1. Numerical analysis of constraint effect on ductile tearing in strength mismatched welded CCT specimens using micromechanical approachBashir Younise, Marko Rakin, Bojan Medjo, Nenad Gubeljak, Dražan Kozak, Aleksandar Sedmak, 2011, izvirni znanstveni članek Opis: In this paper, constraint effect on ductile fracture initiation and propagation has been studied. Three-dimensional finite element analyses of mismatched welded joints made of high strength steel, have been performed for centre-cracked tensile (CCT) specimens. Different weld widths and material mismatching ratios have been considered. Ductile fracture parameter, crack tip opening displacement at crack growth initiation (CTODi), has been obtained for centre-cracked tensile (CCT) specimens using local approach to fracture and compared with experimental results of single edge bend specimens. Micromechanical complete Gurson model has been applied to investigate fracture behaviour of cracked welded joints. Crack tip constraint has been analysed through stress triaxiality in order to study transferability of fracture parameters from one geometry to another.
Ključne besede: constraint effect, ductile fracture, finite element analysis, material mismatching, stress triaxiality, transferability
Objavljeno: 01.06.2012; Ogledov: 929; Prenosov: 57
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2. Micromechanical analysis of constraint effect on fracture initiation in strength mis-matched welded jointsMiloš Dobrojević, Marko Rakin, Nenad Gubeljak, I. Cvijović, Milorad Zrilić, N. Krunich, Aleksandar Sedmak, 2007, izvirni znanstveni članek Opis: In this paper the micromechanical approach to ductile fracture was applied in a study of constraint effect crack growth initiation in mismatched welded joints. The single edged- notched bend specimens (precrack length ▫$a_o/W=0.32$▫) were experimentally and numerically analysed. The coupled micromechanical model prposed by Gurson, Tvergaard and Needleman was used. Constraint effect was tested by varying widths of the welded joints (6, 12 and 18 mm). HSLA steel was used as the base metal in a quenched and tempered condition. The flux-cored arx-welding process in shielding gas was used. Two different fillers were selected to obtain over- and undermatched weld metal. The micromechanical parameters used in prediction of the crack growth initiation on precracked specimen were calibrated on a round smmoth specimen. The difference in fracture behaviour between over- and undermatched welded joints obtained in experimental results was followed by numerical computationsof void volume fraction in front of the crack tip.
Ključne besede: fracture mechanics, ductile fracture, high strength low alloyed steel, cracks, micromechanical model, mismatched welded joints, constraint effect, void growth
Objavljeno: 01.06.2012; Ogledov: 1079; Prenosov: 51
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3. Distortion of the substructure of a 20-ft shipping container exposed to zinc hot-dip galvanizingIvana Ivanović, Aleksandar Sedmak, Rebeka Rudolf, Leo Gusel, Biljana Grujić, 2013, izvirni znanstveni članek Opis: The main goal of this study was to build a model for a numerical simulation of hot-dip galvanizing of a 20-ft ISO shipping container. For that purpose, the basic transient thermo-mechanical problem of a steel structure under the influence of the temperature characteristic for a zinc hot-dip galvanizing bath was analyzed. Numerical calculations were performed for a simple part and for the complex substructure of the container. Calculations were carried out on the Salome-Meca platform using a Netgen mesh generator and a Code_Asterfinite-element solver.
Ključne besede: shipping container, structural steel, zinc hot-dip galvanizing, transient heat transfer, distortion
Objavljeno: 10.07.2015; Ogledov: 397; Prenosov: 37
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4. Superplastic deformation of an X7093 Al alloySrdjan Tadić, Aleksandar Sedmak, Radica Prokić-Cvetković, Abdsalam Eramah, Rebeka Rudolf, 2014, izvirni znanstveni članek Opis: We have investigated the superplastic deformation mechanism of a powder-metallurgy, high-zinc X7093 Al alloy. The objective was to examine the rate-controlling mechanisms that govern its superplastic deformation. The investigations were carried out in the temperature range 490–524 °C and strain rates of 4.17 × 10–5 s–1 to 2.1 × 10–2 s–1. The maximum ductility was slightly more than 500 % at 524 °C and 4.2 × 10–4 s–1. The values of the stress exponent (n) and the activation energy (Q) indicated that the deformation is rate-controlled by the climb within the grain-boundary diffusion path. The existence of a temperature-dependent threshold stress was confirmed.
Ključne besede: superplasticity, Al alloys, deformation mechanisms
Objavljeno: 23.03.2017; Ogledov: 315; Prenosov: 35
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5. Numerical analysis of temperature field during hardfacing process and comparison with experimental resultsVukić Lazić, Ivana Ivanović, Aleksandar Sedmak, Rebeka Rudolf, Mirjana Lazić, Zoran Radaković, 2014, izvirni znanstveni članek Opis: The three-dimensional transient nonlinear thermal analysis of the hard facing process is performed by using the finite element method. The simulations were executed on the open source Salome platform using the open source finite element solver Code Aster. The Gaussian double ellipsoid was selected in order to enable greater possibilities for the calculation of the moving heat source. The numerical results were compared with available experimental results.
Ključne besede: welding simulations, numerical analysis, thermal analysis, simulations, transient heat conduction, moving heat source
Objavljeno: 07.07.2017; Ogledov: 258; Prenosov: 189
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