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  • 1.
    Casellas, Daniel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära. Eurecat, Centre Tecnològic de Catalunya, Manresa, Spain.
    Frómeta, D.
    Eurecat, Centre Tecnològic de Catalunya, Manresa, Spain.
    Parareda, S.
    Eurecat, Centre Tecnològic de Catalunya, Manresa, Spain.
    Grifé, L.
    Eurecat, Centre Tecnològic de Catalunya, Manresa, Spain.
    Tarhouni, I.
    Eurecat, Centre Tecnològic de Catalunya, Manresa, Spain.
    Sandin, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    When fracture toughness becomes essential for Lightweighting: Understanding cracking behaviour in high strength sheets2022Inngår i: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå tekniska universitet, 2022Konferansepaper (Fagfellevurdert)
  • 2.
    Sandin, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Predicting Sheared Edge Characteristics of High Strength Steels2022Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    An efficient way of reducing CO2 emissions from the transportation sector is to reduce the vehicle weights, i.e. lightweighting. A common strategy for lightweighting of vehicles is to replace the steels used to build structural parts of the vehicle, usually manufactured by metallic sheets, with stronger, advanced high strength steel (AHSS) grades. Using stronger steel grades enables down-gauging while the structural integrity of the parts remain unchanged. However, the increase in strength of AHSS typically comes with a loss of ductility, affecting their forming properties. A common AHSS manufacturing defect is edge cracking occurring when a sheared edge (damaged by the shearing operation) is bent or stretched. It is known in the sheet metal forming industry that the shear cutting process introduces damage, in terms of micro-cracks and notches, to sheared edges from which edge cracks can grow. Conventional forming analyses do not include the effects from sheared edge damage and therefore can not predict edge cracking during forming. Numerical modelling of the shear cutting process can aid the understanding of sheared edge damage and how it affects the AHSS edge cracking phenomena.

    This thesis presents experimental and numerical methods for calibration of acommercial damage- and failure model, intended for shear cutting simulations. Crack initiation and propagation govern the shear cutting process of AHSS sheets. Therefore, a commercial numerical damage- and failure model was studied regarding its ability to predict shear edge damage. The investigation shows that the damage and failure model has limitations concerning prediction of crack initiation, thus concluding that modelling of processes including formation of cracks using the said damage- and failure model risks to generate erroneous results. This phenomena was also seen in modelling of shear cutting, where the crack-driven fracture process following burnish formation was delayed. Through sensitivity analysis of uncalibrated areas on the failure locus could accurate correlation between numerical and experimental cut edge morphology be obtained. Such results show that additional calibration experiments are necessary, but also the need for development of stress-state dependent failure modelling of AHSS that includes the effect from cracks.

    Fulltekst (pdf)
    fulltext
  • 3.
    Sandin, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Hammarberg, Samuel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    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 tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Casellas, Daniel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära. 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 sheetsManuskript (preprint) (Annet vitenskapelig)
  • 4.
    Sandin, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Hammarberg, Samuel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    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 tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära. Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Plaça de la Ciència, 2, Manresa 08243, Spain.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Prediction of sheared edge characteristics of advanced high strength steel2022Inngår i: IOP Conference Series: Materials Science and Engineering / [ed] Sandrine Thuillier, Vincent Grolleau, Hervé Laurent, Institute of Physics (IOP), 2022, Vol. 1238, artikkel-id 012034Konferansepaper (Fagfellevurdert)
    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.

  • 5.
    Sandin, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Hammarberg, Samuel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    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 tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära. Unit of Metallic and Ceramic Materials, Eurecat, Centre Tecnològic de Catalunya, Manresa, Spain.
    Numerical Modelling of Shear Cutting in High Strength Sheets2022Inngår i: Svenska Mekanikdagar 2022 / [ed] Pär Jonsén; Lars-Göran Westerberg; Simon Larsson; Erik Olsson, Luleå tekniska universitet, 2022Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 6.
    Sandin, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Frómeta, David
    Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Plaça de la Ciència 2, 08243 Manresa, Spain.
    Casellas, Daniel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära. Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Plaça de la Ciència 2, 08243 Manresa, Spain.
    Stating failure modelling limitations of high strength sheets: Implications to sheet metal forming2021Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 14, nr 24, artikkel-id 7821Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article discusses the fracture modelling accuracy of strain-driven ductile fracture models when introducing damage of high strength sheet steel. Numerical modelling of well-known fracture mechanical tests was conducted using a failure and damage model to control damage and fracture evolution. A thorough validation of the simulation results was conducted against results from laboratory testing. Such validations show that the damage and failure model is suited for modelling of material failure and fracture evolution of specimens without damage. However, pre-damaged specimens show less correlation as the damage and failure model over-predicts the displacement at crack initiation with an average of 28%. Consequently, the results in this article show the need for an extension of the damage and failure model that accounts for the fracture mechanisms at the crack tip. Such extension would aid in the improvement of fracture mechanical testing procedures and the modelling of high strength sheet metal manufacturing, as several sheet manufacturing processes are defined by material fracture.

  • 7.
    Sandin, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Rodriguez, Juan Manuel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära. 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 tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Kajberg, Jörgen
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Casellas, Daniel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära. 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 sheets2024Inngår i: Computational Particle Mechanics, ISSN 2196-4378Artikkel i tidsskrift (Fagfellevurdert)
  • 8.
    Sandin, Olle
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Rodriguez Prieto, Juan Manuel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära. School of Applied Sciences and Engineering, EAFIT University, Medellin, Colombia.
    Hammarberg, Samuel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära.
    Casellas, Daniel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Hållfasthetslära. Eurecat, Centre Tecnològic de Catalunya, Unit of Metallic and Ceramic Materials, Manresa, Spain .
    Numerical modelling of shear cutting using particle methods2023Inngår i: IOP Conference Series: Materials Science and Engineering / [ed] Nader Asnafi, Lars-Erik Lindgren, Institute of Physics (IOP), 2023, Vol. 1284, artikkel-id 012048Konferansepaper (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
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