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  • 1.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. KTH, Centres, XPRES, Excellence in production research.
    Budak, Nesrin
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. KTH, Centres, XPRES, Excellence in production research.
    Palmquist, Niclas
    Experimental measurements and numerical simulations of distortions of overlap laser-welded thin sheet steel beam structures2017In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 61, no 5, p. 927-934Article in journal (Refereed)
    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.

  • 2.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Budak, Nesrin
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Palmqvist, Niclas
    Distortions of overlap laser welded thin sheet mild steel beam structuresManuscript (preprint) (Other academic)
  • 3.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    General regression model for prediction of spot weld sizes2011In: International Congress on Advances in Welding Science and Technology for Construction, Energy and Transportation Systems, 2011Conference paper (Other academic)
  • 4.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    General regression models for prediction of spot weld sizes2011In: International congress on advances in welding science and technology for construction energy and transportation systems, IIW Congress, 2011, Istambul, Turkey, 2011Conference paper (Refereed)
  • 5.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Statistical Analysis of Variations in Resistance Spot Weld Results in Laboratory and Production EnvironmentManuscript (preprint) (Other academic)
  • 6.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Statistical analysis of variations in resitance spot weld results in laboratory and productionIn: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936Article in journal (Other academic)
  • 7.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Statistical Analysis of variations of resistance spot weld nugget sizes2011In: IIW International Conference on Global Trends in Joining, Cuttin and Surfacing Technology, Chennai, India 2011, IIW, 2011, p. 870-875Conference paper (Refereed)
  • 8.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Verification of the capability of resistance spot welding simulationManuscript (preprint) (Other academic)
  • 9.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Verification of the Capability of Resistance Spot Welding Simulation for automotive process planningManuscript (preprint) (Other academic)
  • 10.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Fahlström, Karl
    Experiments and efficient simulations of distortions of laser beam welded thin sheet closed beam steel structuresIn: Article in journal (Refereed)
  • 11.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Fahlström, Karl
    Verification and evaluation of simulation methods of laser beam welding of thin sheet steel structuresIn: Article in journal (Refereed)
  • 12.
    Andersson, Oscar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Semere, Daniel
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. Swerea KIMAB, Sweden.
    Arvidsson, M.
    Lindberg, Bengt
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Digitalization of Process Planning of Spot Welding in Body-in-white2016In: Procedia CIRP, Elsevier, 2016, p. 618-623Conference 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.

  • 13. Collin, T
    et al.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    FEM study of fatigue response of 3-sheet spot welded joints2006In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 4, no 77, p. 292-296Article in journal (Refereed)
    Abstract [en]

    The commercial software used for predicting fatigue strength for load-carrying spot welds in sheet structures, like car bodies, is mainly developed for two-sheet joints. The purpose of this work was to study the fatigue properties of three-sheet spot welded joints with a dimensioning method used in the automotive industry and to compare such computational results to those obtained from a more accurate method and to experimental data. Eleven three-sheet, single spot welded specimens were studied using a structural stress approach, followed by shell element simulations, similar to those used in commercial software. These results were compared to calculations based on fine meshed solid element models. Fracture mechanics was used to evaluate the loading conditions at the spot welds. Comparison between the results from the different methods and experimental results for three shear loaded specimens, consisting of triple sheets, found in literature showed good correlation. The shell element method in shear loaded cases gives stress intensities within +35% to -5% of the solid element method results. In peel loaded cases the results differ up to -60%, an under-estimation that leads to an increase of estimated fatigue life up to 65 times.

  • 14.
    Fahlkrans, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Scania CV, Stockholm, Sweden.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Swerea KIMAB, Stockholm, Sweden.
    Gårdstam, Johannes
    Swerea KIMAB, Stockholm, Sweden.
    Haglund, Sven
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Swerea KIMAB, Stockholm, Sweden.
    Straightening of induction hardened shafts: influence on fatigue strength and residual stress2012In: HTM Journal of Heat Treatment and Materials, ISSN 1867-2493, Vol. 67, no 3, p. 179-187Article in journal (Refereed)
    Abstract [en]

    Straightening of distorted components after heat treatment is often a necessary operation. The straightening operation leads to local plasticization, which is affecting the residual stress state, the hardness, and ultimately the fatigue strength of the component. The present study evaluates the influence of a straightening operation on fatigue strength and on the residual stress state of induction hardened shafts of steel 42CrMo4. A simplified FEM model was formulated. The model showed that the residual stress state was asymmetric along the circumference of a straightened shaft. Fatigue testing was performed in three point bending and showed that the fatigue strength was reduced by up to some 20 % by heavy straightening. A fracture mechanics model for fatigue crack growth and arrest was developed. The model could be used to predict the fatigue strength of a straightened shaft provided that the residual stress state was known.

  • 15.
    Fahlkrans, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Scania CV, Stockholm, Sweden.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Swerea KIMAB, Stockholm, Sweden.
    Haglund, Sven
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Swerea KIMAB, Stockholm, Sweden.
    Gas Quench Rate after Low Pressure Carburizing and its Influence on Fatigue Properties of Gears2013In: HTM - Journal of Heat Treatment and Materials, ISSN 1867-2493, Vol. 68, no 6, p. 239-245Article in journal (Refereed)
    Abstract [en]

    Process modifications of the gas quench sequence for low pressure carburized gears can increase the performance of up to 22 %, compared to direct gas quenching. Several test series were made with different interruptions of the gas quenching sequence, near the martensite start temperature Ms. The quench interruption resulted in an increase in magnitude of compressive residual stress which was attributed to temperature homogenization and rearrangement of local stresses. The increased fatigue strength was a result of the combination of enhancement of the compressive residual stress state, and of mechanical stabilization of austenite.

  • 16.
    Fahlkrans, Johan
    et al.
    Scania CV, Sweden.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Swerea KIMAB, Stockholm, Sweden.
    Johansson, Krister
    Scania CV, Stockholm, Sweden.
    Haglund, Sven
    Swerea KIMAB, Sweden.
    Hosseini, Seyed B.
    Swerea IVF, Stockholm, Sweden.
    Influence of tempering on contact fatigue2011In: International Journal of Microstructure and Materials Properties, ISSN 1741-8410, E-ISSN 1741-8429, Vol. 6, no 6, p. 465-478Article in journal (Refereed)
    Abstract [en]

    Most components are tempered after heat treatment operations such as case hardening or induction hardening. The common opinion is that the martensitic structure after heat treatment is too brittle and tempering is necessary to increase toughness.

    Tempering is an additional operation which leads to increased costs by energy, handling, and investments. Eliminating tempering from the heat treatment process leads to increased productivity, energy savings, and lowered environmental impact.

    Two carburised steels, Ovako 253A (?EN 22NiCrMo12-5F mod. A) and EN 20NiCrMo2 (SAE 8620, SS2506), were tested for contact fatigue resistance in a roller to roller rig. The tested samples were characterised with respect to amount of fatigue damage, residual stress, amount of retained austenite and hardness. The objective was to determine if tempering is always necessary after a heat treatment operation.

    The contact fatigue tests show that tempering results in lower contact fatigue resistance. Further, fatigue cracks were found to have initiated in different ways between tempered and untempered steel.

  • 17.
    Fahlström, Karl
    et al.
    Swerea KIMAB, Sweden.
    Andersson, Oscar
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. KTH, Centres, XPRES, Excellence in production research. Volvo Cars, Sweden.
    Todal, Urban
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research.
    Minimization of distortions during Laser Welding of Ultra High Strength Steel2015In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 27, no S2, article id S29011Article in journal (Refereed)
    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.

  • 18.
    Fahlström, Karl
    et al.
    Swerea KIMAB.
    Andersson, Oscar
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. KTH, Centres, XPRES, Excellence in production research. Volvo Cars Corporation.
    Todal, Urban
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Swerea KIMAB.
    Lars-Erik, Svensson
    Högskolan Väst.
    Leif, Karlsson
    Högskolan Väst.
    Distortion Analysis in laser Welding of Ultra High Strength Steel2014In: Proc 6th International Swedish Production symposium 2014, 2014Conference paper (Refereed)
    Abstract [en]

    Due to increased demands on reduced weight in automotive industries, the use of ultra high strength steels (UHSS) has increased. When laser welding UHSS ssheets, heating and cooling of the material will cause geometrical distortions and may cause low joint quality. 700 mm long U-beam structures of 1 mm thick boron steel simulating structural pillars in body-in-white constructions have been laser welded along the flanges with different welding speeds to investigate distortions and weld quality. The results show that final distortions appear in the range of 0-8 mm. FE simulation methods have also been presented which generally predict the distribution of welding distortions.

  • 19. Gårdstam, Johannes
    et al.
    Melander, Arne
    KTH, Superseded Departments, Production Engineering.
    Self-piercing riveting of stainless steel sheets: simulation and verification2004In: 11th Paderborner Symposium Fügetechnik, LWF Labor fur Werkstoff und Fugetechnik der Universität Paderborn , 2004, p. 135-143Conference paper (Refereed)
  • 20.
    Khodaee, Alireza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. SWEREA KIMAB, Sweden.
    Evaluation of effects of geometrical parameters on density distribution in compaction of PM gears2017In: 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.

  • 21.
    Khodaee, Alireza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Finite Element Analysis on the Friction Effects in the Gear Rolling Process2013In: NEWTECH 2013, 2013Conference paper (Refereed)
    Abstract [en]

    Gear rolling as a manufacturing method for gear wheels has a number of advantages in comparison with traditional gear production methods which makes it an interesting topic for scientific research. The main benefits are reduced material consumption, fast cycle time of the process, improved strength of the product due to the alignment of the microstructure during cold forming and a good surface quality.

    There are several factors which can influence the process quality and accuracy of the geometry in the final state. One of the most important parameters is the friction between the tool and the blank during the forming process. Therefore it is of interest to study the effect of different friction models in finite element simulations to evaluate its effects on final gear wheel shape.

    In this paper the shear friction model is studied. Two friction factors will be studied in this case. Two dimensional FE calculations will be performed with the code DEFORM. The results of the FE simulations and the effect of friction factor on gear flank and tip geometry are presented. One example is presented of the effect on the so called “rabbit ear “at the gear tip.

  • 22.
    Khodaee, Alireza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Finite Element Simulation as a Tool to Evaluate Gear Quality after Gear Rolling2013In: Current State-Of-The-Art On Material Forming: Numerical And Experimental Approaches At Different Length-Scales, Pts 1-3, Trans Tech Publications Inc., 2013, Vol. 554-557, p. 300-306Conference paper (Refereed)
    Abstract [en]

    Gear rolling is a manufacturing technique for gears with many advantages like reducedmaterial consumption, reduced scrap generation, fast cycle times, good surface quality andimproved final properties of the gear wheels compared to conventional production technology basedon machining. In order to make use of all these advantages it is desired to reach the final shape ofthe gear wheel already after rolling. This means that post treatments like grinding should beavoided. This puts high requirements on the shape accuracy after gear rolling.In this paper it was studied if finite element simulation could be used to evaluate the shape accuracyafter gear rolling. The measurement of shape accuracy of gear wheels is specified in standards likeISO1328-1. The allowed deviations from nominal shape are often of the order of 10-30 μm for verygood qualities. So if such evaluation shall be possible from a finite element simulation the accuracymust be of the same order.In order to have sufficient accuracy of the finite element simulation 2D simulations were performedon a spur gear. The FE code DEFORM was utilized. The shape accuracy was evaluated for gearrolling of two cases. One case had gears with the module of 1 mm. The other case involved gearswith a significantly larger module of 4 mm. This was an interesting case since it is known that it ismore difficult to roll the gear with good accuracy in large modules.

  • 23.
    Khodaee, Alireza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Process planning of gear rolling with the finite element method2014In: 15th International Conference on Metal Forming 2014, 2014, Vol. 622-623, p. 986-992Conference paper (Refereed)
    Abstract [en]

    Gear rolling is a new gear manufacturing process which can partly replace traditional gear milling processes. High gear wheels with modules of 4mm up to 6mm are of interest to truck manufacturing. The process is of interest since it involves no material removal and since it has the potential to give good performance of the gear wheels. The process must be adopted for the large plastic deformations which occur for gear rolling with large modules. In this paper special emphasis will be put to loads and torques during the gear rolling process of gear wheels with large modulus. The FE method will be used to model the plastic deformation process to fully form a gear wheel with the gear rolling method. The radial and axial loads and the torques in this process are predicted. The loads of the process are high compared to the situation for small gear wheels so simulation of load level is essential for the design of rolling machines for high gears.

  • 24.
    Khodaee, Alireza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Study of the effect of the reversal cycles in the gear rolling process by using finite element simulations2014In: ESAFORM 2014, 2014, p. 134-141Conference paper (Refereed)
    Abstract [en]

    The manufacturing of machine components with sustainable and innovative methods is an interesting topic for research. Gears are some components which have complexity in both design and production technology. Therefore applying innovative methods on gear manufacturing can be of interest to industry. One of the most promising production methods for gear wheels is Gear Rolling. The gear wheel is formed during a certain rolling process from a cylindrical blank into the final designed shape. The process of gear rolling with rotational gears is progressing by running several rolling cycles with one, or two dies in contact with a work-piece. A specified rotational speed and radial feed speed is applied to the dies in order to form the required geometry on the blank. In this paper, the authors have simulated the process with the finite element code, DEFORM 3D. Especially the effects of reversal cycles on final gear wheel geometry have been evaluated from the simulations. Different settings for the rotation direction of the dies have been used and the effects are evaluated with specific quality criteria.

  • 25.
    Khodaee, Alireza
    et al.
    KTH.
    Melander, Arne
    KTH. Swerea KIMAB AB, S-16440 Kista, Sweden..
    Haglund, Sven
    Swerea KIMAB AB, S-16440 Kista, Sweden..
    The Effects of Blank Geometry on Gear Rolling for Large Gear Modules: Experiments and Finite Element Simulations2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 33344-33352Article in journal (Refereed)
    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.

  • 26.
    Lundberg, Maria
    et al.
    Swerea KIMAB.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Finite element analysis of roll forming of UHSS compared to traditional bending2008In: IDDRG 2008 International Conference / [ed] Nader Asnafi, 2008, p. 331-338Conference paper (Refereed)
  • 27.
    Lundberg, Maria
    et al.
    Swerea KIMAB.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Troive, Lars
    SSAB.
    Maulitz, Sten
    Jensen AS.
    A new test for cracking in roll forming2009In: 1st International Congress on Roll Forming: RollFORM '09, 2009, p. 125-131Conference paper (Refereed)
  • 28.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Arshad, Saad
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Rashid, Amir
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Formability of different aluminium alloys in Single Point Incremental Forming (SPIF) processes2012In: International Deep Drawing Research Group 2012, Mumbai, 2012, 2012Conference paper (Refereed)
  • 29.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Delic, Aldin
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Björkblad, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Juntunen, Pasi
    Samek, Ludovic
    Vadillo, Leire
    Finite element simulation of electro hydraulic forming2010In: International deep drawing research group (IDDRG) conference, Graz, Austria, 2010, p. 749-758Conference paper (Refereed)
  • 30.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Delic, Aldin
    Björkblad, Anders
    Juntunen, Pasi
    Samek, Ludovic
    Vadillo, Leire
    Modelling of electro hydraulic free and die forming of sheet steels2013In: International Journal of Material Forming, ISSN 1960-6206, E-ISSN 1960-6214, Vol. 6, no 2, p. 223-231Article in journal (Refereed)
    Abstract [en]

    Electro hydraulic forming of a range of different sheet steels was studied experimentally and with finite element methods. Four carbon and stainless sheet materials were studied. In this paper we present results on a mild steel (IF210), two high strength steels (DPX800 and TRIP700) and one stainless steel (1.4509). The flow properties of the materials were evaluated at a range of strain rates up to 1000/s. These were typical strain rates in the FE simulations. The flow properties were characterized with the Johnson Cook model. Electro hydraulic forming trails were performed with a chamber of water with a pair of electrodes on one side of the sheet. In one case free forming was performed and in the other case forming was performed into a truncated conical die. Geometrical shapes and strain distributions were evaluated after forming. A finite element model was formulated in ABAQUS explicit. The model takes the chamber filled with water into account and the effect of the electrical discharge is modeled as a pressure wave originating from the location of the electrodes. The sheet is given the properties defined by the Johnson Cook model and stiff tools are used. The forming of the sheet is described including rebound effects at the tools. The model shows satisfactory results in relation to the experimental trials regarding both shape and strains of the pressed sheets.

  • 31.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Gårdstam, Johannes
    Swerea KIMAB.
    Simulation - a useful tool for the development of future applications of self piercing riveting2005In: Automotive circle International Conference on mechanical thermal and hybrid joining processes in automotive engineering / [ed] F Ebert, 2005, p. 377-383Conference paper (Refereed)
  • 32.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Randelius, Mats
    Swerea KIMAB.
    Krantz, Therese
    Swerea KIMAB.
    Simulation of ductile fracture in conventionally cast tool steels2006In: 7th International Tooling conference, 2006, p. 323-329Conference paper (Refereed)
  • 33.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Stenberg, Niclas
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    On the variation of elastic modulus in loading, unloading and reloading2013Conference paper (Refereed)
  • 34.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Stenberg, Niclas
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Lundberg, M
    Björkblad, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Björkstam, D.
    Delic, Aldin
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Sheet metal forming of ultra high strength steels2009In: Proceedings of The International 3’rd Swedish Production Symposium, SPS’09 / [ed] B-G Rosén, Göteborg, 2009, p. 342-347Conference paper (Refereed)
  • 35.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Stenberg, Niclas
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Lundberg, Maria
    Swerea KIMAB.
    Björkblad, Anders
    Swerea KIMAB.
    Delic, aldin
    Swerea KIMAB.
    Björkström, Daniel
    Swerea KIMAB.
    Sheet metal forming of ultra high strength steel2009In: Swedish Production Symposium 2009, 2009, p. 342-347Conference paper (Refereed)
  • 36.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Thoors, Håkan
    Stenberg, Niclas
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    The bending under tension (BUT) machine as a spring back evaluator2011In: IDDRG 2011 Conference: Towards sustainable sheet forming processes, 2011Conference paper (Refereed)
  • 37.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Thoors, Håkan
    Swerea KIMAB.
    Stenberg, Niclas
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Ma, Ning
    RWTH Aachen.
    Spring back evaluation for high and ultra high strength sheet steels with the bending under tension machine2015In: International Journal of Material Forming, ISSN 1960-6206, E-ISSN 1960-6214, Vol. 8, no 1, p. 137-144Article in journal (Refereed)
    Abstract [en]

    The Bending Under Tension (BUT) machine is used for evaluation of spring back in sheet metal forming. A strip is drawn over a rotating cylindrical die with different restraining forces. The strip is allowed to spring back after drawing and the curvature of the strip is measured. The loading sequence is typical to wall sections of pressed components, side wall curl, where the material has been bent, unbent and finally unloaded. The test was performed on four high and ultra high strength steels with tensile strengths in the range from 800 MPa to 1300 MPa. A clear separation of the data for the four steels was demonstrated. It was analysed to what extent the differences in spring back between the different steels was related to the differences in tensile strengths. A finite element simulation model was used to simulate the strip curvature after BUT testing. The material parameters of the model were fitted to monotonic uniaxial and equibiaxial tests and uniaxial cyclic tests. The model could describe the experimental data in a satisfactory way.

  • 38.
    Melander, Arne
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Thoors, Håkan
    SwereaKIMAB.
    Stenberg, Niclas
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Ning, Ma
    RWTH Aachen.
    Spring Back Measurement and Verification of Simulation with the Bending under Tension (BUT) MachineIn: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774Article in journal (Refereed)
  • 39.
    Randelius, Mats
    et al.
    Swerea KIMAB, Sweden.
    Krantz, Therese
    Swerea KIMAB, Sweden.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. Swerea KIMAB, Sweden.
    Experimental Testing and Computer Simulations of Ductile Fracture in Tool Steels2012In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 83, no 1, p. 91-99Article in journal (Refereed)
    Abstract [en]

    Ductility was determined in experimental four-point bending tests of smooth specimens of tool steel. The tool steels had different contents of carbides and carbide sizes and with a hardness of approximately 60HRc. Two of the materials tested were produced powder metallurgically, one was spray formed and one was conventionally uphill ingot cast. Carbide size distribution analysis was performed on planar polished sections of each material. Correlation between carbide microstructure and ductility performance was obtained. The fracture mechanisms were investigated with fractography. A 3D FE-model was used to simulate the four-point bending tests and thereby analyse the matrix flow curve. Also the strain at failure was analysed for each material when simulations were performed based on experimental data. SEM-images of the materials carbide microstructure were used to create 2D FE-models. The models simulated crack initiation and propagation by removing elements in the steel matrix as the plastic strain reached a critical level. With three variants, simulations of crack initiation and propagation at carbides were investigated. That was carbides with no cohesion to matrix, carbides fixed to the matrix and carbides with internal cracks. Comparison of strains at failure for the 2D and the 3D FE-models showed good correlation.

  • 40.
    Randelius, Mats
    et al.
    Corrosion and Metals Research Institute (KIMAB), Stockholm.
    Melander, Arne
    Corrosion and Metals Research Institute (KIMAB), Stockholm.
    How carbides and inclusions influence fatigue strength in tool steels2006In: 7th International Tooling Conference, 2006Conference paper (Other academic)
  • 41.
    Randelius, Mats
    et al.
    Swerea Kimab, Sweden.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. Swerea Kimab, Sweden.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. Swerea Kimab, Sweden.
    Fatigue Strength of Conventionally Cast Tool Steels and its Dependence of Carbide Microstructure2012In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 83, no 1, p. 83-90Article in journal (Refereed)
    Abstract [en]

    The axial fatigue strength at two million cycles was experimentally determined for two conventionally cast tool steels and successfully compared with results from a fatigue limit model. Specimens were tested both in the rolling and transverse direction and showed large differences in fatigue properties due to the segregated carbide microstructure. Rolling direction specimens experienced higher fatigue strength than the transverse direction specimens. This is due to smaller carbides present in the load affected cross section of the rolling direction fatigue test bars compared to the cross section of the transverse direction fatigue test bars. Fractographic analysis of failed specimens showed that large carbides had caused fatigue failure, which was also predicted by the model. Measured size distributions of carbides and inclusions were used as input data in the model. The probability that at least one particle will be present in the material volume having a size larger than the threshold value for crack propagation was calculated.

  • 42.
    Ratanathavorn, Wallop
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    A study of friction stir welded joint between AA5754 and ultra-high strength steel in hot dip galvanized condition2014In: 10th Friction Stir Welding Symposium, Beijing, China, 2014, p. S2B-P5-Conference paper (Refereed)
  • 43.
    Ratanathavorn, Wallop
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. KTH, Centres, XPRES, Excellence in production research. Swerea KIMAB AB, Sweden.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering. KTH, Centres, XPRES, Excellence in production research. Swerea KIMAB AB, Sweden.
    Dissimilar joining between aluminium alloy (AA 6111) and thermoplastics using friction stir welding2015In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936, Vol. 20, no 3, p. 222-228Article in journal (Refereed)
    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.

  • 44.
    Ratanathavorn, Wallop
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Dissimilar joining between alumnium alloy AA6111 and thermoplastics using friction stir weldiing2015In: Science and technology of welding and joining, ISSN 1362-1718, E-ISSN 1743-2936Article in journal (Refereed)
  • 45.
    Ratanathavorn, Wallop
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Joining of hybrid joints between thermoplastics and alumnium alloy by friction stir lap welding: a feasability study2014In: 10th Friction Stir Welding Symposioum, 2014, p. S6B-P4-Conference paper (Refereed)
  • 46.
    Rathanatavorn, Wallop
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology.
    Lindh-Ulmgren, Eva
    Swerea KIMAB.
    Åkermo, Malin
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Burman, Magnus
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. mburman@kth.se.
    Hybrid joining of alumnium to thermoplastics with friction stir welding2012In: Proceedings Swedish production  Symposium 2012, 2012Conference paper (Refereed)
  • 47. Sagström, Elisabeth
    et al.
    Wadman, Boel
    Moshfegh, R.
    Lundberg, Maria
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    The Geometrical Robustness of roll formed profiles in ultra high strength steels2008In: IDDRG 2008 / [ed] Nader Asnafi, 2008, p. 339-347Conference paper (Refereed)
  • 48. Samek, L.
    et al.
    Björkström, Daniel
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Arenholz, A.
    Vadillo, Leire
    Characterisation and modelling of the influence of the strain rate on the mechanical behaviour of high strength steels and stainless steels2009In: IDDRG 2009, 2009, p. 219-230Conference paper (Refereed)
  • 49.
    Stenberg, Niclas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Modelling the circular blanking process including tool wear2008In: IDDRG 2008, Olofström, Sweden / [ed] Nader Asnafi, 2008, p. 777-784Conference paper (Refereed)
  • 50.
    Stenberg, Niclas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Tavakol, Mohammad
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Thoors, Håkan
    Swerea KIMAB.
    Verification of finite element simulation models for spring back with experimental BUTtesting of ultra high strength steels2012Conference paper (Refereed)
12 1 - 50 of 53
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