Numerical and Experimental Investigations of Fracture Behaviour of Welded Joints with Multiple Defects
Current standards related to welded joint defects (EN ISO 5817) only consider individual cases (i.e., single defect in a welded joint). The question remains about the behaviour of a welded joint in the simultaneous presence of several different types of defects, so-called multiple defects, which is...
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doaj-443598d6bb2a45c68e6ad6ee2220b1602021-09-09T13:50:44ZengMDPI AGMaterials1996-19442021-08-01144832483210.3390/ma14174832Numerical and Experimental Investigations of Fracture Behaviour of Welded Joints with Multiple DefectsMihajlo Aranđelović0Simon Sedmak1Radomir Jovičić2Srđa Perković3Zijah Burzić4Dorin Radu5Zoran Radaković6Innovation Centre of the Faculty of Mechanical Engineering, 11120 Belgrade, SerbiaInnovation Centre of the Faculty of Mechanical Engineering, 11120 Belgrade, SerbiaInnovation Centre of the Faculty of Mechanical Engineering, 11120 Belgrade, SerbiaMilitary Technical Institute, 11030 Belgrade, SerbiaMilitary Technical Institute, 11030 Belgrade, SerbiaFaculty of Civil Engineering, University of Transylvania, 500036 Brașov, RomaniaFaculty of Mechanical Engineering, University of Belgrade, 11120 Belgrade, SerbiaCurrent standards related to welded joint defects (EN ISO 5817) only consider individual cases (i.e., single defect in a welded joint). The question remains about the behaviour of a welded joint in the simultaneous presence of several different types of defects, so-called multiple defects, which is the topic of this research. The main focus is on defects most commonly encountered in practice, such as linear misalignments, undercuts, incomplete root penetration, and excess weld metal. The welding procedure used in this case was metal active gas welding, a common technique when it comes to welding low-alloy low-carbon steels, including those used for pressure equipment. Different combinations of these defects were deliberately made in welded plates and tested in a standard way on a tensile machine, along with numerical simulations using the finite element method (FEM), based on real geometries. The goal was to predict the behaviour in terms of stress concentrations caused by geometry and affected by multiple defects and material heterogeneity. Numerical and experimental results were in good agreement, but only after some modifications of numerical models. The obtained stress values in the models ranged from noticeably lower than the yield stress of the used materials to slightly higher than it, suggesting that some defect combinations resulted in plastic strain, whereas other models remained in the elastic area. The stress–strain diagram obtained for the first group (misalignment, undercut, and excess root penetration) shows significantly less plasticity. Its yield stress is very close to its ultimate tensile strength, which in turn is noticeably lower compared with the other three groups. This suggests that welded joints with misalignment and incomplete root penetration are indeed the weakest of the four groups either due to the combination of the present defects or perhaps because of an additional unseen internal defect. From the other three diagrams, it can be concluded that the test specimens show very similar behaviour with nearly identical ultimate tensile strengths and considerable plasticity. The diagrams shows the most prominent yielding, with an easily distinguishable difference between the elastic and plastic regions. The diagrams are the most similar, having the same strain of around 9% and with a less obvious yield stress limit.https://www.mdpi.com/1996-1944/14/17/4832welded jointfinite element method (FEM)multiple defectsstress concentration |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Mihajlo Aranđelović Simon Sedmak Radomir Jovičić Srđa Perković Zijah Burzić Dorin Radu Zoran Radaković |
spellingShingle |
Mihajlo Aranđelović Simon Sedmak Radomir Jovičić Srđa Perković Zijah Burzić Dorin Radu Zoran Radaković Numerical and Experimental Investigations of Fracture Behaviour of Welded Joints with Multiple Defects Materials welded joint finite element method (FEM) multiple defects stress concentration |
author_facet |
Mihajlo Aranđelović Simon Sedmak Radomir Jovičić Srđa Perković Zijah Burzić Dorin Radu Zoran Radaković |
author_sort |
Mihajlo Aranđelović |
title |
Numerical and Experimental Investigations of Fracture Behaviour of Welded Joints with Multiple Defects |
title_short |
Numerical and Experimental Investigations of Fracture Behaviour of Welded Joints with Multiple Defects |
title_full |
Numerical and Experimental Investigations of Fracture Behaviour of Welded Joints with Multiple Defects |
title_fullStr |
Numerical and Experimental Investigations of Fracture Behaviour of Welded Joints with Multiple Defects |
title_full_unstemmed |
Numerical and Experimental Investigations of Fracture Behaviour of Welded Joints with Multiple Defects |
title_sort |
numerical and experimental investigations of fracture behaviour of welded joints with multiple defects |
publisher |
MDPI AG |
series |
Materials |
issn |
1996-1944 |
publishDate |
2021-08-01 |
description |
Current standards related to welded joint defects (EN ISO 5817) only consider individual cases (i.e., single defect in a welded joint). The question remains about the behaviour of a welded joint in the simultaneous presence of several different types of defects, so-called multiple defects, which is the topic of this research. The main focus is on defects most commonly encountered in practice, such as linear misalignments, undercuts, incomplete root penetration, and excess weld metal. The welding procedure used in this case was metal active gas welding, a common technique when it comes to welding low-alloy low-carbon steels, including those used for pressure equipment. Different combinations of these defects were deliberately made in welded plates and tested in a standard way on a tensile machine, along with numerical simulations using the finite element method (FEM), based on real geometries. The goal was to predict the behaviour in terms of stress concentrations caused by geometry and affected by multiple defects and material heterogeneity. Numerical and experimental results were in good agreement, but only after some modifications of numerical models. The obtained stress values in the models ranged from noticeably lower than the yield stress of the used materials to slightly higher than it, suggesting that some defect combinations resulted in plastic strain, whereas other models remained in the elastic area. The stress–strain diagram obtained for the first group (misalignment, undercut, and excess root penetration) shows significantly less plasticity. Its yield stress is very close to its ultimate tensile strength, which in turn is noticeably lower compared with the other three groups. This suggests that welded joints with misalignment and incomplete root penetration are indeed the weakest of the four groups either due to the combination of the present defects or perhaps because of an additional unseen internal defect. From the other three diagrams, it can be concluded that the test specimens show very similar behaviour with nearly identical ultimate tensile strengths and considerable plasticity. The diagrams shows the most prominent yielding, with an easily distinguishable difference between the elastic and plastic regions. The diagrams are the most similar, having the same strain of around 9% and with a less obvious yield stress limit. |
topic |
welded joint finite element method (FEM) multiple defects stress concentration |
url |
https://www.mdpi.com/1996-1944/14/17/4832 |
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