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Mansour, R., Zhu, J., Edgren, M. & Barsoum, Z. (2019). A probabilistic model of weld penetration depth based on process parameters. The International Journal of Advanced Manufacturing Technology, 105(1-4), 499-514
Open this publication in new window or tab >>A probabilistic model of weld penetration depth based on process parameters
2019 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 105, no 1-4, p. 499-514Article in journal (Refereed) Published
Abstract [en]

In welded structures using robotized metal active gas (MAG) welding, unwanted variation in penetration depth is typically observed. This is due to uncertainties in the process parameters which cannot be fully controlled. In this work, an analytical probabilistic model is developed to predict the probability of satisfying a target penetration, in the presence of these uncertainties. The proposed probabilistic model incorporates both aleatory process parameter uncertainties and epistemic measurement uncertainties. The latter is evaluated using a novel digital tool for weld penetration measurement. The applicability of the model is demonstrated on fillet welds based on an experimental investigation. The studied input process parameters are voltage, current, travel speed, and torch travel angle. The uncertainties in these parameters are modelled using adequate probability distributions and a statistical correlation based on the volt-ampere characteristic of the power source. Using the proposed probabilistic model, it is shown that a traditional deterministic approach in setting the input process parameters typically results in only a 50% probability of satisfying a target penetration level. It is also shown that, using the proposed expressions, process parameter set-ups satisfying a desired probability level can be simply identified. Furthermore, the contribution of the input uncertainties to the variation of weld penetration is quantified. This work paves the way to make effective use of the robotic welding, by targeting a specified probability of satisfying a desired weld penetration depth as well as predicting its variation.

Place, publisher, year, edition, pages
SPRINGER LONDON LTD, 2019
Keywords
Weld penetration depth, Process variables, MAG welding, Aleatory uncertainty, Epistemic uncertainty
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:kth:diva-266394 (URN)10.1007/s00170-019-04110-5 (DOI)000495396000028 ()2-s2.0-85070292064 (Scopus ID)
Note

QC 20200402

Available from: 2020-04-02 Created: 2020-04-02 Last updated: 2020-04-02Bibliographically approved
Zhu, J., Khurshid, M. & Barsoum, Z. (2019). Accuracy of computational welding mechanics methods for estimation of angular distortion and residual stresses. Welding in the World, 63(5), 1391-1405
Open this publication in new window or tab >>Accuracy of computational welding mechanics methods for estimation of angular distortion and residual stresses
2019 (English)In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, no 5, p. 1391-1405Article in journal (Refereed) Published
Abstract [en]

This study estimates the angular distortion and residual stresses due to welding using the following methodologies: thermo-elastic-plastic, inherent strain (local-global), and substructuring on two types of welded joints (T-type fillet weld and butt weld). The numerical results are compared with the experimental measurements and these methodologies are evaluated in terms of accuracy and computational time. In addition, the influence of welding sequence on distortion and transverse residual stresses has been studied numerically by implementing the thermo-elastic-plastic and inherent strain (local-global) methods on the T-type fillet weld. For the T-type fillet weld, the estimated angular distortion from these methods is much the same and in good agreement with the experimental measurements. For the butt weld, the angular distortion calculated by the inherent strain (local-global) method is largely underestimated. In order to gain a better understanding of where the underestimation of angular distortion in the inherent strain (local-global) method comes from, the study discusses the influence of block length and welding speed on angular distortion. It is found that for long weld length or slow welding speed, activating the plastic strain gradually by dividing the weld bead into an appropriate number of blocks can reduce the level of underestimation of angular distortion.

Place, publisher, year, edition, pages
SPRINGER HEIDELBERG, 2019
Keywords
Angular distortion, Residual stresses, Thermo-elastic-plastic, Inherent strain, Substructuring
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:kth:diva-259424 (URN)10.1007/s40194-019-00746-9 (DOI)000482459300020 ()2-s2.0-85067672268 (Scopus ID)
Note

QC 20190924

Available from: 2019-09-24 Created: 2019-09-24 Last updated: 2019-09-24Bibliographically approved
Zhu, J., Khurshid, M. & Barsoum, Z. (2019). Assessment of computational weld mechanics concepts for estimation of residual stresses in welded box structures. In: Moreira, PMGP Tavares, PJS (Ed.), 3rd International Conference on Structural Integrity, (ICSI 2019): . Paper presented at 3rd International Conference on Structural Integrity, ICSI 2019; Funchal, Madeira; Portugal; 2 September 2019 through 5 September 2019 (pp. 704-711). Elsevier, 17
Open this publication in new window or tab >>Assessment of computational weld mechanics concepts for estimation of residual stresses in welded box structures
2019 (English)In: 3rd International Conference on Structural Integrity, (ICSI 2019) / [ed] Moreira, PMGP Tavares, PJS, Elsevier, 2019, Vol. 17, p. 704-711Conference paper, Published paper (Refereed)
Abstract [en]

In this study finite element simulation approaches (lumping and prescribed temperature) are implemented to study residual stress distribution in a welded box type structure. This component is a vital part in several load carrying structural applications and the residual stresses are important to quantify from a structural integrity point of view. The thermal history from simulations has been verified with experimental measurements. The residual stresses at the weld toe side were measured, using X-ray diffraction technique. It is shown that a similar trend of residual stress state was captured by the simulation, compared to experimental measurements. The estimated residual stresses from the cases of welds with full penetration and partial penetration are slightly different along the crack path. Compressive residual stress was near the area of both weld toe and root while tensile residual stress was in the center of the weld with the magnitude up to 820 MPa. Moreover, a sub model of the welded box type structure is studied using the following computational weld mechanics concepts: Thermo -elastic -plastic, lumping and prescribed temperature, in order to assess the computational time and the magnitude of estimated residual stresses.

Place, publisher, year, edition, pages
Elsevier, 2019
Series
Procedia Structural Integrity, ISSN 2452-3216 ; 17
Keywords
Finite element method, residual stresses, welding simulation, welded box structures
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-266724 (URN)10.1016/j.prostr.2019.08.094 (DOI)000505162900093 ()2-s2.0-85074669361 (Scopus ID)
Conference
3rd International Conference on Structural Integrity, ICSI 2019; Funchal, Madeira; Portugal; 2 September 2019 through 5 September 2019
Note

QC 20200117

Available from: 2020-01-17 Created: 2020-01-17 Last updated: 2020-01-17Bibliographically approved
Stenberg, T., Barsoum, Z., Hedlund, J. & Josefsson, J. (2019). Development of a computational fatigue model for evaluation of weld quality. Welding in the World, 63(6), 1771-1785
Open this publication in new window or tab >>Development of a computational fatigue model for evaluation of weld quality
2019 (English)In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, no 6, p. 1771-1785Article in journal (Refereed) Published
Abstract [en]

The current study focuses on the development of a predictive model for assessing the fatigue life of welded joints based on measured weld geometry and applied load. Two different materials (S355 and S960) and two different material thicknesses (2 mm and 8 mm) were considered. Experiments on cruciform joints were conducted to evaluate the fatigue performance for different types of weld geometries. A computational model based on FEM and linear elastic fracture mechanics was developed and adapted to fit the experimental results using optimization and surrogate models. It is observed that the general fatigue behavior differs for the different materials for the same variation in geometry. The fatigue performance depends on a combination of geometrical parameters. The use of FAT curves according to the weld quality systems, e.g., ISO 5817, is insufficient to describe fatigue properties for welds in thin high strength steel, and different geometries within different weld quality levels can give the same fatigue behavior. It is also concluded that the developed computational model is suitable for further development of weld quality systems.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Computational model, Fatigue, Fracture mechanics, Weld quality, Welded joints, Computation theory, Computational methods, Geometry, High strength steel, Quality control, Welding, Welds, Different geometry, Fatigue performance, Fatigue properties, Linear elastic fracture mechanics, Material thickness, Predictive modeling, Fatigue of materials
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-263276 (URN)10.1007/s40194-019-00777-2 (DOI)000501904600021 ()2-s2.0-85069507812 (Scopus ID)
Note

QC 20191105

Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2020-02-19Bibliographically approved
Edgren, M., Barsoum, Z., Åkerlind, K. & Al-Emrani, M. (2019). Evaluation of HFMI as a Life Extension Technique for Welded Bridge Details. In: Lefebvre, F Cetim, PS (Ed.), Fatigue Design 2019, International Conference on Fatigue Design, 8th Edition: . Paper presented at 8th International Conference on Fatigue Design (Fatigue Design), NOV 20-21, 2019, Cetim, France (pp. 73-80). Elsevier
Open this publication in new window or tab >>Evaluation of HFMI as a Life Extension Technique for Welded Bridge Details
2019 (English)In: Fatigue Design 2019, International Conference on Fatigue Design, 8th Edition / [ed] Lefebvre, F Cetim, PS, Elsevier, 2019, p. 73-80Conference paper, Published paper (Refereed)
Abstract [en]

In this current study, HFMI technique is used to study the possibility to extend the fatigue life of pre-fatigued flange gusset welds typically found in girder bridges. The results from the study are also compared with results found in the literature for other more conventional techniques for retrofitting, e.g. cut-outs. The study also aims to investigate if the IIW HFMI recommendations could be applied for existing steel structures and that equal fatigue strength improvement could be claimed for prefatigued structures. Furthermore, new recommendations for structural hot spot stress type B are suggested for HFMI treated welds, applicable to flange guest welds. The results indicate that the HFMI could be used for welded bridge details rehabilitation as a competing technology with conventional cut-out. Furthermore, the results indicate that the IIW recommendations for HFMI fatigue strength improvement could also be applied for pre-fatigued welded details.

Place, publisher, year, edition, pages
Elsevier, 2019
Series
Procedia Structural Integrity, ISSN 2452-3216 ; 19
Keywords
Welded joints, fatigue, Life extension, improvement technique, HFMI
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-272874 (URN)10.1016/j.prostr.2019.12.009 (DOI)000525951600008 ()2-s2.0-85081618104 (Scopus ID)
Conference
8th International Conference on Fatigue Design (Fatigue Design), NOV 20-21, 2019, Cetim, France
Note

QC 20200601

Available from: 2020-06-01 Created: 2020-06-01 Last updated: 2020-06-01Bibliographically approved
Baumgartner, J., Yıldırım, H. C. & Barsoum, Z. (2019). Fatigue strength assessment of TIG-dressed welded steel joints by local approaches. International Journal of Fatigue, 126, 72-78
Open this publication in new window or tab >>Fatigue strength assessment of TIG-dressed welded steel joints by local approaches
2019 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 126, p. 72-78Article in journal (Refereed) Published
Abstract [en]

Fatigue strength assessment methods by local approaches are widely used in the literature. This paper provides a comprehensive evaluation of published data for welded steel joints improved by TIG dressing methods. Fatigue classes for the local assessment methods with the available fatigue data are recommended. The available fatigue data extracted for transverse non-load carrying welds, cruciform joints as well as butt joints. In total, 17 published test series of weld details with various yield strengths and stress ratios are presented. Fatigue strength assessment is performed by considering the weld profile geometry within Finite Element models and taking the resulting stress gradients as basis for the evaluation. In addition, the influence of the steel grade is included. The most reliable results are derived by using the critical distance approach. Fatigue classes and critical distances are recommended as a result of the evaluations.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Fatigue design, Finite elements, Size effects, TIG-dressing, Welded joints, Finite element method, Microalloyed steel, Welding, Welds, Yield stress, Comprehensive evaluation, Cruciform joints, Fatigue strength assessment, Local approaches, Reliable results, TIG dressings, Fatigue of materials
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-252449 (URN)10.1016/j.ijfatigue.2019.04.038 (DOI)000472688800008 ()2-s2.0-85064954298 (Scopus ID)
Note

QC 20190715

Available from: 2019-07-15 Created: 2019-07-15 Last updated: 2019-07-29Bibliographically approved
Ahola, A., Bjork, T. & Barsoum, Z. (2019). Fatigue strength capacity of load-carrying fillet welds on ultra-high-strength steel plates subjected to out-of-plane bending. Engineering structures, 196, Article ID UNSP 109282.
Open this publication in new window or tab >>Fatigue strength capacity of load-carrying fillet welds on ultra-high-strength steel plates subjected to out-of-plane bending
2019 (English)In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 196, article id UNSP 109282Article in journal (Refereed) Published
Abstract [en]

Weld root fatigue strength capacity is an important design criterion in load-carrying (LC) fillet welded joints subjected to cyclic loads. This paper elaborates on the weld root fatigue strength capacity of fillet welded LC joints made of ultra-high-strength steel (UHSS) and subjected to out-of-plane bending. Experimental fatigue tests are carried out using constant amplitude loading with an applied stress ratio of R = 0.1 with both pure axial, i.e. DOB = 0 (degree of bending, bending stress divided by total stress) and bending, i.e. DOB = 1.0, load conditions. The applicability of different approaches - nominal weld stress, effective notch stress concepts, and 2D linear elastic fracture mechanics (LEFM) - for the fatigue strength assessment of weld root capacity is evaluated. Furthermore, a parametric LEFM analysis is used to evaluate the effect of weld penetration on the root fatigue strength capacity in axial and bending loading. The results indicate that in the case of bending, nominal weld stress can be calculated using the linear stress distribution over the joint section and FAT36 as a reference curve. In the bending loading, for the joints failing from the weld toe, a mean fatigue strength of up to 185 MPa in the nominal stress system was achieved, indicating that the reference curve FAT63 is overly conservative. The ENS concept with FAT225 seemed to be slightly unconservative for assessing the root fatigue strength capacity. LEFM analyses revealed that in the case of increasing weld penetration and bending loading, weld root fatigue strength capacity seemed to correlate with the nominal weld stress calculated using effective weld throat thickness, while in axial loading, weld stress should be calculated using external throat thickness summed with penetration length.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2019
Keywords
Fatigue assessment, Welded joints, Weld root fatigue strength, Bending, Ultra-high-strength steel, Load-carrying joint
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-259412 (URN)10.1016/j.engstruct.2019.109282 (DOI)000482518700008 ()2-s2.0-85067085616 (Scopus ID)
Note

QC 20190924

Available from: 2019-09-24 Created: 2019-09-24 Last updated: 2019-09-24Bibliographically approved
Cheemakurthy, H., Zhang, M., Garme, K. & Barsoum, Z. (2019). Nonlinear Finite Element Analysis of Inland-Waterway Barge in Fresh Water Ice Conditions. In: Proceedings of the Annual International Offshore and Polar Engineering Conference: Proceedings of The Twenty-ninth (2019) International OCEAN AND POLAR ENGINEERING CONFERENCE. Paper presented at Annual International Ocean (Offshore) and Polar Engineering Conference (ISOPE),Honolulu, Hawaii, USA, June 16−21, 2019 (pp. 799-806). Honolulu, Hawaii, 1
Open this publication in new window or tab >>Nonlinear Finite Element Analysis of Inland-Waterway Barge in Fresh Water Ice Conditions
2019 (English)In: Proceedings of the Annual International Offshore and Polar Engineering Conference: Proceedings of The Twenty-ninth (2019) International OCEAN AND POLAR ENGINEERING CONFERENCE, Honolulu, Hawaii, 2019, Vol. 1, p. 799-806Conference paper, Published paper (Refereed)
Abstract [en]

There has been an increased awareness of the benefits of utilizing inland waterways (IWW) from a transport efficiency and an emission control point of view. However, due to presence of ice in water bodies, vessels designed for non-ice river operations cannot operate during the winter months. This paper analyses a grillage representative of barge’s bow region using non-linear finite element analysis (NL FEA) and assesses survivability in comparison with load limits prescribed by latest Finnish Swedish Ice Class Rules (FSICR) 2017 rules, International Association of Classification Societies (IACS) Polar Cass 6 (PC6) rules and simplified plastic collapse limit states calculated by Daley (2002). The NLFEA study included strength contributions from strain hardening and membrane stress and it was found that the limit state described by rupture stress was significantly larger. It was found that allowance for plasticity can reduce structural scantling requirements for fresh water ice operating vessels. The study also validated latest FSIRCR 2017 requirements.

Place, publisher, year, edition, pages
Honolulu, Hawaii: , 2019
Keywords
Fresh water ice, Inland Waterways, Sweden, FSICR Rules 2017, IACS PC6, Non-Linear FEA, plasticity, Bow structural design, Inland waterway river barge, operations in ice. (PDF) Nonlinear Finite Element Analysis of Inland-Waterway Barge in Fresh Water Ice Conditions
National Category
Other Engineering and Technologies
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-266338 (URN)10.6084/m9.figshare.11117636 (DOI)2-s2.0-85078844282 (Scopus ID)978-1-880653-85-2 (ISBN)
Conference
Annual International Ocean (Offshore) and Polar Engineering Conference (ISOPE),Honolulu, Hawaii, USA, June 16−21, 2019
Note

QC 20200110

Available from: 2020-01-07 Created: 2020-01-07 Last updated: 2020-05-25Bibliographically approved
Afshari, D., Mirzaahamdi, S. & Barsoum, Z. (2019). Residual Stresses in Resistance Spot Welded AZ61 Mg Alloy. CMES - Computer Modeling in Engineering & Sciences, 118(2), 275-290
Open this publication in new window or tab >>Residual Stresses in Resistance Spot Welded AZ61 Mg Alloy
2019 (English)In: CMES - Computer Modeling in Engineering & Sciences, ISSN 1526-1492, E-ISSN 1526-1506, Vol. 118, no 2, p. 275-290Article in journal (Refereed) Published
Abstract [en]

The use of magnesium alloys has been rapidly increased due to their ability to maintain high strengths at light weights. However weldability of steels and aluminum alloys by using resistance spot weld (RSW) process is a major issue, because it cannot be directly utilized for magnesium alloys. In this study, a structural-thermal-electrical finite element (FE) model has been developed to predict the distribution of residual stresses in RSW AZ61 magnesium alloy. Thermophysical and thermomechanical properties of AZ61 magnesium alloy have been experimentally determined, and have been used in FE model to increase the accuracy of the model. X-ray diffraction (XRD) technique has been utilized to measure the residual stresses in welded samples, and its results have been used to validate the FE model. Comparison study shows that the results obtained by using FE model have a good agreement with the experimental XRD data. In specific, the results show that the maximum tensile residual stress occurs at the weld center while decreases towards the nugget edge. In addition, the effects of welding parameters such as electrical current, welding time, and electrode force have been investigated on the maximum tensile residual stress. The results show that the tensile residual stress in welded joints rises by increasing the electrical current; however, it declines by prolonging the welding time as well as increasing the electrode force.

Place, publisher, year, edition, pages
TECH SCIENCE PRESS, 2019
Keywords
Resistance spot weld, AZ61 mg alloy, residual stresses, finite element model, x-ray diffraction
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-246293 (URN)10.31614/cmes.2019.03880 (DOI)000459391600002 ()2-s2.0-85063015035 (Scopus ID)
Note

QC 20190325

Available from: 2019-03-25 Created: 2019-03-25 Last updated: 2019-05-13Bibliographically approved
Barsoum, I., Barsoum, Z. & Islam, M. D. (2019). Thermomechanical Evaluation of the Performance and Integrity of a HDPE Stub-End Bolted Flange Connection. Journal of Pressure Vessel Technology-Transactions of the ASME, 141(5), Article ID 051206.
Open this publication in new window or tab >>Thermomechanical Evaluation of the Performance and Integrity of a HDPE Stub-End Bolted Flange Connection
2019 (English)In: Journal of Pressure Vessel Technology-Transactions of the ASME, ISSN 0094-9930, E-ISSN 1528-8978, Vol. 141, no 5, article id 051206Article in journal (Refereed) Published
Abstract [en]

In this study, the integrity of a manhole structure made of a 78 in. high density polyethylene (HDPE) stub-end, steel ring, and blind flange, sealed with a compressed nonasbestos fiber (CNAF) gasket is investigated by means of a parametric finite element analysis (FEA). A coupled thermomechanical nonlinear FEA model is built, comprising of a heat transfer and a structural model, which allows modeling the complex thermal and mechanical loads and their interactions present during the operation of the manhole. The temperature-dependent elastic-plastic HDPE material constitutive behavior and the temperature-dependent nonlinear response of the CNAF gasket are accounted for in the model. Factors influencing the performance and integrity of the manhole such as stud-bolt pretorque level (T-b), internal pressure (P-i), and outer temperature (T-o) are considered. Based on the results, the integrity and performance of the structure are assessed in view of a leakage through the gasket criterion and a yielding of the HDPE stub-end criterion. The FEA results reveal that both T-b, P-i, and T-o significantly influence the performance (i.e., leakage) of the gasket and the integrity (i.e., yielding) of the HDPE stubend. At 40 degrees C, it is possible to find a safe operational window for a range of T-b and P-i values, where no leakage through the gasket or yielding of the stub-end occurs. However, as the temperature is increased this safe operational window decreases considerably, and at 80 degrees C safe operation cannot be guaranteed where leakage, yielding, or both simultaneously, will lead to loss in performance and integrity of the manhole structure.

Place, publisher, year, edition, pages
ASME, 2019
Keywords
HDPE, bolted flange, stub-end, gasket, finite element analysis, leakage, yielding, failure assessment chart
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-261297 (URN)10.1115/1.4043844 (DOI)000485710100007 ()2-s2.0-85069147256 (Scopus ID)
Note

QC 20191008

Available from: 2019-10-08 Created: 2019-10-08 Last updated: 2019-11-26Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-4180-4710

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