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  • 1.
    Barlo, Alexander
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Manopulo, Niko
    AutoForm Engineering GmbH, Switzerland .
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Endelt, Benny
    Aalborg University, Denmark.
    Trana, Kristoffer
    Volvo Cars Stamping Engineering, Olofström.
    Investigation of a Bending Corrected Forming Limit Surface for Failure Prediction in Sheet Metals2019Ingår i: Forming Technology Forum, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ensuring process feasibility is a high priority in the automotive industry today. Within theCAE departments concerning the manufacturing of body components, one of the most important areas ofinterest is the accurate prediction of failure in components through Finite Element simulations. This paperinvestigates the possibility of introducing the component curvature as a parameter to improve failureprediction. Bending-under-tension specimens with different radii are used to create a Bending CorrectedForming Limit Surface (BC-FLS), and a test die developed at Volvo Cars, depicting production-like scenariosby exposing an AA6016 aluminium alloy blank to a stretch-bending condition with biaxial pre-stretching, isused to validate the proposed model in the commercial Finite Element code AutoFormTM R8. The findings ofthis paper showed that the proposed BC-FLS approach performed well in the failure prediction of the test diecompared to the already in AutoFormTM R8 implemented max failure approach.

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  • 2.
    Barlo, Alexander
    et al.
    Volvo, SWE.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Endelt, Benny
    Aalborg Universitet, DEN.
    On the Failure Prediction of Dual-Phase Steel and Aluminium Alloys Exposed to Combined Tension and Bending2019Ingår i: IOP Conference Series: Materials Science and Engineering / [ed] VanDenBoogaard, T; Hazrati, J; Langerak, N, Institute of Physics Publishing , 2019, Vol. 651, nr 1, artikel-id 012030Konferensbidrag (Refereegranskat)
    Abstract [en]

    The interest in accurate prediction of failure of sheet metals in the automotive industry has increased significantly over the last two decades. This paper aims to evaluate two failure prediction approaches implemented in the commercial Finite Element code AutoFormplus R7.04; (i) the standard Forming Limit Diagram (FLD), and (ii) the Non-linear Forming Limit Diagram. The evaluation will be testing the two approaches accuracy on predicting failure of both an AA6016 aluminium alloy and a CR440Y780T-DP dual-phase steel alloy specimen exposed to combined tension and bending. Based on the findings of this study, it is concluded that neither of the evaluated approaches is able to accurately predict failure in both cases presented. © Published under licence by IOP Publishing Ltd.

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    On the Failure Prediction of Dual-Phase Steel and Aluminium Alloys
  • 3.
    Barlo, Alexander
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Islam, Md. Shafiqul
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Perez, Ll
    RISE, Sweden.
    Olofsson, E.
    Volvo Cars, Gothenburg, Sweden..
    Al-Fadhli, M.
    Volvo Cars, Olofstrom, Sweden..
    Tuan Pham, Quoc
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Odenberger, E-L
    RISE, Sweden.
    Proposal of a New Tool for Pre-Straining Operations of Sheet Metals and an Initial Investigation of CR4 Mild Steel Formability2023Ingår i: 42ND CONFERENCE OF THE INTERNATIONAL DEEP DRAWING RESEARCH GROUP / [ed] Asnafi, N Lindgren, LE, IOP PUBLISHING LTD , 2023, Vol. 1284, artikel-id 012079Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the increased focus on reducing carbon emissions in the automotive industry, more advanced materials are introduced to reduce the vehicle weight, and more complex component geometries are designed to both satisfy customer demands and to optimize the vehicle aerodynamically. With the increase in component complexity, the strain paths produced during the forming operation of car body components often display a highly non-linear behavior which makes the task of failure prediction during the manufacturing feasibility studies more difficult. Therefore, CAE engineers need better capabilities to predict failure induced by strain path nonlinearity. This study proposes a new tool designed for creating bi-linear strain paths, by performing a pre-strain of a sheet large enough to cut out Nakajima specimens to perform the post-straining in any direction. From five pre-straining tests the tool present a stable pre-straining operation with a uniform strain field in a radius of 100 [mm] from the centre, corresponding to the region of interest of a Nakajima specimen. From the five pre-strained samples, different Nakajima specimens are cut transverse and longitudinal to the rolling direction and a failure prediction approach in an alternative, path independent evaluation space was used to predict the onset of necking with promising results.

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  • 4.
    Barlo, Alexander
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Kesti, V.
    SSAB Europe Oy, Finland..
    Islam, Md. Shafiqul
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Tuan Pham, Quoc
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Determination of Edge Fracture Limit Strain for AHSS in the ISO-16630 Hole Expansion Test2023Ingår i: 42ND CONFERENCE OF THE INTERNATIONAL DEEP DRAWING RESEARCH GROUP / [ed] Asnafi, N Lindgren, LE, IOP PUBLISHING LTD , 2023, Vol. 1284, artikel-id 012027Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the increased demand for application of sustainable materials and lightweight structures, the sheet metal forming industry is forced to push existing materials to the limits. One area where this is particular difficult is when it comes to assessing the formability limit for sheet edges. For decades, the ISO-16630 Hole Expansion Test (HET) has been the industry standard for expressing the edge formability of sheet metals through the Hole Expansion Ratio (HER). However, in recent years, this test has been criticized for its high scatter in results for repeated experiments. This scatter has been suspected to be caused by the operator-reliant post-processing of the test, or variations in the cutting conditions for the different test specimens. This study investigates the impact of shifting the evaluation point of the test from the through-thickness crack to the onset of surface failure on the reported scatter, as well as performs inverse modeling of the Hole Expansion Test to obtain an edge limit strain value.

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  • 5.
    Barlo, Alexander
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Manopulo, Niko
    AutoForm Development GmbH, CHE.
    Islam, Md. Shafiqul
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Failure Prediction of Automotive Components Utilizing a Path Independent Forming Limit Criterion2022Ingår i: Key Engineering Materials / [ed] Vincze G., Barlat F., Trans Tech Publications Inc., 2022, s. 906-916Konferensbidrag (Refereegranskat)
    Abstract [en]

    An area in the automotive industry that receives a lot of attention today is the introduction of lighter and more advanced material grades in order to reduce carbon emissions, both during production and through reduced fuel consumption. As the complexity of the introduced materials and component geometries increases, so does the need for more complex failure prediction approaches. A proposed path-independent failure criterion, based on a transformation of the limit curve into an alternative evaluation space, is investigated. Initially, the yield criterion used for this transformation of the limit curve was investigated. Here it was determined that the criterion for the transformation could not be decoupled from the material model used for the simulation. Subsequently, the approach using the transformed limit curve was tested on an industrial case from Volvo Cars, but a successful failure prediction was not obtained. © 2022 The Author(s). Published by Trans Tech Publications Ltd, Switzerland.

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  • 6.
    Barlo, Alexander
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Perez, L.
    RISE IVF AB.
    Islam, Md. Shafiqul
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    A Study of the Boundary Conditions in the ISO-16630 Hole Expansion Test2022Ingår i: INTERNATIONAL DEEP-DRAWING RESEARCH GROUP CONFERENCE (IDDRG 2022) / [ed] Thuillier, S Grolleau, V Laurent, H, Institute of Physics (IOP), 2022, Vol. 1238Konferensbidrag (Refereegranskat)
    Abstract [en]

    As new and more advanced sheet metal materials are introduced to the market, more accurate techniques for determination of failure limits are needed. One area that needs attention is edge formability, where the ISO-16630 standardized Hole Expansion Test currently is used to express this through the Hole Expansion Ratio. Over the years, this standard has been criticized for producing a large scatter in repeated tests. This paper investigates a new setup for the Hole Expansion Test which introduces draw beads into the setup to ensure sufficient restraining of the specimen during the test in an effort to reduced the scatter. In total 62 tests of a DP800 steel alloy were executed, but a large scatter in the results were still seen. It was therefore concluded that a lack of restraining force in the Hole Expansion Test was not the primary cause of the reported scatter seen in other tests.

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  • 7.
    Chezan, A. R.
    et al.
    Tata Steel R&D, Netherlands..
    Atzema, E. H.
    Tata Steel R&D, Netherlands.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Material variability effects on automotive part production process2023Ingår i: 42ND CONFERENCE OF THE INTERNATIONAL DEEP DRAWING RESEARCH GROUP / [ed] Asnafi, N Lindgren, LE, IOP PUBLISHING LTD , 2023, Vol. 1284, artikel-id 012037Konferensbidrag (Refereegranskat)
    Abstract [en]

    The current efforts to reduce the carbon footprint throughout the chain in the automotive industry by increased use of recycled materials poses new challenges for materials production and their use. The increase of steel scrap fraction in the current primary steel making processes, used for producing steel sheet metal for automotive components, possibly affects the material properties variability beyond the limits observed in the materials produced today despite mitigating actions in steel production. In this paper material variability increase was modelled by selecting deterministic values outside the range of the material grade used to design and manufacture an automotive part. The values were selected from an experimental data set representing the cold rolled mild steels material class range. The effects were studied numerically on a reverse engineered model of an existing automotive part production process. It was found that the manufacturing feasibility in this particular case is mainly affected by the weighted average plastic strain ratio and less by the degree of planar anisotropy.

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  • 8.
    Chezan, A. R.
    et al.
    Tata Steel Europe Limited, GBR.
    Khandeparkar, Tushar V.
    Tata Steel Europe Limited, GBR.
    Ten Horn, Carel H. L. J.
    Tata Steel Europe Limited, GBR.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Accurate sheet metal forming modeling for cost effective automotive part production2019Ingår i: IOP Conference Series: Materials Science and Engineering / [ed] VanDenBoogaard, T; Hazrati, J; Langerak, N, Institute of Physics Publishing , 2019, Vol. 651, nr 1, artikel-id 012007Konferensbidrag (Refereegranskat)
    Abstract [en]

    Recent implementations of accurate material and tribology models in finite element codes for sheet metal forming process development have the potential to reduce development time and the associated development costs significantly. Adoption of new models requires validated material parameters and assessments of the overall accuracy. The paper presents a study aimed at accuracy estimation by comparing strain measurements and finite element simulation results for a laboratory flat bottom hole expansion test and an industrial automotive component produced at Volvo Cars. The use of the tensile test based Tata Steel Vegter yield locus model results in accurate prediction of dimensions and plastic deformation distribution in sheet metal forming applications. © Published under licence by IOP Publishing Ltd.

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    Accurate sheet metal forming modeling for cost effective automotive partproduction
  • 9.
    Chezan, Tony
    et al.
    Tata Steel, NLD.
    Khandeparkar, Tushar
    Tata Steel, NLD.
    Van Beeck, Jeroehn
    Tata Steel, NLD.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Strategies for increasing the accuracy of sheet metal forming finite element models2018Ingår i: Journal of Physics: Conference Series, Institute of Physics Publishing , 2018, nr 1Konferensbidrag (Refereegranskat)
    Abstract [en]

    Accurate modelling of sheet metal forming can contribute significantly to reduction of lead time and development costs in manufacturing industries. The current way to improve the finite element model accuracy is to combine advanced constitutive material models and advanced tribological models. For model validation purposes the geometry of the forming tools needs to be updated and the most relevant parameters of the forming press needs to be incorporated. The addition of a simple and easier to control model test can offer additional information on difficult to characterize parameters of the industrial process. The industrial validation case presented in this paper demonstrates that the Tata Steel constitutive material model has similar prediction capability as the state of the art material model used at Volvo Cars for regular process development for automotive parts production. In both industrial and model tests the tribological system appears to affect significantly the overall model accuracy. The model tests suggests that further work is needed in order to improve the tribological model description at high contact pressure and high strain levels. © 2018 Institute of Physics Publishing. All rights reserved.

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  • 10.
    Domhof, A. T. M.
    et al.
    TriboForm Engineering, Netherlands.
    Waanders, D.
    TriboForm Engineering, Netherlands.
    Hol, J.
    TriboForm Engineering, Netherlands.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Friction and lubrication modelling in sheet metal forming: Influence of local tool roughness on product quality2023Ingår i: 42ND CONFERENCE OF THE INTERNATIONAL DEEP DRAWING RESEARCH GROUP / [ed] Asnafi, N Lindgren, LE, IOP PUBLISHING LTD , 2023, Vol. 1284, artikel-id 012087Konferensbidrag (Refereegranskat)
    Abstract [en]

    To improve the accuracy of forming simulations, advanced friction models are increasingly used in the industry. These models account for the physical properties of the sheet, tool and lubrication and describe the tribological conditions during the forming operation. One of the main influencing factors on the tribology system, and therefore the friction coefficient, is the surface roughness of the tools. Until now, it is often assumed all tools have the same uniform surface roughness. In reality however, the tool might have different surface conditions dependent on the type and location of the tool. That is, the blank holder might be differently polished than the punch, and sharp radii might have a different tool roughness compared to flat areas. This paper investigates a significant number of tool measurements from different tool sets from Volvo Cars, and quantifies the effect of local surface conditions on product quality.

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  • 11.
    Manopulo, N.
    et al.
    AutoForm Dev GmbH, CHE.
    Chezan, A. R.
    Tata Steel, NLD.
    Atzema, E.
    Tata Steel, NLD.
    Anfruns, I. Picas
    Tata Steel, NLD.
    Carleer, B.
    AutoForm Engn Deutschland GmbH, DEU.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    On the mechanics of edge cracking and the reliable determination of edge formability limits2021Ingår i: INTERNATIONAL DEEP-DRAWING RESEARCH GROUP CONFERENCE (IDDRG 2021) / [ed] Liewald, M, Karadogan, C, IOP PUBLISHING LTD , 2021, Vol. 1157, artikel-id 012055Konferensbidrag (Refereegranskat)
    Abstract [en]

    Blanked edge surfaces are rough and hardened. They therefore lead to inhomogeneous deformation on the edge, which can trigger localization within the shear affected zone (up to few mm from the edge). The size and extent of these phenomena are primarily a function of the shearing process and are only marginally coupled to the global/homogeneous deformation behavior of the blank A direct numerical simulation of such local deformation effects would require a prohibitively high resolution to capture the microgeometry of the edge and thus remains unfeasible in the current industrial practice. A predictive model can therefore only be achieved by determining limit strains on the edge, which are compatible with the homogeneous numerical framework used. The present contribution aims discussing the basic mechanics of edge cracking based on tensile tests with edges blanked with different die clearances. The local and global strain evolutions in the vicinity of the edge are analysed and a new evaluation procedure is proposed for the reliable determination of limit strains. The application of this method in industrial context is also discussed.

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  • 12.
    Ottosson, P.
    et al.
    RISE AB, Div Mat & Prod, Sweden.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. Volvo Cars, Sweden.
    Wiklund, D.
    RISE AB, Div Mat & Prod, Sweden.
    Skare, T.
    RISE AB, Div Mat & Prod, Vallaregatan 30, SE-29338 Olofstrom, Sweden..
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Substitutive models of press deflections for efficient numerical die cambering2023Ingår i: 42ND CONFERENCE OF THE INTERNATIONAL DEEP DRAWING RESEARCH GROUP / [ed] Asnafi, N Lindgren, LE, IOP PUBLISHING LTD , 2023, Vol. 1284, artikel-id 012060Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cost and time for stamping die tryouts are significant within the car industry. A major contributing factor is that elastic deflections of stamping dies and presses are usually not considered during the virtual die design and forming simulation phase. Active surfaces of stamping dies are only cambered based on previous experiences of tool types and stamping presses. However, almost all stamping dies and presses are unique, and available experiences are not valid for new sheet materials. This leads to component deviations and often several loops of tool adjustments are needed. Previously partners within the SMART Advanced Manufacturing research project CAMBER have developed advanced deflection measuring devices to quantify the elastic deformations of stamping presses. Using these measurements, cambering methodologies can be utilized in sheet metal forming simulations. In this paper numerical substitutive stamping press models are described which are capable of compensating for measured stamping press dynamics. The result show that a numerical compensated tool can improve the contact by over 80% compared to the corresponding contact without compensation.

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  • 13.
    Pilthammar, Johan
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Allesson, Sara
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. (student).
    Lind, Markus
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. (student).
    Schill, Mikael
    Dynamore Nordic.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sjöblom, Viktor
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. (student).
    A Complete and Rapid Simulation Method for Virtual Try-out of Stamping Dies Considering Elastic DeformationsManuskript (preprint) (Övrigt vetenskapligt)
  • 14.
    Pilthammar, Johan
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. Volvo Cars, SWE.
    Schill, Mikael
    Dynamore Nordic.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. Volvo Cars, SWE.
    Sjöblom, Viktor
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. (Student).
    Lind, Markus
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. (Student).
    Simulation of Sheet Metal Forming using Elastic Stamping Dies2019Ingår i: Proc. of the 12th European LS-DYNA Conference 2019, 2019, 2019Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Simulation of sheet metal forming is one of the major applications of LS-DYNA. Today, a majority of the forming industry is using Finite Element models to design the stamping dies in order to prevent excessive thinning, wrinkling and producing parts within tolerance by compensating for springback deformation. All these simulations are made using the assumption of rigid forming surfaces. Depending on the type of press, tool design and sheet metal part, this assumption could prove to be incorrect which yields a forming result that depends on the elastic deformation of the stamping die and in some cases the entire stamping press. Such deformations are usually compensated during die try-out by manual rework which is costly and time consuming.

    This paper presents the result of a study performed at Volvo Cars press shop in Olofström, Sweden, aiming at determining computational methods to introduce elastic stamping dies in the sheet metal forming simulations in order to minimize manual rework by performing a virtual tryout of the stamping die. The methodology to model the stamping die and the forming surfaces in LS-DYNA are presented and a simulation model is gradually improved from using nominal rigid CAD surfaces through scanned tool surfaces and finishing with an elastic model of the stamping die assembly. The part used in the study is the side door inner for Volvo XC90 and comparisons are continuously made between simulations results and measurements on parts from running production.

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    Simulation of Sheet Metal Forming using Elastic Stamping Dies
  • 15. Pilthammar, Johan
    et al.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Hansson, Mårten
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pálsson, Einar
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Rutgersson, Wilhelm
    Cascade Control AB, SWE.
    Characterizing the Elastic Behaviour of a Press Table throughTopology Optimization2017Ingår i: Journal of Physics: Conference Series / [ed] Volk W., Institute of Physics Publishing (IOPP), 2017, Vol. 896, artikel-id 012101Konferensbidrag (Refereegranskat)
    Abstract [en]

    Sheet metal forming in the car industry is a highly competitive area. The use ofdigital techniques and numerical methods are therefore of high interest for reduced costs andlead times. One method for reducing the try-out phase is virtual rework of die surfaces. Thevirtual rework is based on Finite Element (FE) simulations and can reduce and support manualrework. The elastic behaviour of dies and presses must be represented in a reliable way in FEmodelsto be able to perform virtual rework. CAD-models exists for nearly all dies today, butnot for press lines. A full geometrical representation of presses will also yield very large FEmodels.This paper will discuss and demonstrate a strategy for measuring and characterizing apress table for inclusion in FE-models. The measurements of the elastic press deformations iscarried out with force transducers and an ARAMIS 3D optical measurement system. The presstable is then inverse modelled by topology optimization using the recorded results as boundaryconditions. Finally, the press table is coupled with a FE-model of a die to demonstrate itsinfluence on the deformations. This indicates the importance of having a reliable representationof the press deformations during virtual rework.

  • 16.
    Pilthammar, Johan
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Islam, Md. Shafiqul
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Schill, M.
    Dynamore Nord, Sweden.
    Sjoblom, S.
    Blekinge Tekniska Högskola. student.
    Sjoblom, V.
    Blekinge Tekniska Högskola. student.
    Lind, M.
    Blekinge Tekniska Högskola. student.
    An overview of Methods for Simulating Sheet Metal Forming with Elastic Dies2023Ingår i: 42ND CONFERENCE OF THE INTERNATIONAL DEEP DRAWING RESEARCH GROUP / [ed] Asnafi, N Lindgren, LE, IOP PUBLISHING LTD , 2023, Vol. 1284, artikel-id 012054Konferensbidrag (Refereegranskat)
    Abstract [en]

    Sheet metal forming (SMF) simulations are traditionally carried out with rigid active forming surfaces. This means that the elasticity and dynamics of presses and die structures are ignored. The only geometries of the tools included in the simulations are the active forming surfaces. One reason for this simplification is the large amount of computational power that is required to solve finite element (FE) models that incorporates elastic stamping dies. Another reason is the lack of die CAD models before the later stages of stamping projects. Research during the last couple of decades indicated potential large benefits when including elastic dies in SMF simulations. For example, for simulating die try-out or for Digital Twins of presses and dies. Even though the need and potential benefits of elastic dies in simulations are well known it is not yet implemented on a wide scale. The main obstacles have been lacking data on presses and dies, long simulation times, and no standardized implementation in SMF software. This paper presents an overview of existing methods for SMF simulations with elastic dies and discuss their respective benefits and drawbacks. The survey of methods shows that simulation models with elastic tools will be needed for detailed analyses of forming operations and also for purposes like digital twins. On the other hand, simplified and robust models can be developed for non-FEA users to carry out simple one-step compensation of tool surfaces for virtual spotting purposes. The most promising and versatile method from the literature is selected, modified, and demonstrated for industrial sized dies.

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  • 17.
    Pilthammar, Johan
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Islam, Md. Shafiqul
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Schill, M.
    Dynamore Nord, Sweden..
    Sjoblom, S.
    Blekinge Tekniska Högskola. student.
    Sjoblom, V.
    Blekinge Tekniska Högskola. student.
    Lind, M.
    Blekinge Tekniska Högskola. student.
    Three Industrial Cases of Sheet Metal Forming Simulations with Elastic Dies2023Ingår i: 42ND CONFERENCE OF THE INTERNATIONAL DEEP DRAWING RESEARCH GROUP / [ed] Asnafi, N Lindgren, LE, IOP PUBLISHING LTD , 2023, Vol. 1284, artikel-id 012055Konferensbidrag (Refereegranskat)
    Abstract [en]

    Previous research and experience points to many advantages if sheet metal forming is simulated with elastic dies. Some areas that are enabled by simulations with elastic dies are virtual spotting, improved digital twins, and improved production support. A promising method was selected from the literature, and after important modifications it is deemed to be fast and robust for simulating industrial sized dies. The method consists of meshing die solids with a coarse mesh to represent the structural behaviour of the die. The forming surfaces are then represented by a fine shell mesh connected to the solid mesh by tied contacts with an offset. With additional modifications to reduce solver time this yields a robust and flexible way of modelling sheet metal forming with elastic dies. There is an increase in preprocessing and simulation time compared to using rigid tools, but industrial dies can now be modeled within an hour and solved within a working day. It is also easy to update the model by replacing separate parts such as die solids or forming surfaces. One of the main criteria in favor of the selected approach is the realistic modeling of blankholder and cushion systems. In this paper simulations of three industrial cases are demonstrated: one case of virtual die spotting and two cases of production support. The three cases demonstrate the importance and potential of using elastic dies during virtual die tryout, production support, and for cases like digital twins and production control.

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  • 18.
    Pilthammar, Johan
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Kao-Walter, Sharon
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Introduction of elastic die deformations in sheet metal forming simulations2018Ingår i: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 151, nr S1, s. 76-90Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Simulations of sheet metal forming (SMF) with finite element models (FE-models) for stamped parts in the car industry are useful for detecting and solving forming problems. However, there are several issues that are challenging to analyze. Virtual tryout and analyzes of stamping dies in running production are two important cases where many of these challenging issues are present. Elastic deformations of dies and press lines and a physically based friction model is often missing when these types of cases are analyzed. To address this, this research aims to develop a method wherein the results of two separate FE-models are combined to enable SMF simulations with the inclusion of elastic tool and press deformations. The two FE-models are one SMF model with two-dimensional (2D) rigid tool surfaces and one structural model of the die and press. The structural model can predict surface shapes and pressure distributions for a loaded stamping die. It can also visualize relatively large and unexpected deformations of the die structure. The recommended method of transferring the deformations from the structural model to the 2D surfaces is through an FE technique called submodeling. The subsequent SMF simulations show that the method for calculating and using the deformed surfaces together with the TriboForm friction model yields a result that matches measured draw-in and strains. It is verified that the ability to virtually deform a die and include the resulting geometry in forming simulations is of high importance. It can be used for the virtual tryout and optimization of new dies or analyses of existing dies in running production. It is suggested that future research focus on a more efficient and automated workflow. More experimental data and simulations are also needed to verify the assumptions made for the simulation models. This will enable the method to be adopted in a reliable way for standard SMF simulations. © 2017.

  • 19.
    Pilthammar, Johan
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Skare, T.
    RISE IVF AB, Div Mat & Prod, SWE.
    Galdos, L.
    Mondragon Unibertsitatea ESP.
    Frojdh, K.
    Proximion AB, SWE.
    Ottosson, P.
    RISE IVF AB, Div Mat & Prod, SWE.
    Wiklund, D.
    RISE IVF AB, Div Mat & Prod, SWE.
    Carlholmer, J.
    RISE IVF AB, Div Mat & Prod, SWE.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Ohlsson, M.
    RISE IVF AB, Div Mat & Prod, SWE.
    Saenz de Argandona, E.
    Mondragon Unibertsitatea, ESP.
    Abbasi, F.
    Mondragon Unibertsitatea, ESP.
    Sarasua, O.
    Fagor Arrasate S Coop, ESP.
    Garro, A.
    Koniker S Coop, ESP.
    Rutgersson, W.
    Cascade Control AB, SWE.
    New press deflection measuring methods for the creation of substitutive models for efficient die cambering2021Ingår i: INTERNATIONAL DEEP-DRAWING RESEARCH GROUP CONFERENCE (IDDRG 2021) / [ed] Liewald, M, Karadogan, C, IOP PUBLISHING LTD , 2021, Vol. 1157, artikel-id 012076Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cost and time for die tryout are significant within the car industry, and elastic deflections of dies and presses are most commonly not considered during the virtual die design and forming simulation phase. Because of this, active surfaces of stamping dies are only cambered based on previous experiences of tool types and presses. However, almost all stamping dies and presses are unique, and available experiences are not valid for new materials. Partners within the Eureka SMART Advanced Manufacturing research project CAMBER have developed advanced deflection measuring devices to quantify the elastic deformations of presses. Using these measurements, cambering methodologies can be utilized in sheet metal forming simulations. Important breakthroughs in recent years enabling the cambering methodology consists of efficient simulation strategies for full scale simulations with elastic dies and optimization techniques for creating substitutive press structures based on measurements. Furthermore, modem press deflection measurement methods are beneficial in applications such as Industry 4.0, predictive maintenance, product quality control, etc. through a more advanced understanding and live monitoring of the press system.

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  • 20.
    Pilthammar, Johan
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Wall, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Framework for Simulation-Driven Design of Stamping Dies Considering Elastic Die and Press Deformations2017Ingår i: PROCEEDINGS OF THE 20TH INTERNATIONAL ESAFORM CONFERENCE ON MATERIAL FORMING (ESAFORM 2017) / [ed] Brabazon D.,Ul Ahad I.,Naher S., American Institute of Physics (AIP), 2017, Vol. 1896, artikel-id 010001Konferensbidrag (Refereegranskat)
    Abstract [en]

    Sheet metal forming (SMF) simulations are used extensively throughout the development phase of industrialstamping dies. In these SMF simulations, the die and press are normally considered as rigid. Previous research has howevershown that elastic deformation in these parts has a significant negative impact on process performance. This paperdemonstrates methods for counteracting these negative effects, with a high potential for improved production support anda reduced lead time through a shorter try-out process. A structural finite element model (FE-model) of a simplified die isstudied. To account for elastic deformation, the blankholder surfaces are first virtually reworked by adjusting the nodalpositions on the die surfaces attaining a pressure distribution in accordance to the design phase SMF simulations with rigidsurfaces. The elastic FE-model with reworked surfaces then represents a stamping die in running production. The die isnow assumed to be exposed to changed process conditions giving an undesired blankholder pressure distribution. Thechanged process conditions could for example be due to a change of press line. An optimization routine is applied tocompensate the negative effects of the new process conditions. The optimization routine uses the contact forces acting onthe shims of the spacer blocks and cushion pins as optimization variables. A flexible simulation environment usingMATLAB and ABAQUS is used. ABAQUS is executed from MATLAB and the results are automatically read back intoMATLAB. The suggested optimization procedure reaches a pressure distribution very similar to the initial distributionassumed to be the optimum, and thereby verifying the method. Further research is needed for a method to transform thecalculated forces in the optimization routine back to shims thicknesses. Furthermore, the optimization time is relativelylong and needs to be reduced in the future for the method to reach its full potential.

  • 21.
    Sigvant, Mats
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Falk, Johannes
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Experiments and FE-simulations of stretch flanging of DP-steels with different shear cut edge quality2017Ingår i: Journal of Physics: Conference Series / [ed] Volk W., Institute of Physics Publishing , 2017, Vol. 896, nr 1, artikel-id 012101Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dual-Phase (DP) steels are today used in the automotive industry due to its large strength to weight ratio. However, the high strength of DP-steel does have a negative impact on the general formability in sheet metal forming. Unfavourable process conditions in the press shop will, on top of this, reduce the formability of DP-steels even more. This paper addresses the problem of edge fracture in stretch flanges in sheet metal parts made of DP-steel. The experimental part involves tests of ten different DP590 and DP780 steel grades with three different shear cut qualities. The influence on the fracture strain of the sample orientation of the shear cut are also studied by facing the burr away or towards the punch and testing samples with the cut edge parallel with the rolling direction and the transverse direction. The strains are measured with an ARAMIS system in each test, together with punch displacement and punch force. All tests are then simulated with AutoFormplus R7 and the results from these simulations are compared with the experimental results in order to find the appropriate failure strain for each combination of supplier, coating, thickness and shear cut quality. © Published under licence by IOP Publishing Ltd.

  • 22.
    Sigvant, Mats
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Hol, J.
    TriboForm Engineering, NLD.
    Wiebenga, J. H.
    TriboForm Engineering, NLD.
    Chezan, T.
    Tata Steel, NLD.
    Carleer, B.
    AutoForm Engineering, DEU.
    Van Den Boogaard, A. H.
    University of Twente, NLD.
    Friction in Sheet Metal Forming Simulations: Modelling of New Sheet Metal Coatings and Lubricants2018Ingår i: IOP Conference Series: Materials Science and Engineering, Institute of Physics Publishing , 2018, Vol. 418, nr 1, artikel-id 012093Konferensbidrag (Refereegranskat)
    Abstract [en]

    The quality of sheet metal formed parts is strongly dependent on the tribology and friction conditions that are acting in the actual forming process. These friction conditions are then dependent on the tribology system, i.e. the applied sheet material, coating and tooling material, the lubrication and process conditions. Although friction is of key importance, it is currently not considered in detail in sheet metal forming simulations. The current industrial standard is to use a constant (Coulomb) coefficient of friction, which limits the overall simulation accuracy. Since a few years back there is an ongoing collaboration on friction modelling between Volvo Cars, Tata Steel, TriboForm Engineering, AutoForm Engineering and the University of Twente. In previous papers by the authors, results from lab scale studies and studies of a door-inner part in Volvo Cars production have been presented. This paper focuses on the tribology conditions during early tryout of dies for new car models with an emphasis on the effect of the usage of new steel material coatings and lubricants on forming results. The motivation for the study is that the majority of the forming simulations at Volvo Cars are performed to secure the die tryout, i.e. solve as many problems as possible in forming simulations before the final design of the die and milling of the casting. In the current study, three closure parts for the new Volvo V60 model have been analysed with both Coulomb and TriboForm friction models. The simulation results from the different friction models are compared using thickness measurements of real parts, and 3D geometry scanning data of the parts. Results show the improved prediction accuracy of forming simulations when using the TriboForm friction model, demonstrating the ability to account for the effect of new sheet metal coatings and lubricants in sheet metal forming simulations. © Published under licence by IOP Publishing Ltd.

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  • 23.
    Sigvant, Mats
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Hol, J.
    TriboForm Engineering, NLD.
    Wiebenga, J. H.
    TriboForm Engineering, NLD.
    Chezan, Toni
    Tata Steel, NLD.
    Carleer, Bart
    AutoForm Engineering Deutschland GmbH, DEU.
    Van Den Boogaard, A. H.
    University of Twente, NLD.
    Friction in Sheet Metal Forming: Forming Simulations of Dies in Try-Out2018Ingår i: Journal of Physics: Conference Series, Institute of Physics Publishing , 2018, nr 1Konferensbidrag (Refereegranskat)
    Abstract [en]

    The quality of sheet metal formed parts is strongly dependent on the tribology and friction conditions that are acting in the actual forming process. This paper focuses on the tribology conditions during early try-out of dies for new car models. The motivation for the study is that the majority of the forming simulations at Volvo Cars are performed to secure the die try-out, i.e. solve as many problems as possible in forming simulations before the final design of the die and milling of the casting. In the current study, three closure parts for the new Volvo V60 model have been analysed with both Coulomb and TriboForm friction models. The simulation results from the different friction models are compared using thickness measurements of real parts, and 3D geometry scanning data of the parts. Results show the improved prediction capability of forming simulations when using the TriboForm friction model, demonstrating the ability to accurately describe try-out conditions in sheet metal forming simulations. © 2018 Institute of Physics Publishing. All rights reserved.

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  • 24.
    Sigvant, Mats
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Hol, Jeroen
    TriboForm Engineering, NLD.
    Wiebenga, J. H.
    TriboForm Engineering, NLD.
    Chezan, T.
    Tata Steel, NLD.
    Carleer, Bart
    AutoForm Engineering, DEU.
    Van Den Boogaard, A. H.
    University of Twente, NLD.
    Friction and lubrication modeling in sheet metal forming simulations of a Volvo XC90 inner door2016Ingår i: IOP Conference Series: Materials Science and Engineering, 2016, Vol. 159, nr 1, artikel-id 012021Konferensbidrag (Refereegranskat)
    Abstract [en]

    The quality of sheet metal formed parts is strongly dependent on the tribology, friction and lubrication conditions that are acting in the actual production process. Although friction is of key importance, it is currently not considered in detail in stamping simulations. This paper presents a selection of results considering friction and lubrication modeling in sheet metal forming simulations of the Volvo XC90 right rear door inner. For this purpose, the TriboForm software is used in combination with the AutoForm software. Validation of the simulation results is performed using door inner parts taken from the press line in a full-scale production run. The results demonstrate the improved prediction accuracy of stamping simulations by accounting for accurate friction and lubrication conditions, and the strong influence of friction conditions on both the part quality and the overall production stability. © Published under licence by IOP Publishing Ltd.

  • 25.
    Sigvant, Mats
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Hol, Johan
    TriboForm Engineering, NLD.
    Wiebenga, J. H.
    TriboForm Engineering, NLD.
    Chezan, Toni
    Tata Steel Europe Limited, GBR.
    Carleer, Bart
    AutoForm Engineering, DEU.
    van den Boogaard, Ton
    University of Twente, NLD.
    Friction in sheet metal forming: Influence of surface roughness and strain rate on sheet metal forming simulation results2019Ingår i: Procedia Manufacturing / [ed] Duflou, JR; Carette, Y; Fratini, L; Micari, F; Merklein, M; Hagenah, H, Elsevier B.V. , 2019, Vol. 29, s. 512-519Konferensbidrag (Refereegranskat)
    Abstract [en]

    The quality of sheet metal formed parts is strongly dependent on the tribology and friction conditions that are acting in the actual forming process. These friction conditions are then dependent on the tribology system, i.e. the applied sheet material, coating and tooling material, the lubrication and process conditions. Although friction is of key importance, it is currently not considered in detail in sheet metal forming simulations. The current industrial standard is to use a constant (Coulomb) coefficient of friction, which limits the overall simulation accuracy. Since a few years, back there is an ongoing collaboration on friction modelling between Volvo Cars, Tata Steel, TriboForm Engineering, AutoForm Engineering and the University of Twente. In previous papers by the authors, results from lab scale studies and studies of body parts at Volvo Cars, both parts in early tryout for new car models as well as parts in production have been presented. However, the introduction of a new friction model in the sheet metal forming simulations forces the user to gain knowledge about accurate values for new input parameters and question current modeling assumptions. This paper presents results from studies on the influence on the sheet metal forming simulation results from stamping die surface roughness and introduction of strain rate sensitivity in the sheet material model. The study will use a FE-model of a part presented in previous papers. © 2019 The Authors. Published by Elsevier B.V.

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    Friction in sheet metal forming
  • 26.
    Sigvant, Mats
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Tatipala, Sravan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Andreasson, Eskil
    Tetra Pak Packaging Solutions, SWE.
    SMART STAMPING: IMPROVED QUALITY IN STAMPING BY MODEL DRIVEN CONTROL2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Sheet Metal Forming is a very complex manufacturing process with a number of non-linearities, e.g. large deformations, localisation, elastic-plastic materials, pressure and velocity dependant friction conditions and structural deficiencies in the die and press, present and interacting simultaneously. This leads to disturbances in running production that results in production waste, e.g. down time for the press line and cost for rework and scrapping of parts. These production problems are also hard to understandand solve based on experience and analytical models due to the presence of several non-linearities. An alternative is to try to solve these problems proactively before they occur. This could be done with model based control by creating a digital twin of the die-set and the press line. Therefore, a virtual production process is developed to be able to use as knowledge building and as engineering tool during development, manufacturing, issue resolution and optimization. In this paper presents the authors ideas and plans for research and other activities within the area of model based control of sheet metal forming.

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  • 27.
    Tatipala, Sravan
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Pilthammar, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. Volvo Cars.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. Volvo Cars.
    Wall, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Johansson, Christian
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Introductory study of sheet metal forming simulations to evaluate process robustness2018Ingår i: IOP Conference Series: Materials Science and Engineering, Institute of Physics Publishing (IOPP), 2018, Vol. 418, artikel-id 012111Konferensbidrag (Refereegranskat)
    Abstract [en]

    The ability to control quality of a part is gaining increased importance with desires to achieve zero-defect manufacturing. Two significant factors affecting process robustness in production of deep drawn automotive parts are variations in material properties of the blanks and the tribology conditions of the process. It is imperative to understand how these factors influence the forming process in order to control the quality of a formed part. This paper presents a preliminary investigation on the front door inner of a Volvo XC90 using a simulation-based approach. The simulations investigate how variation of material and lubrication properties affect the numerical predictions of part quality. To create a realistic lubrication profile in simulations, data of pre-lube lubrication amount, which is measured from the blanking line, is used. Friction models with localized friction conditions are created using TriboForm and is incorporated into the simulations. Finally, the Autoform-Sigmaplus software module is used to create and vary parameters related to material and lubrication properties within a user defined range. On comparing and analysing the numerical investigation results, it is observed that a correlation between the lubrication profile and the predicted part quality exists. However, variation in material properties seems to have a low influence on the predicted part quality. The paper concludes by discussing the relevance of such investigations for improved part quality and proposing suggestions for future work.

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  • 28.
    Tatipala, Sravan
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Wall, Johan
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Larsson, Tobias
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Johansson, Christian
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik. Volvo Cars.
    Towards Improving Process Control in Sheet Metal Forming: A Hybrid Data-and Model-Based Approach2020Ingår i: Proceedings of the Swedish Production Symposium / [ed] Kristina Säfsten, Fredrik Elgh, IOS Press, 2020, Vol. 13, s. 367-377Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ability to predict and control involved parameters and hence the outcome of sheet metal forming processes demand holistic knowledge of the product/-process parameter influences and their contribution in shaping the output product quality. Recent improvements in the ability to harvest inline production data and the capability to understand complex process behaviour through computer simulations opens up the possibility for new monitoring and control approaches forimproving production process performance and output product quality. Current work presents a framework for monitoring and control of sheet metal forming processes which incorporates a hybrid data-and-model-based approach. An initial attempt to evaluate the proposed frameworks’ ability to support output product quality and process performance enhancements is made by implementing the proposed approach via an in-house built wire-bending machine prototype. Initial experiments conducted using the built prototype indicate that the proposed framework has the potential to support such enhancements and further work is needed to validate the overall framework.

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    fullpaper_Tatipala et.al.
  • 29.
    Tuan Pham, Quoc
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Islam, Md. Shafiqul
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Barlo, Alexander
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    An evaluation method for experimental necking detection of automotive sheet metals2023Ingår i: 42ND CONFERENCE OF THE INTERNATIONAL DEEP DRAWING RESEARCH GROUP / [ed] Asnafi, N Lindgren, LE, IOP PUBLISHING LTD , 2023, Vol. 1284, artikel-id 012020Konferensbidrag (Refereegranskat)
    Abstract [en]

    In sheet metal stamping, the occurrence of strain localization in a deformed sheet is considered a failure. As so, sheet metal's formability is conventionally evaluated using the Forming Limit Diagram (FLD), which separates the principal strain space into safety and unsafety regions by a Forming Limit Curve (FLC). This study presents an evaluation method for detecting strain localization based on Digital Image Correlation (DIC) during the experiment. The commercial DIC software ARAMIS is adopted to monitor the strain-field distribution on the deformed specimen's surface. A detailed analysis of the proposed method is presented considering Nakajima tests conducted for two automotive sheet metals: AA6016 and DP800. The identified FLC based on the proposed method is compared with that of well-established methods such as ISO 12004:2-2008 and time-dependent methods. For both investigated materials, the proposed method presents a lower FLC than the others.

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  • 30.
    Tuan Pham, Quoc
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Islam, Md. Shafiqul
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Barlo, Alexander
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Caro, Lluís Pérez
    RISE Research Institutes of Sweden.
    Trana, Kristoffer
    Volvo Cars, Olofström, Sweden.
    Modeling the strain localization of shell elements subjected to combined stretch–bend loads: Application on automotive sheet metal stamping simulations2023Ingår i: Thin-walled structures, ISSN 0263-8231, E-ISSN 1879-3223, Vol. 188, artikel-id 110804Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study presents a modeling approach for predicting strain localization during sheet metal stamping processes focused on automotive engineering applications. The so-called stretching-to-bending ratio, ρ, is proposed to characterize the loading conditions acting on an element during stamping processes. Then, localized strain or necking strain is suggested to be a function of ρ. Different stretch–bending tests with different tool radii, i.e., R3, R6, R10, and R50 are conducted for two automotive sheet metals, DP800 and AA6010, to identify their forming limits under combined stretch–bend loads. The calibrated necking limit curve of the AA6016 sheet is then employed in AutoForm R10 software to predict the necking and failure of a stamped panel. Agreement with the experimental observation of failure positions of the panel validates the usefulness of the proposed modeling approach in practice. © 2023 The Author(s)

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  • 31.
    Tuan Pham, Quoc
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Islam, Md. Shafiqul
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Caro, Lluís Pérez
    RISE Research Institutes of Sweden.
    Lee, Myoung-Gyu
    Seoul National University, South Korea.
    Kim, Young-Suk
    Kyungpook National University, South Korea.
    Improvement of modified maximum force criterion for forming limit diagram prediction of sheet metal2023Ingår i: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 273, artikel-id 112264Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study presents a new criterion (MMFC2) for predicting the forming limit curve (FLC) of sheet metal. The strain path evolution of a critical element examined in a uniaxial tensile test is elaborated by incorporating the results of experimental measurement, finite element simulation, and theoretical prediction via the Modified Maximum Force Criterion (MMFC). A scaling factor is introduced to mimic the theoretical evaluation with the simulated one. It is believed that the rotation of the principal axes of the theoretically considering material point, which is initially co-axial with the external load coordinate, implicates the macro track of the strain path change. Furthermore, an optimal event of the second derivative of the axial rotations is proposed to indicate the strain localization and formulate the FLC. The performance of the proposed criterion is compared with that of the original MMFC in predicting the FLC of three automotive sheet metals, of which all related data were published in the Benchmark of Numisheet 2014 conference. The use of three different hardening laws and three yield functions is examined in the analogy. The comparison reveals that the results of MMFC2 are more sensitive to the employed constitutive model than that of MMFC. Furthermore, the proposed MMFC2 presents concordant results with the experimental data. Nakajima tests are conducted for CR4 mild steel sheets to validate the capacity of the proposed criterion. Well agreement between the experimentally measured data and theoretical prediction based on the Yld2k yield function verifies its usefulness in practice. © 2023 The Author(s)

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  • 32.
    Tuan Pham, Quoc
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Islam, Md. Shafiqul
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Sigvant, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för maskinteknik.
    Lluis Caro, Perez
    Component Manufacturing Unit, Olofström, Sweden.
    Prediction of forming limit diagram of automotive sheet metals using a new necking criterion2023Ingår i: Materials Research Proceedings / [ed] Madej L., Sitko M., Perzynsk K., Materials Research Forum LLC , 2023, Vol. 28, s. 705-710Konferensbidrag (Refereegranskat)
    Abstract [en]

    A theoretical model for predicting the forming limit diagram of sheet metal, namedMMFC2, was recently proposed by the authors based on the modified maximum force criterion(MMFC). This study examines the application of MMFC2 for two automotive sheets, DP800 andAA6016, which are widely used in making car body parts. Uniaxial tensile and bulge tests areconducted to calibrate constitutive equations for modeling the tested materials. The developedmaterial models are employed into different frameworks such as MMFC, MMFC2, and Marciniak-Kuczynski (MK) models to forecast the forming limit curve (FLC) of the tested materials. Theirpredictions are validated by comparing with an experimental one obtained from a series ofNakajima tests. It is found that the derived results of MMFC2 are comparable to that of MK modeland agreed reasonably with experimental data. Less computational time is the major advantage ofMMFC2 against the MK model. (PDF) Prediction of forming limit diagram of automotive sheet metals using a new necking criterion.

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