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Azizoğlu, Yağız
Publications (5 of 5) Show all publications
Azizoğlu, Y., Gärdsback, M., Yamanaka, A., Kuwabara, T. & Lindgren, L.-E. -. (2018). Work hardening during alternating load directions of 316L SS. Paper presented at 17th International Conference on Metal Forming (METAL FORMING 2018) September 16 – 19, 2018, Toyohashi, Japan. Procedia Manufacturing, 15, 1777-1784
Open this publication in new window or tab >>Work hardening during alternating load directions of 316L SS
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2018 (English)In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 15, p. 1777-1784Article in journal (Refereed) Published
Abstract [en]

Understanding and modelling the plastic behavior of a material are essential for simulation and design of metal forming processes. Cold pilgering of tubes is a process with very complex strain history with alternating loading direction. This makes evaluation of the work hardening challenging. Cold deformation applied in a single direction predominantly exhibit work hardening, while changes of the loading direction may even cause softening in other directions. The influence of alternating loading directions on work hardening has been experimentally investigated for 316L stainless steel (SS). Cubic specimens were cut out from the preform of the tube. The specimens are subjected to uniaxial compressions in alternating directions along two perpendicular axes. From the results, a cyclic elastic-plastic constitutive model based on a Chaboche-type approach is calibrated and implemented in the commercial finite element code MSC.Marc.

Keywords
Finite element method (FEM), Isotropic, kinematic hardening, Cyclic plasticity, Chaboche model, Uniaxial / Multiaxial loading, Cold pilgering, Tube forming
National Category
Materials Engineering
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-29915 (URN)10.1016/j.promfg.2018.07.246 (DOI)2-s2.0-85063795502 (Scopus ID)
Conference
17th International Conference on Metal Forming (METAL FORMING 2018) September 16 – 19, 2018, Toyohashi, Japan
Available from: 2019-04-23 Created: 2019-04-23 Last updated: 2019-04-23Bibliographically approved
Azizoğlu, Y., Gärdsback, M., Sjöberg, B. & Lindgren, L.-E. (2017). Finite element analysis of cold pilgering using elastic roll dies. In: : . Paper presented at International Conference on the Technology of Plasticity, ICTP 2017, Cambridge, United Kingdom, 17-22 September 2017. Elsevier
Open this publication in new window or tab >>Finite element analysis of cold pilgering using elastic roll dies
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

A finite element model of cold pilgering with elastic roll dies have been developed and used to investigate the influence of roll die deformation on the material flow, contact region, roll separating force and tube dimensions. Full scale experiments were performed to validate the contact surface and tube dimensions. The results show that the influence of roll die flattening is not significant on the contact length. However, elastic deformation of roll die has strong influence on both the wall thickness reduction and roll separating force. Thus it is recommended to consider elasticity of roll dies when forces and tube dimensions are estimated.

Place, publisher, year, edition, pages
Elsevier, 2017
Series
Procedia Engineering, ISSN 1877-7058 ; 2017
Keywords
cold pilgering; cold forming; tube forming; roll flattening; contact length; roll separating force; finite element method; tool elasticity; tube dimension
National Category
Applied Mechanics
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-25901 (URN)10.1016/j.proeng.2017.10.1010 (DOI)
Conference
International Conference on the Technology of Plasticity, ICTP 2017, Cambridge, United Kingdom, 17-22 September 2017
Available from: 2017-08-29 Created: 2017-08-29 Last updated: 2017-12-18Bibliographically approved
Azizoğlu, Y. (2017). Modeling of Cold Pilgering of Tubes. (Licentiate dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Modeling of Cold Pilgering of Tubes
2017 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Cold pilgering is a challenging tube forming process in terms of modeling due to the complexity in kinematic of tools, friction condition and material behavior. The process development has mostly been based on simple formulas and costly full-scale tryouts. The aim in this study is to develop validated Finite element models of cold pilgering to increase the understanding of influence of the process parameters on the produced tubes.

In the course of this thesis, three-dimensional mechanical and thermo-mechanical Finite element models of cold pilgering were developed. The commercial code MSC.Marc was used in the simulations. General 3D models are needed to be able to capture asymmetric deformation in cold pilgering. It was found that tool deflections together with elastic deformation of roll dies have considerable influence on the rolling force. Furthermore, the strain rate and temperature effects on the response of the material and thereby on the rolling force were evaluated.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2017
Series
Licentiate thesis, ISSN 1402-1757
Keywords
Cold pilgering, finite element method, tube forming, tool elasticity, roll flattening
National Category
Applied Mechanics
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-25902 (URN)978-91-7583-873-1 (ISBN)978-91-7583-872-4 (ISBN)
Presentation
2017-05-31, E130, Luleå tekniska universitet, Luleå, 10:25 (English)
Opponent
Supervisors
Available from: 2017-08-29 Created: 2017-08-29 Last updated: 2017-08-29Bibliographically approved
Azizoğlu, Y., Gärdsback, M., Sjöberg, B. & Lindgren, L.-E. (2016). Finite element modeling of tube deformation during cold pilgering. In: MATEC Web of Conferences: . Paper presented at NUMIFORM 2016: The 12th International Conference on Numerical Methods in Industrial Forming Processes. , 80, Article ID 15004.
Open this publication in new window or tab >>Finite element modeling of tube deformation during cold pilgering
2016 (English)In: MATEC Web of Conferences, 2016, Vol. 80, article id 15004Conference paper, Published paper (Refereed)
Abstract [en]

A three-dimensional finite element model of cold pilgering of stainless steel tubes is developed in this paper. The objective is to use the model to increase the understanding of forces and deformations in the process. The focus is on the influence of vertical displacements of the roll stand and axial displacements of the mandrel and tube. Therefore, the rigid tools and the tube are supported with elastic springs. Additionally, the influences of friction coefficients in the tube/mandrel and tube/roll interfaces are examined. A sensitivity study is performed to investigate the influences of these parameters on the strain path and the roll separation force. The results show the importance of accounting for the displacements of the tube and rigid tools on the roll separation force and the accumulative plastic strain.

Series
MATEC Web of Conferences, E-ISSN 2261-236X
Keywords
cold forming
National Category
Materials Engineering
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-23429 (URN)10.1051/matecconf/20168015004 (DOI)000392331100086 ()
Conference
NUMIFORM 2016: The 12th International Conference on Numerical Methods in Industrial Forming Processes
Available from: 2016-11-21 Created: 2016-11-21 Last updated: 2017-08-29Bibliographically approved
Azizoğlu, Y., Gardsback, M., Sjoberg, B. & Lindgren, L.-E. -. (2015). Finite element modelling of cold pilgering of tubes. In: Proceedings of the 8th International Conference on Computational Plasticity - Fundamentals and Applications, COMPLAS 2015: . Paper presented at 13th International Conference on Computational Plasticity, COMPLAS 2015, 1 September 2015 through 3 September 2015 (pp. 716-726).
Open this publication in new window or tab >>Finite element modelling of cold pilgering of tubes
2015 (English)In: Proceedings of the 8th International Conference on Computational Plasticity - Fundamentals and Applications, COMPLAS 2015, 2015, p. 716-726Conference paper, Published paper (Refereed)
Abstract [en]

Cold pilgering is a cold forming process used during manufacturing of seamless tubes. The tube with a mandrel inside is fed forward and rotated in stepwise increments, while the roll stand moves back and forth. The total plastic deformation of the tube is such that the cross-sectional area of the tube decreases and the length of the tube increases during the process. However, this is performed in many small incremental steps, where the direction of deformation in a material point changes at each stroke. Most published models of cold pilgering use simplified material models. In reality, the flow stress is dependent on temperature, strain rate, strain history and microstructure. In this work, temperature and strain rate distributions are computed, using a 3D thermo-mechanical FE model, and the influence of temperature and strain rate on the rolling force is investigated. The Johnson-Cook model is employed to describe the flow stress using isotropic hardening. The results show that strain rate and temperature have a significant influence on the roll separation force.

Keywords
Cold forming, Cold pilgering, Finite element analysis, Johnson-cook, Seamless tubes, Thermo-mechanical analysis, Von mises plasticity, Finite element method, Plastic flow, Plasticity, Tubes (components), Tubing, Pilgering, Von-Mises plasticity, Strain rate
National Category
Materials Engineering
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-21303 (URN)000380573600069 ()2-s2.0-84992261190 (Scopus ID)9788494424465 (ISBN)
Conference
13th International Conference on Computational Plasticity, COMPLAS 2015, 1 September 2015 through 3 September 2015
Available from: 2016-03-31 Created: 2016-03-31 Last updated: 2017-08-29Bibliographically approved
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