of transfer historical information from the old to the new mesh, minimising the results diffusion. The present work shows prediction of cut edge morphology of AHSS using a PFEM modelling scheme, where the numerical results are verified against experiments. With these results, the authors show new possibilities to obtain accurate numerical prediction of the shear cutting process, which promotes further advances in prediction of edge damaged related to shear cutting of AHSS.

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  • 16.
    Suarez, Laura
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Jonsén, Pär
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Hammarberg, Samuel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    A combined modeling approach to capture the physical interactions between pulp, charge and structure in a tumbling2019Conference paper (Refereed)
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