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  • 101.
    Larsson, Simon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Nishida, Masahiro
    Nagoya Institute of Technology.
    Kurano, Shuhei
    Nagoya Institute of Technology.
    Moroe, Tomoki
    Nagoya Institute of Technology.
    Gustafsson, Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Häggblad, Hans-Åke
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Modelling and characterisation of the high-rate behaviour of rock material2018Ingår i: EPJ Web of Conferences: DYMAT 2018 - 12th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, 2018, Vol. 183, artikel-id 01040Konferensbidrag (Refereegranskat)
    Abstract [en]

    For future reliable numerical simulations of impact wear on steel structures caused by rock material, knowledge about the dynamic mechanical properties of rock material is required. This paper describes the experimental and numerical work to investigate the dynamic mechanical properties of diabase (dolerite), a subvolcanic rock material. In this study, diabase from southern Sweden was used. The impact compressive strength of diabase with a density of 2.63 g/cm3 was examined by using the split-Hopkinson pressure bar (Kolsky bar) method. Cylindrical specimens were used, with a diameter of 8.9 mm and a length of 14 mm. To characterise the rock material, uniaxial compression tests were performed, at high strain rates (150 s-1). Using an inverse modelling approach, material parameters for an elastic constitutive model, with a stress-based fracture criterion were determined. The constitutive model was used in a finite element simulation of a high strain rate uniaxial compression test. Results obtained from the numerical model were in line with the experimental results.

  • 102.
    Larsson, Simon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Pålsson, Bertil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Parian, Mehdi
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    A novel approach for modelling of physical interactions between slurry, grinding media and mill structure in wet stirred media mills2020Ingår i: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 148, artikel-id 106180Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wet comminution is an important process in the mineral processing industry. Modelling of wet comminution in stirred media mills requires the simultaneous modelling of grinding media, a moving internal stirrer, and slurry. In the present study, a novel approach for modelling the physical interactions between slurry, grinding media and mill structure in a stirred media mill is presented. The slurry is modelled with the particle finite element method (PFEM). The grinding media is modelled using the discrete element method (DEM) and the mill structure is modelled using the finite element method (FEM). The interactions between slurry, grinding media and mill structure are modelled by two-way couplings between the PFEM, the DEM and the FEM models. The coupled model of the present study is used to predict the motion of slurry and grinding media, and to calculate the power draw during wet comminution in a pilot scale horizontal stirred media mill. Furthermore, the model is used to compare a Newtonian and a non-Newtonian model of the slurry, where the non-Newtonian model is used to capture experimentally observed shear-thinning. The coupled PFEM-DEM-FEM model preserves the robustness and efficiency of each of the methods and it gives the possibility to use large time increments for the fluid, greatly reducing the computational expense. The coupled model of the present work provide information on the complex dynamics of slurry and grinding media. The numerical model is shown to be a useful tool for increasing the knowledge and understanding of wet comminution in stirred media mills.

  • 103.
    Larsson, Simon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Pålsson, Bertil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Parian, Mehdi
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Particle Methods for Modelling Stirred Media Mills2019Konferensbidrag (Refereegranskat)
  • 104.
    Larsson, Simon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Pålsson, Bertil
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Parian, Mehdi
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Preliminary validation of a stirred media mill model2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Wet fine grinding is an important process in the minerals industry. Modelling of wet grinding in stirred media mills is challenging since it requires the simultaneous modelling of grinding media consisting of a huge number of small grinding bodies, moving internal stirrer, and the pulp fluid. All of them in interaction with each other. In the present study, wet grinding in a stirred media mill is studied using coupled incompressible computational fluid dynamics (ICFD) and discrete element method (DEM) and finite element method (FEM) simulations. The DEM is used to model the grinding media, and the pulp fluid flow is modelled using the ICFD. Moreover, the FEM is used to model the structure of the mill body and is in combination with DEM used to estimate the wear rate in the system. The present implementation of the coupled ICFD-DEM-FEM preserves the robustness and efficiency of both methods, and it gives the possibility to use large time steps for the fluid with very low computation times.

  • 105.
    Larsson, Simon
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Rodriguez Prieto, Juan Manuel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Gustafsson, Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Häggblad, Hans-Åke
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    The particle finite element method for transient granular material flow: modelling and validation2020Ingår i: Computational Particle Mechanics, ISSN 2196-4378Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The prediction of transient granular material flow is of fundamental industrial importance. The potential of using numerical methods in system design for increasing the operating efficiency of industrial processes involving granular material flow is huge. In the present study, a numerical tool for modelling dense transient granular material flow is presented and validated against experiments. The granular materials are modelled as continuous materials using two different constitutive models. The choice of constitutive models is made with the aim to predict the mechanical behaviour of a granular material during the transition from stationary to flowing and back to stationary state. The particle finite element method (PFEM) is employed as a numerical tool to simulate the transient granular material flow. Use of the PFEM enables a robust treatment of large deformations and free surfaces. The fundamental problem of collapsing rectangular columns of granular material is studied experimentally employing a novel approach for in-plane velocity measurements by digital image correlation. The proposed numerical model is used to simulate the experimentally studied column collapses. The model prediction of the in-plane velocity field during the collapse agrees well with experiments.

  • 106. Lindkvist, Göran
    et al.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    TV-holography for strain field measurements on green powder compacts subjected to in-plane loading2007Ingår i: Proceedings: PM in Toulouse - at the forefront of european technology; 15 - 17 October 2007, Pierre Baudis Congress Centre, Toulouse, France, Shrewsbury: European powder metallurgy association , 2007, Vol. 3 : Powder pressing : sintering ; full density & alternative consolidation ; modelling ; secondary & finishing operations, s. 361-366Konferensbidrag (Refereegranskat)
    Abstract [en]

    Numerical modelling, for example FE-analysis, of powder processes requires detailed material data from physical experiments. This work intends to show possibilities to retrieve such data by TV-holography. A small disc of pressed metal powder is subjected to diametral loading. In-plane displacement field information is measured by the change in interference pattern of two laser beams diffusively reflected on the powder disc surface. Strain fields can be obtained by numerical differentiation. Findings show that non-linear elastic behaviour in the material can be detected.

  • 107.
    Neikter, Magnus
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Forsberg, Fredrik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Pederson, Robert
    Department of Engineering Science, University West.
    Antti, Marta-Lena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Åkerfeldt, Pia
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Larsson, Simon
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Puyoo, Geraldine
    GKN-Aerospace Engine Systems.
    Defect characterization of electron beam melted Ti-6Al-4V and Alloy 718 with X-ray microtomography2018Ingår i: Aeronautics and Aerospace Open Access Journal, ISSN 2576-4500, Vol. 2, nr 3, s. 139-145Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electron beam melting (EBM) is emerging as a promising manufacturing process where metallic components are manufactured from three-dimensional (3D) computer aided design models by melting layers onto layers. There are several advantages with this manufacturing process such as near net shaping, reduced lead times and the possibility to decrease weight by topology optimization, aspects that are of interest for the aerospace industry. In this work two alloys, Ti-6Al-4V and Alloy 718, widely used within the aerospace industry were investigated with X-ray microtomography (XMT), to characterize defects such as lack of fusion (LOF) and inclusions. It was furthermore possible to view the macrostructure with XMT, which was compared to macrostructure images obtained by light optical microscopy (LOM). XMT proved to be a useful tool for defect characterization and both LOF and un-melted powder could be found in the two investigated samples. In the EBM built Ti-6Al-4V sample high density inclusions, believed to be composed of tungsten, were found. One of the high-density inclusions was found to be hollow, which indicate that the inclusion stems from the powder manufacturing process and not related with the EBM process. By performing defect analyses with the XMT software it was also possible to quantify the amount of LOF and un-melted powder in vol%. From the XMT-data meshes were produced so that finite element method (FEM) simulations could be performed. From these FEM simulations the significant impact of defects on the material properties was evident, as the defects led to high stress concentrations. It could moreover, with FEM, be shown that the as-built surface roughness of EBM material is of importance as high surface roughness led to increased stress concentrations.

  • 108.
    Nishida, Masahiro
    et al.
    Nagoya Institute of Technology.
    Ito, Yoshitaka
    Nagoya Institute of Technology.
    Gustafsson, Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Häggblad, Hans-Åke
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Takayama, T.
    Yamagata University.
    Todo, M.
    Kyushu University.
    Determination of dynamic material properties for poly(L-lactic acid)/poly(e-caprolactone) blends: Experiments and simulation using split Hopkinson pressure bars2012Ingår i: EPJ Web of Conferences: DYMAT 2012 - 10th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading / [ed] S. Hiermaier, Les Ulis: EDP Sciences, 2012, Vol. 26, s. 3001-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Coefficients of Cowper-Symonds constitutive equation for PLLA/PCL = 80/20 were determined using the results of compressive tests at high and low strain rates. The simulation of split Hopkinson pressure bar using the coefficients was carried out under the same condition as the experiments. The diameter and thickness of specimens were measured by a high-speed video camera. The stress and strain histories of specimens, the thickness and the diameter in the simulations at high strain rate were compared with those in the experiments

  • 109.
    Nishida, Masahiro
    et al.
    Nagoya Institute of Technology.
    Kato, Hidinori
    Nagoya Institute of Technology.
    Häggblad, Hans-Åke
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Gustafsson, Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Strain rate effects on constitutive properties of high velocity pressed iron powder2012Konferensbidrag (Refereegranskat)
  • 110.
    Nishida, Masahiro
    et al.
    Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Japan, Nagoya Institute of Technology.
    Kuroyanagi, Yuki
    Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Japan.
    Häggblad, Hans-åke
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Gustafsson, Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Strain rate effects on tensile strength of iron green bodies2015Ingår i: EPJ Web of Conferences, ISSN 2101-6275, E-ISSN 2100-014X, Vol. 94, artikel-id 1069Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Impact tensile strength of iron green bodies with densities of 7.2 and 7.4 g/cm3 was examined by Brazilian test using the split-Hopkinson pressure bar (Kolsky bar) method. The powder material used for the experiments was a press-ready premix containing Distaloy AE, graphite, and lubricant. During dynamic compression, the failure behavior of specimens was observed using a high-speed video camera. The failure stress and failure behavior of dynamic compressive tests were compared with those of static compressive tests.

  • 111.
    Nishida, Masahiro
    et al.
    Nagoya Institute of Technology.
    Ogura, Takashi
    Nagoya Institute of Technology.
    Kato, Hidinori
    Nagoya Institute of Technology.
    Häggblad, Hans-Åke
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Gustafsson, Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Compressive Properties of High Velocity Pressed Iron Powder at High Strain Rates2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the field of powder metallurgy, high velocity compaction (HVC) is a production technique with capacity to improve the mechanical properties of powder metallurgy parts because high density of powder metallurgy parts can be achieved in less than 0.5 s [1, 2]. In order to extend the usage of the HVC method, detailed knowledge of the HVC process is important. To facilitate development of production processes, numerical simulations can be utilized. A common numerical method for powder compaction is the finite element method (FEM). To conduct on FEM simulation precisely, constitutive data of HVC specimens at high strain-rate are required [3, 4]. In this study, the dynamic compressive properties of cylindrical specimens made by HVC were measured using a Spit Hopkinson Pressure Bar (Kolsky bar). The powder material used for the experiments was a press-ready premix containing Distaloy AE, 0.5% graphite (uf-4) and 0.6% Kenolube. During dynamic compression, the failure behavior of specimens was also observed using a high speed video camera. The experimental results, such as failure stress, Young’s modulus and failure behavior, of dynamic compressive tests were compared with those of static compressive tests. Among specimens made by HVC and Conventional Compaction (CC), the effects of specimen density, 6.9, 7.2 and 7.4 g/cm3, on the compressive properties and failure behavior were also examined. For each density, the difference in the failure behavior between HVC-pressed specimens and conventional pressed specimens was observed, whereas stress-strain curves of HVC-pressed specimens were the same as conventional pressed specimens. Moreover, the effects of specimen size on failure behavior and stress-strain curves of specimens were examined.

  • 112.
    Nishida, Masahiro
    et al.
    Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Japan.
    Yamaguchi, M
    Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Japan.
    Todo, M
    Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka, Japan.
    Takayama, T
    Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka, Japan.
    Häggblad, Hans-Åke
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Evaluation of dynamic compressive properties of PLA polymer blends using split Hopkinson pressure bar2009Ingår i: DYMAT 2009, 9th International conferense on the mechanical and physical behaviour of materials under dynamic loading: Experimental techniques, Industrial applications, Bio-Mechanics, Les Ulis: EDP Sciences, 2009, Vol. 1, s. 909-915Konferensbidrag (Refereegranskat)
    Abstract [en]

    Poly(lactic acid) (PLA) has been used as a biomaterial for bone fixation devices in oral and orthopedic surgery because of good biocompatibility and bioabsorbability. Because Poly(e-Caprolactone) (PCL) is a ductile, bioabsorbable and biodegradable polymer, many types of PLA/ PCL polymer blends have been developed to improve its material strength and impact resistance. The stress-strain curves of PLA and PLA/PCL polymer blends were measured using a split Hopkinson pressure bar (Kolsky bar) method and a universal testing machine. The effect of PCL content on Young's modulus and yield stress was examined. The values of constants in Cowper-Symonds equation with respect to yield stress were determined for PLA and PLA/PCL polymer blend specimens. PLA/PCL specimens were observed using a scanning electron microscope.

  • 113.
    Ramanenka, Dmitrij
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Antti, Marta-Lena
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Gustafsson, Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Characterization of high-alumina refractory bricks and modelling of hot rotary kiln behaviour2017Ingår i: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 79, s. 852-864Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rotary kilns for iron-ore pellets production are highly dependent on a well-functioning refractory brick lining. To improve the long-term capability of the lining, in-situ observations of the bricks' performance are desired, however, the high process temperatures and the size of the kiln make it difficult to study the lining during operation. By using numerical simulations as a tool, some of the problems encountered by the brick lining can be studied. Knowing material properties of the refractory bricks as input in a numerical model is therefore necessary. However, material properties are poorly documented for this type of materials, especially, at elevated temperatures. In this work three commercial aluminasilicate bricks were tested in compression until failure for a temperature range of 25–1300 °C. The purpose was to evaluate compression strength and Young's modulus in compression of the fully burned bricks at a wide range of temperatures. The data was later used for modelling of a hot rotary kiln lined with bricks by using the finite element method, whereupon load state of the lining was evaluated at steady state after the expansion of the system. The objective of the numerical modelling was to investigate trustworthiness of the model and to give insight into the stress levels that can potentially arise. It was found that for all of the investigated brick types the compression strength increased with increased temperature, having a peak in the vicinity of 1000 °C. The maximum increase was between 50 and 150 % for the different brick types. After passing 1100 °C the compression strength rapidly and considerably decreased below its as-received compression strength. Young's modulus was measured to vary between 2 and 10 GPa in the range of up to 1000 °C. The numerical results indicate that severe boundary conditions (expansion of the lining is highly restricted) can potentially lead to compression stress of up to 34 MPa in the brick lining at steady state. However, at these boundary conditions the present tensile stress was only 0.5 MPa, while tensile stresses of close to 3 MPa could be observed in the lining with mild boundary conditions. The authors conclude that the created model is trustworthy and that it has high potential for being used as a tool in further investigations of the lining in hot state.

  • 114.
    Ramanenka, Dmitrij
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Gustafsson, Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Influence of heating and cooling rate on the stress state of the brick lining in a rotary kiln using finite element simulations2019Ingår i: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 105, s. 98-109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rotary kilns for iron-ore pellets production are highly dependent on a well-functioned refractory brick lining. To improve the long-term capability of the lining, in-situ observations of the bricks' performance are desired, however, the harsh environment inside the rotary kiln makes it difficult or nearly impossible to study the lining during operation. By using numerical simulations as a tool, some of the problems encountered by the brick lining can be studied without limitation of the extreme conditions.

    In this work, stress state of the lining was studied under the influence of different heating and cooling rates, and different brick compaction cases. A finite element model was created for conducting the numerical simulations. The numerical model was calibrated for transient heat transfer. Temperature dependent material properties of the bricks and casing were used as input. The heating and cooling was controlled by temperature prescription on the boundary of the brick lining, while brick lining compaction by defining relative position of the bricks in axial and radial directions.

    The conducted numerical simulations showed that considerable tensile stress may appear in a large area of the brick during initial heating stage. The large tensile area corresponds well with the typical circumferential cracks experienced by the bricks. It was demonstrated that the compressive stresses counteract the development of tensile stresses. However, the compressive stresses may become very large in the initial stage of heating. The positive effect of lower heating rate was considerable on the tensile stresses, while influence on the compressive stresses was almost unnoticed. The hypothetical cooling rates showed that very high tensile stresses may occur on the surface of the bricks, potentially leading to surface spalling. Furthermore, it was demonstrated that axial compaction is highly important on the stress development in the lining, which, may not always be followed in practice. As a general conclusion, it is recommended to always achieve a tight compaction of the brick lining and to take measures for lowering the heating and cooling rates.

    The conducted work exemplifies behaviour of the brick lining for realistic heat transfer and material properties. The insight into the behaviour gives possibilities to make adjustments and directed investments for lowering risk of brick lining failure.

  • 115.
    Ramanenka, Dmitrij
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Gustafsson, Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Modelling of Hot Rotary Kiln2017Konferensbidrag (Refereegranskat)
  • 116.
    Ramanenka, Dmitrij
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Gustafsson, Gustaf
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Nordin, Lars Olof
    Loussavaara-Kiirunavaara Limited, Luleå.
    Evaluation of stress state in a brick lining of a hot rotary kiln due to material and design change2017Ingår i: Proceedings of the World Congress on Mechanical, Chemical, and Material Engineering, Avestia Publishing, 2017Konferensbidrag (Refereegranskat)
  • 117.
    Ramanenka, Dmitrij
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Stjernberg, Jesper
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik.
    Eriksson, Kjell
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Modelling of refractory brick furniture in rotary-kiln using finite element approach2014Ingår i: 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: International Center for Numerical Methods in Engineering (CIMNE), 2014, Vol. 2, s. 1199-1210Konferensbidrag (Refereegranskat)
  • 118.
    Ramanenka, Dmitrij
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Stjernberg, Jesper
    Loussavaara-Kiirunavaara Limited, Lulea.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    FEM investigation of global mechanisms affecting brick lining stability in a rotary kiln in cold state2016Ingår i: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 59, s. 554-569Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Severe degradation of refractory lining in a rotary kiln often leads to very costly production delays. Use of finite element analysis for understanding the mechanisms behind the failure of the lining is poorly reported in this field. To increase the knowledge and to update the field a simplified model of a kiln and a new methodology for studying stability of the lining are suggested. Behaviour of the lining in cold state – in static and dynamic cases – is studied. Influence of ovality, brick's Young's modulus and friction coefficient on stress and brick displacement are evaluated at two rotational speeds. It was found that the induced loads in the lining are harmless regardless of the tested conditions — challenging the traditional beliefs. On the other hand, recorded brick displacements were found to be significantly affected by rotational speed and ovality. Gaps as large as 80 mm could be observed between the bricks and the casing in a worst case scenario. An integrity coefficient was defined in order to quantify overall integrity of the lining.

  • 119.
    Rodriguez, Juan Manuel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Svoboda, Ales
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    A particle finite element method applied to modeling and simulation of machining processes2017Ingår i: Advanced Machining Processes: Innovative Modeling Techniques / [ed] Angelos P. Markopoulos, J. Paulo Davim, Boca Raton: CRC Press, 2017, 1 ed, s. 1-24Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Metal cutting process is a nonlinear dynamic problem that includesgeometrical, material, and contact nonlinearities. In this work, aLagrangian finite element approach for the simulation of metal cuttingprocess is presented based on the so-called particle finite element method(PFEM). The governing equations for the deformable bodies are discretizedwith the finite element method (FEM) via a mixed formulationusing simplicial elements with equal linear interpolation for displacements,pressure, and temperature. The use of PFEM for modeling ofmetal cutting processes includes the use of a remeshing process, α-shapeconcepts for detecting domain boundaries, contact mechanics laws, andmaterial constitutive models. In this chapter, a 2D PFEM-based numericalmodeling of metal cutting processes has been studied to investigate theeffects of cutting velocity on tool forces, temperatures, and stresses inmachining of Ti–6Al–4V. The Johnson–Cook plasticity model is usedto describe the work material behavior. Numerical simulations are inagreement with experimental results.

  • 120.
    Rodriguez, Juan Manuel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Svoboda, Ales
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Dislocation Density Based Material Model Applied in PFEM-simulation of Metal Cutting2017Ingår i: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 58, s. 193-197Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Metal cutting is one of the most common metal-shaping processes. In this process, specified geometrical and surface properties are obtained through the break-up and removal of material by a cutting edge into a chip. The chip formation is associated with large strains, high strain rates and locally high temperatures due to adiabatic heating. These phenomena together with numerical complications make modeling of metal cutting challenging. Material models, which are crucial in metal-cutting simulations, are usually calibrated against data from material testing. Nevertheless, the magnitudes of strains and strain rates involved in metal cutting are several orders of magnitude higher than those generated from conventional material testing. Therefore, a highly desirable feature is a material model that can be extrapolated outside the calibration range. In this study, a physically based plasticity model based on dislocation density and vacancy concentration is used to simulate orthogonal metal cutting of AISI 316L. The material model is implemented into an in-house particle finite-element method software. Numerical simulations are in agreement with experimental results for different cutting speed and feed.

  • 121.
    Rodriguez Prieto, J. M.
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Carbonell, J. M.
    International Center for Numerical Methods in Engineering (CIMNE), Barcelona, Spain.
    Cante, J.C.
    Escola Tècnica Superior d’Enginyeries Industrial i Aeronàutica de Terrassa; International Center for Numerical Methods in Engineering (CIMNE), Barcelona, Spain.
    Oliver, J.
    E.T.S dEnginyers de Camins, Canals i Ports, Technical University of Catalonia (BarcelonaTech), Barcelona, Spain. International Center for Numerical Methods in Engineering (CIMNE), Barcelona, Spain.
    Jonsén, P.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Generation of segmental chips in metal cutting modeled with the PFEM2018Ingår i: Computational Mechanics, ISSN 0178-7675, E-ISSN 1432-0924, Vol. 61, nr 6, s. 639-655Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Particle Finite Element Method, a lagrangian finite element method based on a continuous Delaunay re-triangulation of the domain, is used to study machining of Ti6Al4V. In this work the method is revised and applied to study the influence of the cutting speed on the cutting force and the chip formation process. A parametric methodology for the detection and treatment of the rigid tool contact is presented. The adaptive insertion and removal of particles are developed and employed in order to sidestep the difficulties associated with mesh distortion, shear localization as well as for resolving the fine-scale features of the solution. The performance of PFEM is studied with a set of different two-dimensional orthogonal cutting tests. It is shown that, despite its Lagrangian nature, the proposed combined finite element-particle method is well suited for large deformation metal cutting problems with continuous chip and serrated chip formation.

  • 122.
    Rodriguez Prieto, Juan Manuel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Carbonell, J.M
    International Center for Numerical Methods in Engineering (CIMNE), Campus Nord UPC, Barcelona, Spain.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Numerical Methods for the Modelling of Chip Formation2019Ingår i: Archives of Computational Methods in Engineering, ISSN 1134-3060, E-ISSN 1886-1784Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The modeling of metal cutting has proved to be particularly complex due to the diversity of physical phenomena involved, including thermo-mechanical coupling, contact/friction and material failure. During the last few decades, there has been significant progress in the development of numerical methods for modeling machining operations. Furthermore, the most relevant techniques have been implemented in the relevant commercial codes creating tools for the engineers working in the design of processes and cutting devices. This paper presents a review on the numerical modeling methods and techniques used for the simulation of machining processes. The main purpose is to identify the strengths and weaknesses of each method and strategy developed up-to-now. Moreover the review covers the classical Finite Element Method covering mesh-less methods, particle-based methods and different possibilities of Eulerian and Lagrangian approaches.

  • 123.
    Rodriguez Prieto, Juan Manuel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Svoboda, Ales
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    A Particle Finite Element Method for Machining Simulations2016Ingår i: ECCOMAS Congress 2016: VII European Congress on Computational Methods in Applied Sciences and Engineering, Crete Island, Greece, 5–10 June 2016 / [ed] M. Papadrakakis; V. Papadopoulos; G. Stefanou; V. Plevris, Athens: National Technical University of Athens , 2016, Vol. 1, s. 539-553Konferensbidrag (Refereegranskat)
    Abstract [en]

    Metal cutting process is a nonlinear dynamic problem that includes geometrical, material, and contact nonlinearities. In this work a Lagrangian finite element approach for simulation of metal cutting processes is presented, based on the so-called Particle Finite Ele-ment Method (PFEM). The governing equations for the deformable bodies are discretized with the FEM via a mixed formulation using simplicial elements with equal linear interpolation for displacements, pressure and temperature. The use of PFEM for modeling of metal cutting pro-cesses includes the use of a remeshing process, α -shape concepts for detecting domain bound-aries, contact mechanics laws and material constitutive models. The merits of the formulation are demonstrated in the solution of 2D and 3D thermally-coupled metal cutting processes using the particle finite element method. The method shows good results and is a promising method for future simulations of thermally/coupled machining processes.

  • 124.
    Rodriguez Prieto, Juan Manuel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Svoboda, Ales
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Numerical modeling of metal cutting processes using the particle finite element method (PFEM) and a physically based plasticity model2015Ingår i: Particle-based Methods IV: Fundamentals and Applications : Proceedings of the IVInternational Conference on Particle-Based Methods–Fundamentals and Applications held in Barcelona, Spain, 28-30September 2015 / [ed] E. Oñate; M. Bischoff; D.R.J. Owen; P. Wriggers; T. Zhodi, Barcelona: International Center for Numerical Methods in Engineering (CIMNE), 2015, s. 1066-1072Konferensbidrag (Refereegranskat)
    Abstract [en]

    Metal cutting is one of the most common metal shaping processes. Specified geometrical and surface properties are obtained by break-up of material and removal by a cutting edge into a chip. The chip formation is associated with large strain, high strain rate and locally high temperature due to adiabatic heating which make the modeling of cutting processes difficult. Furthermore, dissipative plastic and friction work generate high local temperatures. These phenomena together with numerical complications make modeling of metal cutting difficult. Material models, which are crucial in metal cutting simulations, are usually calibrated based on data from material testing. Nevertheless, the magnitude of strain and strain rate involved in metal cutting are several orders higher than those generated from conventional material testing. Therefore, a highly desirable feature is a material model that can be extrapolated outside the calibration range. In this study a physically based plasticity model based on dislocation density and vacancy concentration is used to simulate orthogonal metal cutting of AISI 316L. The material model is implemented into an in-house Particle Finite Element Method software. Numerical simulations are in agreement with experimental results, but also with previous results obtained with the finite element method.

  • 125.
    Rodriguez Prieto, Juan Manuel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Svoboda, Ales
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    On the Numerical Modeling of Metal Forming Processes Using the Particle Finite Elementmethod2016Ingår i: Proceedings of 29th Nordic Seminar on Computational Mechanics – NSCM29 / [ed] Ragnar Larsson, Göteborg: Department of Applied Mechanics CHALMERS UNIVERSITY OF TECHNOLOGY Göteborg, Sweden 2016 , 2016, , s. 4Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work a Lagrangian nite element approach for simulation of metalforming is presented, based on the so-called Particle Finite Element Method (PFEM). Thegoverning equations for the deformable bodies are discretized with the FEM via a mixedformulation using simplicial elements with equal linear interpolation for displacements,pressure and temperature. The use of PFEM for modeling of metal forming processesincludes the use of a remeshing process, -shape concepts for detecting domain boundaries,contact mechanics laws and material constitutive models. The merits of the formulationare demonstrated in the solution of 2D thermally coupled metal forming processes usingthe particle nite element method. The method shows good results and is a promisingmethod for future simulations of thermally/coupled forming processes.

  • 126.
    Rodriguez Prieto, Juan Manuel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Svoboda, Ales
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Simulation of metal cutting using the particle finite-element method and a physically based plasticity model2017Ingår i: Computational Particle Mechanics, ISSN 2196-4378, Vol. 4, nr 1, s. 35-51Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Metal cutting is one of the most common metal-shaping processes. In this process, specified geometrical and surface properties are obtained through the break-up of material and removal by a cutting edge into a chip. The chip formation is associated with large strains, high strain rates and locally high temperatures due to adiabatic heating. These phenomena together with numerical complications make modeling of metal cutting difficult. Material models, which are crucial in metal-cutting simulations, are usually calibrated based on data from material testing. Nevertheless, the magnitudes of strains and strain rates involved in metal cutting are several orders of magnitude higher than those generated from conventional material testing. Therefore, a highly desirable feature is a material model that can be extrapolated outside the calibration range. In this study, a physically based plasticity model based on dislocation density and vacancy concentration is used to simulate orthogonal metal cutting of AISI 316L. The material model is implemented into an in-house particle finite-element method software. Numerical simulations are in agreement with experimental results, but also with previous results obtained with the finite-element method.

  • 127.
    Svoboda, Ales
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Häggblad, Hans-Åke
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Simulations of hot isostatic powder pressing for near net shaped components2014Ingår i: 11th International Conference on Hot Isostatic Pressing 2014: HIP'14 in Stockholm, Sweden 9 - 13, 2014, Stockholm: Jernkontoret , 2014, s. 80-87Konferensbidrag (Refereegranskat)
  • 128.
    Zakrisson, Björn
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Häggblad, Hans-Åke
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Jonsén, Pär
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Modelling and simulation of explosions in soil interacting with deformable structures2012Ingår i: Central European Journal of Engineering, ISSN 1896-1541, E-ISSN 2081-9927, Vol. 2, nr 4, s. 532-550Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A detonating explosive interacting with a deformable structure is a highly transient and non-linear event. In field blast trials of military vehicles, a standard procedure is often followed in order to reduce the uncertainties and increase the quality of the test. If the explosive is buried in the ground, the state of the soil must meet specific demands. In the present work, laboratory experiments have been performed to characterize the behaviour of a soil material. Soil may be considered a three-phase medium, consisting of solid grains, water and air. Variations between the amounts of these phases affect the mechanical properties of the soil. The experimental outcome has formed input data to represent the soil behaviour included in a three-phase elastic-plastic cap model. This unified constitutive model for soil has been used for numerical simulations representing field blast trials, where the explosive load is interacting with a deformable structure. The blast trials included explosive buried at different depths in wet or dry sand. A dependence of the soil initial conditions can be shown, both in the past field trials along with the numerical simulations. Even though some deviations exist, the simulations showed in general acceptable agreement with the experimental results.

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