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Andersson, O., Fahlström, K. & Melander, A. (2019). Experiments and efficient simulations of distortions of laser beam-welded thin-sheet close beam steel structures. Proceedings of the Institution of mechanical engineers. Part B, journal of engineering manufacture, 233(3), 787-796
Open this publication in new window or tab >>Experiments and efficient simulations of distortions of laser beam-welded thin-sheet close beam steel structures
2019 (English)In: Proceedings of the Institution of mechanical engineers. Part B, journal of engineering manufacture, ISSN 0954-4054, E-ISSN 2041-2975, Vol. 233, no 3, p. 787-796Article in journal (Refereed) Published
Abstract [en]

In this article, geometrical distortions of steel structures due to laser beam welding were analyzed. Two 700-mm-long U-beam structures were welded in overlap configurations: a double U-beam structure and a U-beam/flat structure. The structures were in different material combinations from mild steel to ultrahigh-strength steel welded with different process parameters. Different measures of distortions of the U-beam structures were evaluated after cooling. Significant factors of the welding process and the geometry of the structures were identified. Furthermore, welding distortions were modeled using two predictive finite element simulation models. The previously known shrinkage method and a newly developed time-efficient simulation method were evaluated. The new model describes the effects of expansion and shrinkage of the weld zone during welding and material plasticity at elevated temperatures. The new simulation method has reasonable computation times for industrial applications and improved agreement with experiments compared to the often used so-called shrinkage method.

Place, publisher, year, edition, pages
SAGE PUBLICATIONS LTD, 2019
Keywords
Laser beam welding, distortions, finite element simulations, ultrahigh-strength steel, thin-sheet structures
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:kth:diva-243934 (URN)10.1177/0954405417749625 (DOI)000456544300010 ()2-s2.0-85045056604 (Scopus ID)
Note

QC 20190313

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-13Bibliographically approved
Khodaee, A., Melander, A. & Haglund, S. (2018). The Effects of Blank Geometry on Gear Rolling for Large Gear Modules: Experiments and Finite Element Simulations. IEEE Access, 6, 33344-33352
Open this publication in new window or tab >>The Effects of Blank Geometry on Gear Rolling for Large Gear Modules: Experiments and Finite Element Simulations
2018 (English)In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 33344-33352Article in journal (Refereed) Published
Abstract [en]

Gear rolling is a forming process to produce gear wheels by plastic deformation. The advantage of the process is to eliminate the chip formation during production and also to improve the product properties since the non-metallic inclusions will be oriented along the cog surface and not perpendicular to it. The method has been developed in the past years for gear production for automobile application with modules up to 3 mm. The successful application of gear rolling in those cases raises the question regarding the feasibility of using cold rolling to manufacture gears with larger modules which can be used for heavy vehicles. In this paper, a gear wheel with normal module of 4 mm has been studied in order to investigate if such large modules can be manufactured by gear rolling. One of the issues in rolling of gears is the design of the blank geometry in order to obtain the right gear geometry after the rolling process. Blank shape modifications are necessary to control and to reduce the undesired shape deviations caused by the large plastic deformations in rolling. The blank modifications also help the process designer to control the forming force and torque. In this paper, the process has been modeled by finite element simulation and the influence of different blanks has been simulated. The validity of the FE model has been checked through several experiments. Both the numerical and experimental results revealed favorable blank modifications to apply for further developments of the gear rolling process.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
Keywords
Accuracy, gears, geometry, modeling, manufacturing processes
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-232651 (URN)10.1109/ACCESS.2018.2847737 (DOI)000438536100001 ()2-s2.0-85049091766 (Scopus ID)
Funder
VINNOVA, FFI SMART 2011-04445
Note

QC 20180730

Available from: 2018-07-31 Created: 2018-07-31 Last updated: 2018-07-31Bibliographically approved
Khodaee, A. & Melander, A. (2017). Evaluation of effects of geometrical parameters on density distribution in compaction of PM gears. In: Proceedings of the 20th International Esaform Conference on Material Forming: ESAFORM 2017. Paper presented at 20th International ESAFORM Conference on Material Forming, ESAFORM 2017, Dublin City University, Dublin, Ireland, 26 April 2017 through 28 April 2017. American Institute of Physics (AIP), 1896, Article ID 050006.
Open this publication in new window or tab >>Evaluation of effects of geometrical parameters on density distribution in compaction of PM gears
2017 (English)In: Proceedings of the 20th International Esaform Conference on Material Forming: ESAFORM 2017, American Institute of Physics (AIP), 2017, Vol. 1896, article id 050006Conference paper (Refereed)
Abstract [en]

The usage of powder metallurgy (PM) for manufacturing of transmission components in automotive industries has been studied by many researchers. PM components have become of interest in recent years due to advancements in post processing possibilities such as hot isostatic pressing (HIP). Still in many of the forming process routes for making components from PM materials, the compaction of the powder into green component is the first step. Compaction is required to put the powder into the near net shape of the desired component and it causes a density gradient in the body of the green component. Basically the friction between powder particles and between the powder particles and die walls are the well-known roots for such density gradients in the compacted component. Looking at forming of PM gears, the gradient in density is one of the most important roots of problems in the processing of PM gears as well. That is because making a gear with full density and no pores will be very costly if large density gradients exist in the green component. The purpose of this study is to find the possible relations between the gear geometry and the density gradients in the green component after compaction in addition to the friction effects. For this purpose several gears should be tested. To reduce the research costs, the finite element (FE) method is used. First a FE model of the compaction process is developed and verified. To investigate the relations between the density gradients and the gear parameters such as addendum diameter (da) and the face width (b) several gear geometries have been studied. The compaction of selected gears is simulated using the FE model. The simulations results which are the distribution of density in the green component are evaluated and discussed and conclusion are made based on them.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2017
Series
AIP Conference Proceedings, ISSN 0094-243X ; 1896
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-220428 (URN)10.1063/1.5008051 (DOI)2-s2.0-85037696974 (Scopus ID)9780735415805 (ISBN)
Conference
20th International ESAFORM Conference on Material Forming, ESAFORM 2017, Dublin City University, Dublin, Ireland, 26 April 2017 through 28 April 2017
Note

QC 20171220

Available from: 2017-12-20 Created: 2017-12-20 Last updated: 2018-01-29Bibliographically approved
Andersson, O., Budak, N., Melander, A. & Palmquist, N. (2017). Experimental measurements and numerical simulations of distortions of overlap laser-welded thin sheet steel beam structures. Welding in the World, 61(5), 927-934
Open this publication in new window or tab >>Experimental measurements and numerical simulations of distortions of overlap laser-welded thin sheet steel beam structures
2017 (English)In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 61, no 5, p. 927-934Article in journal (Refereed) Published
Abstract [en]

Distortions of mild steel structures caused by laser welding were analyzed. One thousand-millimeter U-beam structures were welded as overlap joints with different process parameters and thickness configurations. Final vertical and transverse distortions after cooling were measured along the U-beam. Significant factors, which affect distortions, were identified. Heat input per unit length, weld length, and sheet thickness showed a significant effect on welding distortions. Furthermore, the welding distortions were modeled using FE simulations. A simplified and computationally efficient simulation method was used. It describes the effect of shrinkage of the weld zone during cooling. The simulations show reasonable computation times and good agreement with experiments.

Place, publisher, year, edition, pages
SPRINGER HEIDELBERG, 2017
Keywords
Laser beam welding, Distortions, FE simulation, Volume shrinkage method, Mild steel
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-215469 (URN)10.1007/s40194-017-0496-z (DOI)000411060800006 ()2-s2.0-85027870009 (Scopus ID)
Note

QC 20171017

Available from: 2017-10-17 Created: 2017-10-17 Last updated: 2017-11-13Bibliographically approved
Andersson, O., Semere, D., Melander, A., Arvidsson, M. & Lindberg, B. (2016). Digitalization of Process Planning of Spot Welding in Body-in-white. In: Procedia CIRP: . Paper presented at 26th CIRP Design Conference, 2016, 15 June 2016 through 17 June 2016 (pp. 618-623). Elsevier
Open this publication in new window or tab >>Digitalization of Process Planning of Spot Welding in Body-in-white
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2016 (English)In: Procedia CIRP, Elsevier, 2016, p. 618-623Conference paper, Published paper (Refereed)
Abstract [en]

Process planning of spot welding for body-in-white automobile structures involves several experimental (physical) welding trials to set the process parameters. These experimental trials are crucial in ensuring the quality and efficiency of the process. However, due to the iterative nature of the work, running several experiments is costly and time consuming prolonging the overall development cost and time significantly. To minimize the cost and time, replacing the physical tests by digital (virtual) tests is an established approach although not often applied for spot welding. However, for a long chain of development process with several iterative loops, this is not a trivial task considering the availability of information and continuity of the work flow. This paper reports the work and results of an industrial case study conducted on spot welding of a body-in-white car pillar in a Swedish auto manufacturer. The aim of the study is to investigate and propose the necessary conditions required to replace a physical test by virtual tests in terms of validity and expedited execution of the process. Information sharing, knowledge reuse and streamlining the work flow have found to be critical condition for valid and rapid virtual tests.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
automotive, finite element simulation, numerical methods, Process planning, resistance spot welding, value stream mapping, Automobile bodies, Automobile manufacture, Finite element method, Iterative methods, Resistance welding, Testing, Virtual reality, Welding, Development process, Experimental trials, Finite element simulations, Industrial case study, Information sharing, Spot welding
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-195470 (URN)10.1016/j.procir.2016.05.082 (DOI)000387666600104 ()2-s2.0-84986593228 (Scopus ID)
Conference
26th CIRP Design Conference, 2016, 15 June 2016 through 17 June 2016
Note

QC 20161110

Available from: 2016-11-10 Created: 2016-11-03 Last updated: 2017-11-13Bibliographically approved
Strondl, A., Khodaee, A., Sundaram, M. V., Andersson, M., Melander, A., Heikkilä, I., . . . Ahlfors, M. (2016). Innovative powder based manufacturing of high performance gears. In: World PM 2016 Congress and Exhibition: . Paper presented at World Powder Metallurgy 2016 Congress and Exhibition, World PM 2016, Hamburg, Germany, 9 October 2016 through 13 October 2016. European Powder Metallurgy Association (EPMA)
Open this publication in new window or tab >>Innovative powder based manufacturing of high performance gears
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2016 (English)In: World PM 2016 Congress and Exhibition, European Powder Metallurgy Association (EPMA) , 2016Conference paper (Refereed)
Abstract [en]

There are strong driving forces towards high-performance gear wheels which can handle higher engine outputs, or allow more compact designs of transmissions. Today the performance and life of conventionally manufactured gear wheels are limited by factors such as inhomogeneous microstructure and distribution of inclusions. Powder metallurgy (PM) can solve some of these problems but has so far had limitations caused by porosity. In this paper a cost effective way to eliminate porosity by HIP-ing without canister has been evaluated with encouraging results. Parameters such as powder particle size, lubricant and double pressing have been evaluated in the PM route in order to get a gas tight surface enabling effective post HIP-ing. So far double pressing has given promising results. Challenges such as open porosity, surface porosity and inclusions are addressed in the paper.

Place, publisher, year, edition, pages
European Powder Metallurgy Association (EPMA), 2016
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:kth:diva-219676 (URN)2-s2.0-85035359470 (Scopus ID)9781899072484 (ISBN)
Conference
World Powder Metallurgy 2016 Congress and Exhibition, World PM 2016, Hamburg, Germany, 9 October 2016 through 13 October 2016
Funder
VINNOVA, 2013-05594
Note

QC 20171212

Available from: 2017-12-12 Created: 2017-12-12 Last updated: 2017-12-12Bibliographically approved
Ratanathavorn, W. & Melander, A. (2015). Dissimilar joining between aluminium alloy (AA 6111) and thermoplastics using friction stir welding. Science and technology of welding and joining, 20(3), 222-228
Open this publication in new window or tab >>Dissimilar joining between aluminium alloy (AA 6111) and thermoplastics using friction stir welding
2015 (English)In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 20, no 3, p. 222-228Article in journal (Refereed) Published
Abstract [en]

In this work, friction stir welding was used to produce shear overlap joints between aluminium and a thermoplastic (AA 6111 to polyphenylene sulphide). The process uses the friction stir welding tool to create metallic chips which merge with the molten thermoplastic to form a joint. No special surface pretreatment is required before joining. Cross-sections show mechanical locking between the chipped polymer filled zone and the surrounding aluminium sheet. The effects of joining parameters such as rotational speed, translational speed and distance to backing were investigated in relation to the joint strength and failure mode. Optimum speeds and backing distances could be identified. The joint strength is dominated by mechanical interlocking between the chip and polymer filled zone and the aluminium sheet.

Keywords
Dissimilar joining, Friction stir welding, Aluminium alloy, Plastics
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-166349 (URN)10.1179/1362171814Y.0000000276 (DOI)000352313200006 ()2-s2.0-84924987840 (Scopus ID)
Funder
VINNOVA, 2010-01982
Note

QC 20150511

Available from: 2015-05-11 Created: 2015-05-07 Last updated: 2017-12-04Bibliographically approved
Ratanathavorn, W. & Melander, A. (2015). Dissimilar joining between alumnium alloy AA6111 and thermoplastics using friction stir weldiing. Science and technology of welding and joining
Open this publication in new window or tab >>Dissimilar joining between alumnium alloy AA6111 and thermoplastics using friction stir weldiing
2015 (English)In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936Article in journal (Refereed) Accepted
National Category
Engineering and Technology
Research subject
SRA - Production
Identifiers
urn:nbn:se:kth:diva-161928 (URN)
Note

QP 201503

Available from: 2015-03-19 Created: 2015-03-19 Last updated: 2017-12-04Bibliographically approved
Fahlström, K., Andersson, O., Todal, U. & Melander, A. (2015). Minimization of distortions during Laser Welding of Ultra High Strength Steel. Paper presented at ICALEO 2014, 33rd International Congress on Applications of Lasers & Electro-Optics, October 19-23, San Diego, USA. Journal of laser applications, 27(S2), Article ID S29011.
Open this publication in new window or tab >>Minimization of distortions during Laser Welding of Ultra High Strength Steel
2015 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 27, no S2, article id S29011Article in journal (Refereed) Published
Abstract [en]

Ultra high strength steels are frequently used within the automotive industry for several components. Welding of these components is traditionally done by resistance spot welding, but to get further productivity and increased strength, laser welding has been introduced in the past decades. Fusion welding is known to cause distortions due to built in stresses in the material. The distortions result in geometrical issues during assembly which become the origin of low joint quality due to gaps and misfits. U-beam structures of boron steel simulating B-pillars have been welded with laser along the flanges. Welding parameters and clamping have been varied to create different welding sequences and heat input generating a range of distortion levels. The distortions have been recorded dynamically with an optical measurement system during welding. In addition, final distortions have been measured by a digital Vernier caliper. The combined measurements give the possibility to evaluate development, occurrence, and magnitude of distortions with high accuracy. Furthermore, section cuts have been analyzed to assess joint geometry and metallurgy. The results show that final distortions appear in the range of 0–8 mm. Distortions occur mainly transversely and vertically along the profile. Variations in heat input show clear correlation with the magnitude of distortions and level of joint quality. A higher heat input in general generates a higher level of distortion with the same clamping conditions. Section cuts show that weld width and penetration are significantly affected by welding heat input. The present study identifies parameters which significantly influence the magnitude and distribution of distortions. Also, effective measures to minimize distortions and maintain or improve joint quality have been proposed. Finally, transient finite element (FE) simulations have been presented which show the behavior of the profiles during the welding and unclamping process.

Keywords
ultra high strength steel, boron steel, laser welding, distortions, finite element simulations
National Category
Mechanical Engineering
Research subject
SRA - Production
Identifiers
urn:nbn:se:kth:diva-161927 (URN)10.2351/1.4906468 (DOI)000350544500020 ()2-s2.0-84943625500 (Scopus ID)
Conference
ICALEO 2014, 33rd International Congress on Applications of Lasers & Electro-Optics, October 19-23, San Diego, USA
Note

QC 20150326

Available from: 2015-03-19 Created: 2015-03-19 Last updated: 2017-12-04Bibliographically approved
Andersson, O. & Melander, A. (2015). Prediction and verification of resistance spot welding results of ultra high strength steels through FE simulations. Modeling and Numerical Simulation of Material Science, 5, 26-37
Open this publication in new window or tab >>Prediction and verification of resistance spot welding results of ultra high strength steels through FE simulations
2015 (English)In: Modeling and Numerical Simulation of Material Science, E-ISSN 2164-5353, Vol. 5, p. 26-37Article in journal (Refereed) Published
Abstract [en]

Resistance spot welding (RSW) is the most common welding method in automotive engineering due to its low cost and high ability of automation. However, physical weldability testing is costly, time consuming and dependent of supplies of material and equipment. Finite Element (FE) simulations have been utilized to understand, verify and optimize manufacturing processes more efficiently. The present work aims to verify the capability of FE models for the RSW process by comparing simulation results to physical experiments for materials used in automotive production, with yield strengths from approximately 280 MPa to more than 1500 MPa. Previous research has mainly focused on lower strength materials. The physical weld results were assessed using destructive testing and an analysis of expulsion limits was also carried out. Extensive new determination of material data was carried out. The material data analysis was based on physical testing of material specimens, material simulation and comparison to data from literature. The study showed good agreement between simulations and physical testing. The mean absolute error of weld nugget size was 0.68 mm and the mean absolute error of expulsion limit was 1.10 kA.

National Category
Engineering and Technology
Research subject
SRA - Production
Identifiers
urn:nbn:se:kth:diva-161930 (URN)10.4236/mnsms.2015.51003 (DOI)
Note

QC 20150331

Available from: 2015-03-19 Created: 2015-03-19 Last updated: 2019-08-28Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-6061-662X

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