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Wikman, Bengt
Publikasjoner (10 av 24) Visa alla publikasjoner
Zakrisson, B., Häggblad, H.-Å. & Wikman, B. (2011). Numerical simulations of blast loads and structural deformation from near-field explosions in air (ed.). Paper presented at . International Journal of Impact Engineering, 38(7), 597-612
Åpne denne publikasjonen i ny fane eller vindu >>Numerical simulations of blast loads and structural deformation from near-field explosions in air
2011 (engelsk)Inngår i: International Journal of Impact Engineering, ISSN 0734-743X, E-ISSN 1879-3509, Vol. 38, nr 7, s. 597-612Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Numerical simulations of air blast loading in the near-field acting on deformable steel plates have been performed and compared to experiments. Two types of air blast setups have been used, cylindrical explosive placed either in free air or in a steel pot. A numerical finite element convergence study of the discretisation sensitivity for the gas dynamics has been performed, with use of mapping results from 2D to 3D in an Eulerian reference frame. The result from the convergence study served as a foundation for development of the simulation models. Considering both air blast setups, the numerical results under predicted the measured plate deformations with 9.4–11.1%. Regarding the impulse transfer, the corresponding under prediction was only 1.0–1.6%. An influence of the friction can be shown, both in experiments and the simulations, although other uncertainties are involved as well. A simplified blast model based on empirical blast loading data representing spherical and hemispherical explosive shapes has been tested as an alternative to the Eulerian model. The result for the simplified blast model deviates largely compared to the experiments and the Eulerian model. The CPU time for the simplified blast model is however considerably shorter, and may still be useful in time consuming concept studies. All together, reasonable numerical results using reasonable model sizes can be achieved from near-field explosions in air.

Emneord
Engineering mechanics - Fluid mechanics, Teknisk mekanik - Strömningsmekanik
HSV kategori
Forskningsprogram
Hållfasthetslära
Identifikatorer
urn:nbn:se:ltu:diva-3428 (URN)10.1016/j.ijimpeng.2011.02.005 (DOI)000291508300008 ()140b8670-6977-4461-8afe-044db59d945b (Lokal ID)140b8670-6977-4461-8afe-044db59d945b (Arkivnummer)140b8670-6977-4461-8afe-044db59d945b (OAI)
Merknad
Validerad; 2011; 20110324 (bjozak)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Kajberg, J. & Wikman, B. (2007). Viscoplastic parameter estimation by high strain-rate experiments and inverse modelling: speckle measurements and high-speed photography (ed.). International Journal of Solids and Structures, 44(1), 145-164
Åpne denne publikasjonen i ny fane eller vindu >>Viscoplastic parameter estimation by high strain-rate experiments and inverse modelling: speckle measurements and high-speed photography
2007 (engelsk)Inngår i: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 44, nr 1, s. 145-164Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

A methodology based on inverse modelling for estimating viscoplastic material parameters at high strain-rate conditions is presented. The methodology is demonstrated for a mild steel exposed for compression loading in a split Hopkinson pressure bar arrangement. By using dog-bone shaped specimens nonhomogeneous states of deformation are obtained throughout the entire deformation process. The resulting nonhomogeneous deformation of the specimens is evaluated using digital speckle photography (DSP) to give in-plane point-wise displacement and strain fields. The photographs are captured with a high-speed camera of image converter type, which acquire time resolved images during the impact loading. The experiments are simulated using finite element analysis (FEA), where the material model suggested by Johnson-Cook for high-strain rate conditions are utilised. Experimental and FE-calculated field information are compared in order to estimate the viscoplastic parameter in the Johnson-Cook material model. The estimation is performed by minimising least-square functions that contain the differences in displacements and strains, respectively. The quality of the estimated parameters is studied from statistical point of view.

HSV kategori
Forskningsprogram
Hållfasthetslära
Identifikatorer
urn:nbn:se:ltu:diva-11673 (URN)10.1016/j.ijsolstr.2006.04.018 (DOI)000242925800009 ()2-s2.0-33750732302 (Scopus ID)ab106070-6828-11dc-a0c3-000ea68e967b (Lokal ID)ab106070-6828-11dc-a0c3-000ea68e967b (Arkivnummer)ab106070-6828-11dc-a0c3-000ea68e967b (OAI)
Merknad

Validerad; 2007; 20070921 (pirkko)

Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Wikman, B., Bergman, G., Oldenburg, M. & Häggblad, H.-å. (2006). Estimation of constitutive parameters for powder pressing by inverse modelling (ed.). Paper presented at . Structural and multidisciplinary optimization (Print), 31(5), 400-409
Åpne denne publikasjonen i ny fane eller vindu >>Estimation of constitutive parameters for powder pressing by inverse modelling
2006 (engelsk)Inngår i: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 31, nr 5, s. 400-409Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Powder metallurgy processes are used in many material technologies for manufacturing of a wide range of industrial parts. Products such as components for cars, cemented carbides and high-speed steels for mechanical cutting, magnets and soft magnetic materials, bearings and refractory metals are made from powder. These parts are manufactured by powder die pressing followed by sintering of the resulting green body in a furnace. Traditionally, experience-based methods have been used to design and adapt the processing variables for optimal performance. Cost savings can be made if the tool design can be based on reliable predictive numerical simulations of the powder compaction process. Computer modelling could aid process and design engineers in selecting and optimizing the best pressing route for many industrial components. The aim of the present work has been to develop an efficient way to determine the necessary constitutive model parameters of the numerical models by means of inverse modelling. An experiment for establishing input data to the inverse problem has been designed and validated. The objective function is formed based on the discrepancy in force-displacement data between the numerical model prediction and the experiment. Minimization of the objective function with respect to the material parameters is performed using an in-house optimization software shell which is built on a modified Nelder-Mead simplex method also known as the subplex method. The completed analyses show that the proposed approach can readily be used to determine material parameters.

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Forskningsprogram
Hållfasthetslära
Identifikatorer
urn:nbn:se:ltu:diva-7121 (URN)10.1007/s00158-005-0556-7 (DOI)000242612000008 ()2-s2.0-33751299782 (Scopus ID)5707ece0-a59c-11db-9811-000ea68e967b (Lokal ID)5707ece0-a59c-11db-9811-000ea68e967b (Arkivnummer)5707ece0-a59c-11db-9811-000ea68e967b (OAI)
Merknad
Validerad; 2006; 20070111 (inah)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Oldenburg, M., Sundin, K.-G., Wikman, B., Kajberg, J. & Åkerström, P. (2006). Material characterisation using advanced experiments and inverse methods (ed.). In: (Ed.), Zhenhan Yao; Mingwu Yuan; Wanxie Zhong (Ed.), Computational mechanics: Abstracts : abstracts of the papers presented at the regular sessions of the sixth world congress on computational mechanics in conjunction with the second Asian-Pacific congress on computational mechanics, September 5-10, 2004, Beijing, China. Paper presented at World Congress on Computational Mechanics : 05/09/2004 - 10/09/2004. Bejing: Tsinghua University Press
Åpne denne publikasjonen i ny fane eller vindu >>Material characterisation using advanced experiments and inverse methods
Vise andre…
2006 (engelsk)Inngår i: Computational mechanics: Abstracts : abstracts of the papers presented at the regular sessions of the sixth world congress on computational mechanics in conjunction with the second Asian-Pacific congress on computational mechanics, September 5-10, 2004, Beijing, China / [ed] Zhenhan Yao; Mingwu Yuan; Wanxie Zhong, Bejing: Tsinghua University Press, 2006Konferansepaper, Meeting abstract (Annet vitenskapelig)
sted, utgiver, år, opplag, sider
Bejing: Tsinghua University Press, 2006
HSV kategori
Forskningsprogram
Hållfasthetslära
Identifikatorer
urn:nbn:se:ltu:diva-28329 (URN)2198fc20-fa0b-11db-b2dd-000ea68e967b (Lokal ID)7-302-09343-1 (ISBN)2198fc20-fa0b-11db-b2dd-000ea68e967b (Arkivnummer)2198fc20-fa0b-11db-b2dd-000ea68e967b (OAI)
Konferanse
World Congress on Computational Mechanics : 05/09/2004 - 10/09/2004
Merknad
Godkänd; 2006; 20070504 (cira)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2017-11-25bibliografisk kontrollert
Åkerström, P., Wikman, B. & Oldenburg, M. (2005). Material parameter estimation for boron steel from simultaneous cooling and compression experiments (ed.). Paper presented at . Modelling and Simulation in Materials Science and Engineering, 13(8), 1291-1308
Åpne denne publikasjonen i ny fane eller vindu >>Material parameter estimation for boron steel from simultaneous cooling and compression experiments
2005 (engelsk)Inngår i: Modelling and Simulation in Materials Science and Engineering, ISSN 0965-0393, E-ISSN 1361-651X, Vol. 13, nr 8, s. 1291-1308Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

In order to increase the accuracy of numerical simulations of the hot stamping process, reliable material data is crucial. Traditionally, the material is characterized by several isothermal compression or tension tests performed at elevated temperatures and different strain rates. The drawback of the traditional methods is the appearance of unwanted phases for some test temperatures and durations. Such an approach is also both time consuming and expensive. In the present work an alternative approach is proposed, which reduces unwanted phase changes and the number of experiments. The isothermal mechanical response is established through inverse modelling of simultaneous cooling and compression experiments. The estimated material parameters are validated by comparison with data from a separate forming experiment. The computed global response is shown to be in good agreement with the experiments.

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Forskningsprogram
Hållfasthetslära
Identifikatorer
urn:nbn:se:ltu:diva-4410 (URN)10.1088/0965-0393/13/8/007 (DOI)000234460700007 ()2-s2.0-28844444655 (Scopus ID)25c0db70-89df-11db-8975-000ea68e967b (Lokal ID)25c0db70-89df-11db-8975-000ea68e967b (Arkivnummer)25c0db70-89df-11db-8975-000ea68e967b (OAI)
Merknad
Validerad; 2005; 20061212 (ysko)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Westman, E.-L., Pederson, R., Wikman, B. & Oldenburg, M. (2004). Numerical and microstructural evaluation of elevated temperature compression tests on Ti-6AI-4V (ed.). In: (Ed.), Gerd Lütjering (Ed.), Ti-2003 : science and technology: proceedings of the 10. World Conference on Titanium, held at the CCH-Congress Center Hamburg, Germany, 13 - 18 July 2003. Paper presented at World Conference on Titanium : 13/07/2003 - 18/07/2003. Weinheim: John Wiley & Sons
Åpne denne publikasjonen i ny fane eller vindu >>Numerical and microstructural evaluation of elevated temperature compression tests on Ti-6AI-4V
2004 (engelsk)Inngår i: Ti-2003 : science and technology: proceedings of the 10. World Conference on Titanium, held at the CCH-Congress Center Hamburg, Germany, 13 - 18 July 2003 / [ed] Gerd Lütjering, Weinheim: John Wiley & Sons, 2004Konferansepaper, Publicerat paper (Fagfellevurdert)
sted, utgiver, år, opplag, sider
Weinheim: John Wiley & Sons, 2004
HSV kategori
Forskningsprogram
Hållfasthetslära
Identifikatorer
urn:nbn:se:ltu:diva-29542 (URN)30c9f5e0-fa3e-11db-b2dd-000ea68e967b (Lokal ID)3-527-30306-5 (ISBN)30c9f5e0-fa3e-11db-b2dd-000ea68e967b (Arkivnummer)30c9f5e0-fa3e-11db-b2dd-000ea68e967b (OAI)
Konferanse
World Conference on Titanium : 13/07/2003 - 18/07/2003
Merknad
Godkänd; 2004; 20070504 (cira)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2017-11-25bibliografisk kontrollert
Wikman, B. & Häggblad, H.-å. (2003). Design of the container for hot isostatic pressing of a diesel engine piston top (ed.). Paper presented at . P / M Science & Technology Briefs, 5(1), 10-14
Åpne denne publikasjonen i ny fane eller vindu >>Design of the container for hot isostatic pressing of a diesel engine piston top
2003 (engelsk)Inngår i: P / M Science & Technology Briefs, ISSN 1527-2478, Vol. 5, nr 1, s. 10-14Artikkel i tidsskrift (Annet vitenskapelig) Published
Abstract [en]

Numerical simulations of the hot isostatic pressing (HIP) process for manufacturing of a piston top have been used to achieve near net shape in this work. The shape of the container is optimised by repeated simulations of the manufacturing process. The application is a piston top for a large diesel engine. The aim is to contribute to the development of an integrated computer based tool for the design and manufacture of hot isostatically pressed products. The computer aided concurrent engineering (CACE) system which is integrated using a relational database includes the solid modeller of a computer aided design system, codes for non-linear finite element analysis (FEA), and data from a coordinate measuring system (CMM). Predictions of near net shape geometry obtained numerically are in tolerable agreement with experimental measurements. The model is based on an associated flow rule and linear isotropic hardening is assumed, the material properties correspond to AISI 304 steel.

Abstract [en]

Numerical simulations of the hot isostatic pressing (HIP) process for manufacturing of a piston top have been used to achieve near net shape in this work. The shape of the container is optimised by repeated simulations of the manufacturing process. The application is a piston top for a large diesel engine. The aim is to contribute to the development of an integrated computer based tool for the design and manufacture of hot isostatically pressed products. The computer aided concurrent engineering (CACE) system which is integrated using a relational database includes the solid modeller of a computer aided design system, codes for non-linear finite element analysis (FEA), and data from a coordinate measuring system (CMM). Predictions of near net shape geometry obtained numerically are in tolerable agreement with experimental measurements. The model is based on an associated flow rule and linear isotropic hardening is assumed, the material properties correspond to AISI 304 steel. Udgivelsesdato: March

HSV kategori
Forskningsprogram
Hållfasthetslära
Identifikatorer
urn:nbn:se:ltu:diva-5720 (URN)3e4f46f0-8d4e-11db-8975-000ea68e967b (Lokal ID)3e4f46f0-8d4e-11db-8975-000ea68e967b (Arkivnummer)3e4f46f0-8d4e-11db-8975-000ea68e967b (OAI)
Merknad
Godkänd; 2003; 20061216 (ysko)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-04-12bibliografisk kontrollert
Oldenburg, M., Häggblad, H.-å. & Wikman, B. (2002). Material model parameter estimation by inverse analysis of a closed die experiment (ed.). In: (Ed.), Alan Lawley (Ed.), Process modeling in powder metallurgy & particulate materials: proceedings of the 2002 International Conference on Process Modeling in Powder Metallurgy & Particulate Materials, [held October 28 - 29, 2002, Newport Beach, California]. Paper presented at International Conference on Process Modeling in Powder Metallurgy & Particulate Materials : 28/10/2002 - 29/10/2002. Prinecton; NJ: Metal powder industries federation
Åpne denne publikasjonen i ny fane eller vindu >>Material model parameter estimation by inverse analysis of a closed die experiment
2002 (engelsk)Inngår i: Process modeling in powder metallurgy & particulate materials: proceedings of the 2002 International Conference on Process Modeling in Powder Metallurgy & Particulate Materials, [held October 28 - 29, 2002, Newport Beach, California] / [ed] Alan Lawley, Prinecton; NJ: Metal powder industries federation , 2002Konferansepaper, Publicerat paper (Fagfellevurdert)
sted, utgiver, år, opplag, sider
Prinecton; NJ: Metal powder industries federation, 2002
HSV kategori
Forskningsprogram
Hållfasthetslära
Identifikatorer
urn:nbn:se:ltu:diva-27898 (URN)17adeb60-f977-11db-b2dd-000ea68e967b (Lokal ID)1-87895-492-X (ISBN)17adeb60-f977-11db-b2dd-000ea68e967b (Arkivnummer)17adeb60-f977-11db-b2dd-000ea68e967b (OAI)
Konferanse
International Conference on Process Modeling in Powder Metallurgy & Particulate Materials : 28/10/2002 - 29/10/2002
Merknad
Godkänd; 2002; 20070503 (cira)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2018-04-12bibliografisk kontrollert
Wikman, B., Reyre, M. & Häggblad, H.-å. (2002). Three dimentional finite element analysis of powder compaction (ed.). In: (Ed.), Alan Lawley (Ed.), Process modeling in powder metallurgy & particulate materials: proceedings of the 2002 International Conference on Process Modeling in Powder Metallurgy & Particulate Materials, [held October 28 - 29, 2002, Newport Beach, California]. Paper presented at International Conference on Process Modeling in Powder Metallurgy & Particulate Materials : 28/10/2002 - 29/10/2002 (pp. 115-122). Princeton, NJ: Metal powder industries federation
Åpne denne publikasjonen i ny fane eller vindu >>Three dimentional finite element analysis of powder compaction
2002 (engelsk)Inngår i: Process modeling in powder metallurgy & particulate materials: proceedings of the 2002 International Conference on Process Modeling in Powder Metallurgy & Particulate Materials, [held October 28 - 29, 2002, Newport Beach, California] / [ed] Alan Lawley, Princeton, NJ: Metal powder industries federation , 2002, s. 115-122Konferansepaper, Publicerat paper (Fagfellevurdert)
sted, utgiver, år, opplag, sider
Princeton, NJ: Metal powder industries federation, 2002
HSV kategori
Forskningsprogram
Hållfasthetslära
Identifikatorer
urn:nbn:se:ltu:diva-37090 (URN)afa95950-f976-11db-b2dd-000ea68e967b (Lokal ID)1-87895-492-X (ISBN)afa95950-f976-11db-b2dd-000ea68e967b (Arkivnummer)afa95950-f976-11db-b2dd-000ea68e967b (OAI)
Konferanse
International Conference on Process Modeling in Powder Metallurgy & Particulate Materials : 28/10/2002 - 29/10/2002
Merknad
Godkänd; 2002; 20070503 (cira)Tilgjengelig fra: 2016-10-03 Laget: 2016-10-03 Sist oppdatert: 2018-04-12bibliografisk kontrollert
Wikman, B., Svoboda, A. & Häggblad, H.-å. (2000). A combined material model for numerical simulation of hot isostatic pressing (ed.). Paper presented at . Computer Methods in Applied Mechanics and Engineering, 189(3), 901-913
Åpne denne publikasjonen i ny fane eller vindu >>A combined material model for numerical simulation of hot isostatic pressing
2000 (engelsk)Inngår i: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 189, nr 3, s. 901-913Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

In modelling of hot isostatic pressing (HIP) of powder materials the constitutive model should be able to describe different deformation mechanisms during the consolidation process. In the early stage, the consolidation is dominated by granular behaviour. As temperature and pressure increase in the powder the deformation can be described by a viscoplastic model. Experimental observations show substantial time-independent deformation in the early stage. At this stage of the densification process, pores in the powder are still interconnected. This cannot be described properly by a viscoplastic model. The inconsistency between the deformation mechanisms can be treated by a combined elasto-plastic and elasto-viscoplastic model. Here a granular plasticity model is combined with a viscoplastic model. In previous works the viscoplastic model, power-law breakdown, has been used to describe the entire deformation process. The combined model is implemented into an in-house finite deformation code for the solution of coupled thermomechanical problems. The simulation of a hot isostatic pressing test with dilatometer is performed in order to compare calculated results with the experimental measurement. The results from previously performed analysis carried out with a viscoplastic model only are also compared. Analysis with the combined material model shows good agreement with the experiment for the whole densification process.

HSV kategori
Forskningsprogram
Materialmekanik; Hållfasthetslära
Identifikatorer
urn:nbn:se:ltu:diva-15294 (URN)10.1016/S0045-7825(99)00406-5 (DOI)000089387700010 ()2-s2.0-0034282373 (Scopus ID)ec987cf0-4f86-11db-9592-000ea68e967b (Lokal ID)ec987cf0-4f86-11db-9592-000ea68e967b (Arkivnummer)ec987cf0-4f86-11db-9592-000ea68e967b (OAI)
Merknad
Validerad; 2000; 20060915 (cira)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert