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Häggblad, Hans-ÅkeORCID iD iconorcid.org/0000-0002-7514-0513
Alternative names
Publications (10 of 141) Show all publications
Larsson, S., Gustafsson, G., Jonsén, P. & Häggblad, H.-Å. (2018). DEM-CFD Simulation of the Effect of Air on Powder Flow During Die Filling. In: : . Paper presented at 13th World Congress in Computational Mechanics.
Open this publication in new window or tab >>DEM-CFD Simulation of the Effect of Air on Powder Flow During Die Filling
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

In the field of powder metallurgy (PM), complex components with complicated shapes can be manufactured. One important step in the PM process is the powder pressing process, where powder is consolidated during a forming operation into a desired shape, normally by applying pressure. During powder pressing, the mechanical properties of powder materials change dramatically. PM manufacturers tend to produce components with shapes of increasing complexity, requiring improved pressing equipment and methods. The most crucial aspect is to control the powder flow during die filling and the final powder density distribution after the filling stage, which has been shown to affect the strength of the final component significantly [1].

To investigate the non-homogeneity of the density of PM components, experimental studies combined with numerical simulations of the die filling stage are exploited.

This work covers the numerical modelling and simulation of die filling. The discrete element method (DEM) [2] was used to model the powder, and computational fluid dynamics (CFD) to model the air. To study the effect of air on powder flow, the DEM was coupled to the CFD using a two-way coupling approach. Experimental measurements with digital speckle photography (DSP) from a previous study [3] were used for comparison with the numerical simulations.

The comparison of the DSP measurements and the numerical simulations showed similar macroscopic flow characteristics. Thus, the adequacy of the proposed DEM-CFD model has been demonstrated in a metal powder die filling operation. The DEM-CFD method has been shown to be an effective method for the numerical simulation of the interaction between powder and air.

 

References

[1]   Zenger, D. & Cai, H. (1997). Handbook of the Common Cracks in Green P/M Compacts. Metal Powder Industries Federation, MPIF. Worcester, USA.

[2]   Cundall, P. A., & Strack, O. D. (1979). A discrete numerical model for granular assemblies. geotechnique, 29(1), 47-65.

[3]   Larsson, S., Gustafsson, G., Jonsén, P. & Häggblad, H.-Å. (2016). Study of Powder Filling Using Experimental and Numerical Methods.  In: World PM2016 Congress & Exhibition, Hamburg, October 9-13, 2016.

National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-71547 (URN)
Conference
13th World Congress in Computational Mechanics
Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-27
Larsson, S., Gustafsson, G., Häggblad, H.-å. & Jonsén, P. (2018). Experimental and numerical study of potassium chloride flow using smoothed particle hydrodynamics. Minerals Engineering, 116, 88-100
Open this publication in new window or tab >>Experimental and numerical study of potassium chloride flow using smoothed particle hydrodynamics
2018 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 116, p. 88-100Article in journal (Refereed) Published
Abstract [en]

Materials in granular form are widely used in industry and in the society as a whole. Granular materials can have various behaviours and properties. An accurate prediction of their flow behaviour is important to avoid handling and transportation issues. In this study, the flow behaviour of dry potassium chloride (KCl) in granular form was investigated experimentally and simulated numerically. The aim was to develop numerical tools to predict the flow of KCl in transportation and handling systems and granular material flow in various industrial applications. Two experimental setups were used to quantify the flow of KCl. In the first setup, the collapse of an axisymmetric granular column was investigated. In the second setup, digital image correlation was used to obtain velocity field measurements of KCl during the discharge of a flat-bottomed silo. The two experiments were represented numerically using two-dimensional computational domains. The smoothed particle hydrodynamics method was used for the simulations, and a pressure-dependent, elastic-plastic constitutive model was used to describe the granular materials. The numerical results were compared to the experimental observations, and an adequate qualitative and quantitative agreement was found for the granular column collapse and the silo discharge. Overall, the simulated flow patterns showed adequate agreement with the experimental results obtained in this study and with the observations reported in the literature. The experimental measurements, in combination with the numerical simulations, presented in this study adds to the knowledge of granular material flow prediction. The results of this study highlights the potential of numerical simulation as a powerful tool to increase the knowledge of granular material handling operations.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-62669 (URN)10.1016/j.mineng.2017.11.003 (DOI)000424172900012 ()
Note

Validerad;2018;Nivå 2;2018-01-25 (andbra)

Available from: 2017-03-24 Created: 2017-03-24 Last updated: 2019-03-14Bibliographically approved
Larsson, S., Nishida, M., Kurano, S., Moroe, T., Gustafsson, G., Häggblad, H.-Å. & Jonsén, P. (2018). Modelling and characterisation of the high-rate behaviour of rock material. In: EPJ Web of Conferences: DYMAT 2018 - 12th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading. Paper presented at DYMAT 2018 - 12th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, September 9-14, 2018, Arcachon, France. , 183, Article ID 01040.
Open this publication in new window or tab >>Modelling and characterisation of the high-rate behaviour of rock material
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2018 (English)In: EPJ Web of Conferences: DYMAT 2018 - 12th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, 2018, Vol. 183, article id 01040Conference paper, Published paper (Refereed)
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.

National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-71544 (URN)10.1051/epjconf/201818301040 (DOI)
Conference
DYMAT 2018 - 12th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, September 9-14, 2018, Arcachon, France
Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2019-01-21Bibliographically approved
Marth, S., Häggblad, H.-å. & Oldenburg, M. (2017). A comparison between Stepwise Modelling and Inverse Modelling methods for characterization of press hardened sheet metals. In: Mats Oldenburg, Braham Prakash, Kurt Steinhoff (Ed.), 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2: June 4-7 2017, Atlanta, Georgia, USA : proceedings. Paper presented at 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2, Atlanta, Georgia, 4-7 June 2017 (pp. 281-288). Warrendale, PA: Association for Iron & Steel Technology, AIST
Open this publication in new window or tab >>A comparison between Stepwise Modelling and Inverse Modelling methods for characterization of press hardened sheet metals
2017 (English)In: 6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2: June 4-7 2017, Atlanta, Georgia, USA : proceedings / [ed] Mats Oldenburg, Braham Prakash, Kurt Steinhoff, Warrendale, PA: Association for Iron & Steel Technology, AIST , 2017, p. 281-288Conference paper, Published paper (Refereed)
Abstract [en]

The demand for weight reduction of cars has increased the number of press hardened sheet metal parts used in the automotive industry. This leads to an increased demand on the precision of simulations of press hardened sheet metals. An accurate prediction of the post-necking behaviour of materials is therefore needed to increase the precision of computer simulations with large deformations, as for example in forming simulations and crash simulations. Especially fracture simulations of press hardened steel parts with tailored properties have a huge demand on precise material models.

Inverse modelling is a common engineering tool to characterize the elasto-plastic behaviour of materials.  Taking experimental data, such as force and displacement data, the material model parameters are optimised until the simulated output reaches a target function.  Then inverse modelling is highly time demanding and needs nonlinear hardening material models. 

Lately a new fast method for post necking characterisation of sheet metals, called the Stepwise Modelling Method (SMM), was presented. This method uses full field measurements to obtain the strain field on the surface of sheet metal tensile specimens.  Furthermore, the stepwise modelling method models an experimental hardening curve in a stepwise process.  This hardening curve is a piecewise linear curve and not restricted to any specific material model.

In this paper SMM is used to characterize the hardening behaviour for thermally treated boron steel.  These results are compared with the results of inverse modelling. Three different material models are used. The comparison shows a minor deviation in the resulting hardening relations between stepwise modelling and inverse modelling. Since the efficiency is an important factor in product development calculation times are taken into account.  Comparing calculation time using SMM is considerably more efficient than using inverse modelling. Furthermore another advantage of SMM is shown in the fact that the piecewise linear hardening curves can be fitted to almost any material model without computational costs.

Place, publisher, year, edition, pages
Warrendale, PA: Association for Iron & Steel Technology, AIST, 2017
Series
CHS2-series ; 6
Keywords
Stepwise modelling; Inverse modelling; Material characterisation; Boron steel; Press hardening; Material modelling
National Category
Manufacturing, Surface and Joining Technology Vehicle Engineering Metallurgy and Metallic Materials Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-62459 (URN)978-1-935117-66-7 (ISBN)
Conference
6th International Conference Hot Sheet Metal Forming of High-Performance Steel CHS2, Atlanta, Georgia, 4-7 June 2017
Available from: 2017-03-13 Created: 2017-03-13 Last updated: 2018-04-12Bibliographically approved
Sjöberg, T., Marth, S., Kajberg, J. & Häggblad, H.-å. (2017). Experimental characterisation of the evolution of triaxiality stress state for sheet metal materials. European journal of mechanics. A, Solids, 66, 279-286
Open this publication in new window or tab >>Experimental characterisation of the evolution of triaxiality stress state for sheet metal materials
2017 (English)In: European journal of mechanics. A, Solids, ISSN 0997-7538, E-ISSN 1873-7285, Vol. 66, p. 279-286Article in journal (Refereed) Published
Abstract [en]

Sheet metals are often used as safety structures in automotive applications where the fracture behaviour is a key design parameter. Theoretical and experimental observations have shown that the fracture behaviour of many metals depends on the stress state. Modelling the stress state dependency of fracture in Finite Element (FE) simulations has led to the development of advanced stress state dependent fracture criteria. The calibration of advanced fracture models is currently limited by the characterisation methods, which have not developed much during the last decades. Experimental characterisation methods that can determine the stress state accurately are necessary to ensure reliable calibrations of advanced fracture models. In this article, an experimental method to obtain the stress state and its evolution during deformation is presented. The stress state evolution is determined using measured local displacement field data, which were obtained by digital image correlation, coupled with a stepwise modelling method. This article shows that the stepwise modelling method can capture the stress state evolution for three different specimen geometries subjected to tensile loading. The resulting experimentally determined stress state evolutions are compared with the results of FE simulations, and both results are in good agreement. The accurate stress state evolutions characterised directly from experiments using the proposed method enables calibration of advanced fracture models rapidly and reliably

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-65104 (URN)10.1016/j.euromechsol.2017.07.013 (DOI)000412254300022 ()2-s2.0-85026754631 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-08-15 (andbra)

Available from: 2017-08-15 Created: 2017-08-15 Last updated: 2018-04-12Bibliographically approved
Gustafsson, G., Häggblad, H.-å., Nishida, M., Larsson, S. & Jonsén, P. (2017). Fracture probability modelling of impact-loaded iron ore pellets. International Journal of Impact Engineering, 102, 180-186
Open this publication in new window or tab >>Fracture probability modelling of impact-loaded iron ore pellets
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2017 (English)In: International Journal of Impact Engineering, ISSN 0734-743X, E-ISSN 1879-3509, Vol. 102, p. 180-186Article in journal (Refereed) Published
Abstract [en]

Blast furnace iron ore pellets are sintered, centimetre-sized ore spheres with a high iron content. Together with carbonized coal, iron ore pellets are used in the production of steel. In transporting pellets from pelletizing plants to customers, iron ore pellets are exposed to different static and dynamic loading situations, resulting in strength degradation and, in some cases, fragmentation. This can lead to a reduced gas flow in the blast furnace, which causes reduced quality in steel production. Reliable numerical simulations that can predict the ability of the pellets to endure their handling are important tools for optimizing the design of equipment for iron ore handling. This paper describes the experimental and numerical work performed to investigate the impact fracture behaviour of iron ore pellets at different strain rates. A number of split Hopkinson pressure bar tests with different striker velocities are carried out and analysed to investigate the strain rate dependency of the fracture strength of iron ore pellets. Fracture data for iron ore pellets are derived and expressed in terms of statistical means and standard deviations. A stress based, strain-rate dependent fracture model that takes triaxiality into account is suggested. The fracture model is used and validated with impact tests of iron ore pellets. In the validation experiment, iron ore pellets are fired against a steel plate, and the percentage of fractured pellets at different impact velocities are measured. Finite element simulations of the experiment are carried out and the probability of pellets fracturing during impact are calculated and compared with the experimental results. The agreement between the experiments and numerical simulations shows the validity of the model.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-61326 (URN)10.1016/j.ijimpeng.2016.12.014 (DOI)000393001400017 ()2-s2.0-85008350828 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-01-09 (andbra)

Available from: 2017-01-09 Created: 2017-01-09 Last updated: 2018-09-13Bibliographically approved
Gustafsson, G., Häggblad, H.-å., Larsson, S. & Jonsén, P. (2017). Numerical Prediction of Fracture in Iron Ore Pellets During Handling and Transportation. In: Barry Wills (Ed.), : . Paper presented at Computational Modelling ‘17, Falmouth, Cornwall, UK June 13-14, 2017.
Open this publication in new window or tab >>Numerical Prediction of Fracture in Iron Ore Pellets During Handling and Transportation
2017 (English)In: / [ed] Barry Wills, 2017Conference paper, Published paper (Refereed)
Abstract [en]

Iron ore pellets are sintered, centimetre-sized spheres of ore with high iron content. Together with carbonized coal, iron ore pellets are used in the production of steel. During transportation and handling of iron ore pellets they are exposed to different loads, resulting in degradation of the strength and in some cases fragmentation. The aim of this work is to increase the knowledge of how to design the handling systems for iron ore pellets to decrease the amount of fractured materials in the flows. A numerical finite element model for iron ore pellets fracture probability analysis is presented with a stress based fracture criterion. The model is used to simulate different flows of iron ore pellets hitting guide plates and to predict the proportion of fractured iron ore pellets in the flow. The amount of fractured iron ore pellets are predicted at different flow velocities, showing good agreement with experimental measurements.

Keywords
Modelling, Iron ore pellets, fracture
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-65337 (URN)
Conference
Computational Modelling ‘17, Falmouth, Cornwall, UK June 13-14, 2017
Available from: 2017-08-25 Created: 2017-08-25 Last updated: 2018-04-12Bibliographically approved
Larsson, S., Carbonell, J. M., Rodriguez Prieto, J. M., Gustafsson, G., Jonsén, P., Häggblad, H.-å., . . . Latorre, S. (2017). Numerical simulation and validation of powder filling using particle based methods. In: PARTICLES 2017: . Paper presented at V International Conference on Particle-based Methods, Fundamentals and Applications, Hannover, Germany, 26-28 September 2017.
Open this publication in new window or tab >>Numerical simulation and validation of powder filling using particle based methods
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2017 (English)In: PARTICLES 2017, 2017Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

Powder pressing is a complicated process as the mechanical behaviour of the powder material changes with increasing density. Manufacturers tend to produce components with shapes of increasing complexity requiring improved pressing equipment and methods. Mechanical properties of powder materials changes dramatically from the beginning to the end of the compaction phase. Previous investigations have shown that powder transfer and large powder flow during filling affects the strength of the final component significantly. Combined experimental and numerical studies can improve the understanding of the impact the filling stage has on the final component, e.g. to explain the non-homogeneity of the density of powder pressed parts.This work covers numerical modelling and simulation of powder filling using two different approaches, the discrete element method (DEM) [1,2] which is a micro mechanical based method and the particle finite element method (PFEM) [3] which is a continuum based method. Experimental measurements with digital speckle photography (DSP) [4] from a previous study [5] are used to validate the numerical simulations. The numerical results are compared in terms of agreement with the experimental results, such as velocity- and strain field data. The numerical simulations are further compared in terms of computational efficiency.The comparison of DSP measurements and simulations gives similar flow characteristics. In conclusion, experimental measurements with DSP together with numerical simulation are powerful tools to increase the knowledge of powder filling and also to improve the numerical model prediction. Improved numerical models will facilitate future product development processes and decrease the lead time.

National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-68990 (URN)
Conference
V International Conference on Particle-based Methods, Fundamentals and Applications, Hannover, Germany, 26-28 September 2017
Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2018-06-07Bibliographically approved
Larsson, S., Gustafsson, G., Oudich, A., Jonsén, P. & Häggblad, H.-å. (2016). Experimental methodology for study of granular material flow using digital speckle photography. Chemical Engineering Science, 155, 524-536
Open this publication in new window or tab >>Experimental methodology for study of granular material flow using digital speckle photography
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2016 (English)In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 155, p. 524-536Article in journal (Refereed) Published
Abstract [en]

Granular material flow occurs in many industrial applications, and the characteristics of such flow is challenging to measure. Therefore, an experimental method that captures the flow behavior at different loading situations is desired.

In this work, experimental measurements of granular material flow with digital speckle photography (DSP) are carried out. The granular flow process is recorded with a high-speed camera; the image series are then analyzed using the DSP method. This approach enables field data such as displacement, velocity, and strain fields to be visualized during the granular material flow process. Three different scenarios were studied: free surface flow in a fill shoe, flow without a free surface in a fill shoe, and the rearrangement of material in a cavity. The results showed that it is possible to obtain field data of the motion of particles for all three scenarios with the DSP technique. The presented experimental methodology can be used to capture complex flow behavior of granular material.

National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-59694 (URN)10.1016/j.ces.2016.09.010 (DOI)000385600400045 ()2-s2.0-84987642035 (Scopus ID)
Note

Validerad; 2016; Nivå 2; 2016-10-12 (andbra)

Available from: 2016-10-12 Created: 2016-10-12 Last updated: 2019-03-14Bibliographically approved
Häggblad, H.-å., Jonsén, P., Gustafsson, G., Oldenburg, M. & Golling, S. (2016). Modelling And Simulation The Cracking Of Green Metal Powder Body. In: Proceedings World PM2016 Congress: International Powder Metallurgy Congress & Exhibition 9-13 October 2016, Hamburg, Germany. Paper presented at International Powder Metallurgy Congress & Exhibition, Hamburg, 9-13 October 2016. European Powder Metallurgy Association
Open this publication in new window or tab >>Modelling And Simulation The Cracking Of Green Metal Powder Body
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2016 (English)In: Proceedings World PM2016 Congress: International Powder Metallurgy Congress & Exhibition 9-13 October 2016, Hamburg, Germany, European Powder Metallurgy Association , 2016Conference paper, Published paper (Refereed)
Abstract [en]

During the ejection stage of the powder metallurgy (PM) pressing process the elastic behaviour is important. Especially, if the in the powder compact is unloaded in a non-beneficially manner crack formation can occur. Experiments show a non-linear and also stress dependent elastic behaviour of green bodies. Calibrated against experimental data, a fracture model controlling the stress versus crack-width relationship is used. The softening rate of the fracture model is obtained from the corresponding rate of the dissipated energy. The model is implemented with a smeared crack approach in a finite element code and tested in simulation of a diametral compression testing. Results from simulations correlates well with experimental results. The smeared crack method combined with a cohesive fracture model is an interesting tool for predicting fracture in powder compacts.

Place, publisher, year, edition, pages
European Powder Metallurgy Association, 2016
National Category
Engineering and Technology Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-61125 (URN)978-1-899072-48-4 (ISBN)
Conference
International Powder Metallurgy Congress & Exhibition, Hamburg, 9-13 October 2016
Available from: 2016-12-16 Created: 2016-12-16 Last updated: 2018-04-12Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-7514-0513

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