Endre søk
Begrens søket
1 - 16 of 16
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Alizadeh-Khameneh, Mohammad Amin
    et al.
    KTH Royal Institute of Technology, Division of Geodesy and Satellite Positioning, Stockholm, Sweden.
    Eshagh, Mehdi
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Jensen, Anna O.
    KTH Royal Institute of Technology, Division of Geodesy and Satellite Positioning, Stockholm, Sweden.
    Optimization of deformation monitoring networks using finite element strain analysis2018Inngår i: Journal of Applied Geodesy, ISSN 1862-9016, E-ISSN 1862-9024, Vol. 2, nr 2, s. 187-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An optimal design of a geodetic network can fulfill the requested precision and reliability of the network, and decrease the expenses of its execution by removing unnecessary observations. The role of an optimal design is highlighted in deformation monitoring network due to the repeatability of these networks. The core design problem is how to define precision and reliability criteria. This paper proposes a solution, where the precision criterion is defined based on the precision of deformation parameters, i. e. precision of strain and differential rotations. A strain analysis can be performed to obtain some information about the possible deformation of a deformable object. In this study, we split an area into a number of three-dimensional finite elements with the help of the Delaunay triangulation and performed the strain analysis on each element. According to the obtained precision of deformation parameters in each element, the precision criterion of displacement detection at each network point is then determined. The developed criterion is implemented to optimize the observations from the Global Positioning System (GPS) in Skåne monitoring network in Sweden. The network was established in 1989 and straddled the Tornquist zone, which is one of the most active faults in southern Sweden. The numerical results show that 17 out of all 21 possible GPS baseline observations are sufficient to detect minimum 3 mm displacement at each network point. © 2018 Walter de Gruyter GmbH, Berlin/Boston.

  • 2.
    Azar, Amin S.
    et al.
    SINTEF Mat & Chem, Oslo, Norway.
    Svensson, Lars-Erik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Nyhus, Bård
    SINTEF Mat & Chem, Oslo, Norway.
    Effect of crystal orientation and texture on fatigue crack evolution in high strength steel welds2015Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 77, s. 95-104Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study, electron backscattered diffraction is used to analyze the fatigue crack evolution in a high strength steel weld that was loaded cyclically in the plastic regime. Three prominent regions of a fatigue crack are investigated separately: crack tip, crack trajectory and crack initiation. Taylor and Schmid factors are mapped with respect to the defined loading matrix. Possible effective mechanisms are proposed based on the local plasticity properties like lattice rotation and misorientation. The analyses of the crack tip and trajectory regions show that although the critical resolved shear stresses in some regions are low, small deformation resistance of these regions can compromise the dislocation immobility and cause local fracture. It is shown that if the crack grows transgranularly, at least one side of the crack may show low lattice rotation or strain equivalent values, which indicates the relaxation of elastic stresses after fracture. The crack initiation is determined to be dominantly controlled by transcrystalline mechanism of initiation that takes place under plastic loading conditions. It is also shown that the secondary < 123 >11 (1) over bar type of slip systems were the most activated under such loading conditions. (C) 2015 Elsevier Ltd. All rights reserved.

  • 3.
    Beaubert, F.
    et al.
    TEMPO, UVHC, Campus Mont Houy, 59313 Valenciennes Cedex 9, France.
    Pálsson, H.
    University of Iceland, Sæmundargötu 2, Reykjavík 101, Iceland.
    Lalot, S.
    EMPO, UVHC, Campus Mont Houy, Valenciennes Cedex 9, France.
    Choquet, Isabelle
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Bauduin, H.
    EMPO, UVHC, Campus Mont Houy, Valenciennes Cedex 9, France.
    Fundamental mode of freely decaying laminar swirling flows2016Inngår i: Applied Mathematical Modelling, ISSN 0307-904X, E-ISSN 1872-8480, Vol. 40, nr 13-14, s. 6218-6233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract A detailed study of a swirling flow in a tube is presented in the first part of the paper. A simplified analytical solution of the governing equations indicates specific modes of the tangential velocity and that the decay of the swirl effect is exponential. The problem is then solved in three dimensions using computational fluid dynamics (CFD) and a comparison with analytical expressions shows that the CFD code is reliable in terms of accuracy. The CFD results confirm that a fundamental swirling mode is reached within a short distance from the inlet. The torque swirl number is introduced to physically estimate the intensity of the swirl. A companion value is given: it is the average deviation.

  • 4.
    Broberg, Patrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för process- och produktutveckling.
    Towards Automation of Non-Destructive Testing of Welds2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    All welding processes can give rise to defects that will weaken the joint and can lead to failure of the welded structure. Because of this, non-destructive testing (NDT) of welds have become increasingly important to ensure the structural integrity when the material becomes thinner and stronger and welds become smaller; all to reduce weight in order to save material and reduce emissions due to lighter constructions.

    Several NDT methods exists for testing welds and they all have their advantages and disadvantages when it comes to the types and sizes of defects that are detectable, but also in the ability to automate the method. Several methods were compared using common weld defects to determine which method or methods were best suited for automated NDT of welds. The methods compared were radiography, phased array ultrasound, eddy current, thermography and shearography. Phased array ultrasound was deemed most suitable for detecting the weld defects used in the comparison and for automation and was therefore chosen to be used in the continuation of this work. Thermography was shown to be useful for detecting surface defects; something not easily detected using ultrasound. A combination of these techniques will be able to find most weld defects of interest.

    Automation of NDT can be split into two separate areas; mechanisation of the testing and automation of the analysis, both presenting their own difficulties. The problem of mechanising the testing has been solved for simple geometries but for more general welds it will require a more advance system using an industrial robot or similar. Automation of the analysis of phased array ultrasound data consists of detection, sizing, positioning and classification of defects. There are several problems to solve before a completely automatic analysis can be made, including positioning of the data, improving signal quality, segmenting the images and classifying the defects. As a step on the way towards positioning of the data, and thereby easing the analysis, the phase of the signal was studied. It was shown that the phase can be used for finding corners in the image and will also improve the ability to position the corner as compared to using the amplitude of the signal. Further work will have to be done to improve the signal in order to reliably analyse the data automatically.

  • 5.
    Eggertsen, P. -A
    et al.
    University of Technology, Div. of Material and Computational Mechanics, Dept. of Applied Mechanics Chalmers.
    Mattiasson, Kjell
    University of Technology, Div. of Material and Computational Mechanics, Dept. of Applied Mechanics Chalmers.
    Larsson, Mats
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för maskinteknik.
    A comprehenisve analysis of benchmark 4: Pre-strain effect on springback of 2D draw bending2011Inngår i: AIP Conference Proceedings, Seoul, 2011, Vol. 1383, s. 1064-1071Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In order to be able to form high strength steels with low ductility, multi-step forming processes are becoming more common. Benchmark 4 of the NUMISHEET 2011 conference is an attempt to imitate such a process. A DP780 steel sheet with 1.4 mm thickness is considered. In order to understand the pre-strain effect on subsequent forming and springback, a 2D draw-bending is considered. Two cases are studied: one without prestrain and one with 8% pre-stretching. The draw-bending model is identical to the "U-bend" problem of the NUMISHEET'93 conference. The purpose of the benchmark problem is to evaluate the capability of modern FE-methods to simulate the forming and springback of these kinds of problems. The authors of this article have previously made exhaustive studies on material modeling in applications to sheet metal forming and springback problems, [1],[2],[3]. Models for kinematic hardening, anisotropic yield conditions, and elastic stiffness reduction have been investigated. Also procedures for material characterization have been studied. The material model that mainly has been used in the current study is based on the Banabic BBC2005 yield criterion, and a modified version of the Yoshida-Uemori model for cyclic hardening. This model, like a number of other models, has been implemented as User Subroutines in LS-DYNA. The effects of various aspects of material modeling will be demonstrated in connection to the current benchmark problems. The provided material data for the current benchmark problem are not complete in all respects. In order to be able to perform the current simulations, the authors have been forced to introduce a few additional assumptions. The effects of these assumptions will also be discussed. © 2011 American Institute of Physics.

  • 6.
    Eynian, Mahdi
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Magnevall, Martin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Sandvik Coromant AB, Sandviken, 81181, Sweden.
    Cedergren, Stefan
    GKN Aerospace Sweden AB, Trollhättan, 46138, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Trollhättan, 46138, Sweden.
    Lundblad, Mikael
    Sandvik Coromant AB, Sandviken, 81181, Sweden.
    New methods for in-process identification of modal parameters in milling2018Inngår i: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 77, s. 469-472Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Chatter vibrations encountered in machining can degrade surface finish and damage the machining hardware. Since chatter originates from unstable interaction of the machining process and the machining structure, information about vibration parameters of the machining structure should be used to predict combinations of cutting parameters that allow stable machining. While modal test methods, for example those with impact hammers, are widely used to identify structural parameters; the need for sophisticated test equipment is prohibitive in their use. Furthermore, dynamic properties of critical components of a machine tool may change as they get affected by cutting loads, material removal and spindle rotation. Recently few algorithms have been proposed that identify the in-process dynamic parameters by frequency measurements, thus avoiding these problems. In this paper, some of these algorithms are reviewed and their capabilities and limitations in processing am experimental data set are compared and discussed. © 2018 The Authors. Published by Elsevier Ltd.

  • 7.
    Guevara-Garca, Alfredo
    et al.
    McMaster University, Department of Chemistry and Chemical Biology.
    Echegaray, Eleonora
    Pontificia Universidad Catlica de Chile, Facultad de Qumica, Laboratorio de Qumica Terica Computacional (QTC).
    Toro-Labbe, Alejandro
    Pontificia Universidad Catlica de Chile, Facultad de Qumica, Laboratorio de Qumica Terica Computacional (QTC).
    Jenkins, Samantha
    Högskolan Väst, Institutionen för ekonomi och it, Avd för datavetenskap och informatik.
    Kirk, Steven R.
    Högskolan Väst, Institutionen för ekonomi och it, Avd för datavetenskap och informatik.
    Ayers, Paul W.
    McMaster University, Department of Chemistry and Chemical Biology.
    Pointing the way to the products Comparison of the stress tensor and the second-derivative tensor of the electron density2011Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 134, nr 23, s. 234106-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The eigenvectors of the electronic stress tensor can be used to identify where new bond paths form in a chemical reaction. In cases where the eigenvectors of the stress tensor are not available, the gradient-expansion- approximation suggests using the eigenvalues of the second derivative tensor of the electron density instead; this approximation can be made quantitatively accurate by scaling and shifting the second-derivative tensor, but it has a weaker physical basis and less predictive power for chemical reactivity than the stress tensor. These tools provide an extension of the quantum theory of atoms and molecules from the characterization of molecular electronic structure to the prediction of chemical reactivity. © 2011 American Institute of Physics.

  • 8.
    Javidi Shirvan, Alireza
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för maskinteknik.
    Modelling of Electric Arc Welding: arc-electrode coupling2013Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Arc welding still requires deeper process understanding and more accurateprediction of the heat transferred to the base metal. This can be provided by CFD modelling.Most works done to model arc discharge using CFD consider the arc corealone. Arc core simulation requires applying extrapolated experimental data asboundary conditions on the electrodes. This limits the applicability. To become independent of experimental input the electrodes need to be included in the arcmodel. The most critical part is then the interface layer between the electrodesand the arc core. This interface is complex and non-uniform, with specific physicalphenomena.The present work reviews the concepts of plasma and arc discharges that areuseful for this problem. The main sub-regions of the model are described, andtheir dominant physical roles are discussed.The coupled arc-electrode model is developed in different steps. First couplingsolid and fluid regions for a simpler problem without complex couplinginterface. This is applied to a laser welding problem using the CFD softwareOpenFOAM. The second step is the modelling of the interface layer betweencathode and arc, or cathode layer. Different modelling approaches available inthe literature are studied to determine their advantages and drawbacks. One ofthem developed by Cayla is used and further improved so as to satisfy the basicprinciples of charge and energy conservation in the different regions of thecathode layer. A numerical procedure is presented. The model, implementedin MATLAB, is tested for different arc core and cathode conditions. The maincharacteristics calculated with the interface layer model are in good agreementwith the reference literature. The future step will be the implementation of theinterface layer model in OpenFOAM.

  • 9.
    Javidi Shirvan, Alireza
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Choquet, Isabelle
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    A review of cathode-arc coupling modeling in GTAW2016Inngår i: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 60, nr 4, s. 821-835Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Material properties of welds are strongly influenced by the thermal history, including the thermo-fluid and electromagnetic phenomena in the weld pool and the arc heat source. A necessary condition for arc heat source models to be predictive is to include the plasma column, the cathode, and the cathode layer providing their thermal and electric coupling. Different cathode layer models based on significantly different physical assumptions are being used. This paper summarizes today’s state of the art of cathode layer modeling of refractory cathodes used in GTAW at atmospheric pressure. The fundamentals of the cathode layer and its physics are addressed. The main modeling approaches, namely (i) the diffusion approach, (ii) the partial LTE approach, and (iii) the hydrodynamic approach are discussed and compared. The most relevant publications are systematically categorized with regard to the respective physical phenomena addressed. Results and process understanding gained with these models are summarized. Finally, some open questions are underlined.

  • 10.
    Odenberger, Eva-Lis
    et al.
    Luleå University of Technology, Division of Mechanics of Solid Materials, Luleå, SE-971 87, Sweden; Division Materials and Production, RISE IVF AB, RISE Research Institutes of Sweden, Vällaregatan 30, Olofström, SE-293 38, Sweden.
    Pederson, Robert
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Oldenburg, Mats
    Luleå University of Technology, Division of Mechanics of Solid Materials, Luleå, SE-971 87, Sweden.
    Finite element modeling and validation of springback and stress relaxation in the thermo-mechanical forming of thin Ti-6Al-4V sheets2019Inngår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 104, nr 9-12, s. 3429-3455Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, a hot forming procedure is developed using computer-aided engineering (CAE) to produce thin Ti-6Al-4V sheet components in an effective way. Traditional forming methods involve time- and cost-consuming furnace heating and subsequent hot sizing steps. A material model for finite element (FE) analyses of sheet metal forming and springback at elevated temperatures in Ti-6Al-4V is calibrated and evaluated. The anisotropic yield criterion proposed by Barlat et al. 2003 is applied, and the time- and temperature-dependent stress relaxation behavior for elastic and inelastic straining are modeled using a Zener–Wert–Avrami formulation. Thermo-mechanical uniaxial tensile tests, a biaxial test, and uniaxial stress relaxation tests are performed and used as experimental reference to identify material model parameters at temperatures up to 700 °C. The hot forming tool setup is manufactured and used to produce double-curved aero engine components at 700 °C with different cycle times for validation purposes. Correlations between the predicted and measured responses such as springback and shape deviation show promising agreement, also when the forming and subsequent holding time was as low as 150 s. The short cycle time resulted in elimination of a detectable alpha case layer. Also, the tool surface coating extends the tool life in combination with a suitable lubricant. © 2019, The Author(s).

  • 11.
    Segerstark, Andreas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för maskinteknik.
    Weld head motion control of girth and tubular joint welding simulations in LS-DYNA2013Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    The basis for performing a thermo-mechanical staggered coupled heat source analysis of a welding simulation is implemented into LS-DYNA. In this report, three methods for initiating the heat source’s mechanical motion during girth and tubular joint welding are developed and evaluated. The first method is a reformulation of the equations used at Det Norske Veritas, the second is an incorporation of the equations into excel and the third is a standalone third party software. The most efficient of the developed methods turned out to be the software which creates k-files which are implemented into the main k-file using LS-PrePost. All methods have been visually and numerically evaluated using Excel, LS-DYNA and LS-PrePost.

  • 12.
    Steffenburg-Nordenström, Joachim
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). GKN Aerospace Sweden.
    The evolution of residual stresses in a stress relief heat treatment of test specimen of alloy 7182016Inngår i: Mathematical Modelling of Weld Phenomena 11 / [ed] S. Sommitsch, N. Enzinger, P. Mayr, Graz, 2016, Vol. 11, s. 331-343Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Manufacturing of aero engine components requires attention to residual stress and final shape of the product in order to meet high quality product standards. This sets very high demands on involved manufacturing steps to meet design requirements. Simulations are used to assure the latter. This requires an appropriate model to account for stress relaxation. The study is part of a project where the aim is to simulate a chain of manufacturing steps e.g. forming, welding and heat treatment. The focus in this paper is on the stress relaxation during the heat treatment step. It is imperative to have relevant data for calibrating this part of a constitutive model.  A test procedure resembling the real conditions in the manufacturing chain is proposed. Tests were carried out on test specimens made of Alloy718 and used to calibrate a constitutive model. Comparisons between experimental and simulated results showed very good agreement.

  • 13.
    Steffenburg-Nordenström, Joachim
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). GKN Aerospace Sweden.
    Pérez Caro, Lluís
    IUC, Olofström, Sweden.
    Odenberger, Eva-Lis
    IUC, Olofström, Sweden.
    Oldenburg, Mats
    Luleå University of technology, Luleå, Sweden.
    Svensson, Lars-Erik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Comparison of forming, welding and heat treatment simulations in LS-DYNA and MSC Marc2016Inngår i: Proceedings of 10th International Conference on Trends in  Welding Research & 9th International Welding Symposium of Japan Welding, American Welding Society (AWS) & Japan Welding Society (JWS) , 2016, s. 660-663Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The manufacturing of components for aero engine structures from a flat sheet to the final shape usually requires several steps that may introduce residual stresses and shape distortions in the part. Depending on the magnitude, sign and distribution with respect to the stresses induced by the service load, the remaining stresses may affect the service life of a component, especially when submitted to cyclic loading. Nowadays, several types of software that have the ability to predict the residual stresses and the final shape of a component subjected to various process steps are available. However, literature shows a lack of comparison studies among different software tools for multi-step simulations of a manufacturing process. In this study, the manufacturing process chain of an aerospace component including forming, welding and heat treatment in the nickel-based superalloy 718 is modelled and simulated using the two finite element software codes LS-DYNA and MSC.Marc. The results from the displacement of the blank in the punch stroke direction, the equivalent plastic strain and the von Mises stress are compared between both FE codes. The displacement of the blank after forming is slightly higher in LS-DYNA compared to MSC.Marc, as well as the equivalent plastic strain and the von Mises stress values. This tendency is also observed after trimming and welding. It can also be noted that the distribution of both strains and stresses on the trimmed and welded parts varies between the two compared codes, presumably due to the choice of different solver options, explicit and implicit.

  • 14.
    Svenungsson, Josefine
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Choquet, Isabelle
    Högskolan Väst, Institutionen för teknik, matematik och datavetenskap, Avd för maskinteknik.
    Kaplan, Alexander F.H.
    Luleå University of Technology, Department of Engineering Science and Mathematics, 971 87 Luleå, Sweden.
    Laser Welding Process: A  Review of Keyhole Welding Modelling2015Inngår i: Physics Procedia, ISSN 1875-3892, E-ISSN 1875-3892, Vol. 78, s. 182-191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Laser welding is used in several industrial applications. It can be distinguished between conduction mode and keyhole mode welding, between pulsed wave and cw laser welding and between CO2-lasers with a wavelength of 10 μm and various laser types of about 1 μm wavelength. A deeper understanding of laser welding allows improving weld quality, process control and process efficiency. It requires a complementary combination of precise modelling and experimental investigations. The here presented review focuses on modelling of laser keyhole welding, for both wavelength regimes. First, the fundamentals of the laser welding process and its physics such as beam propagation, keyhole formation and melt pool dynamics are addressed. The main approaches for modeling energy transfer from laser beam to keyhole surface as well as fluid flow in the material are then discussed. The most relevant publications are systematically structured, particularly categorized with regard to the respective physical phenomena addressed. Finally some open questions are underlined.

  • 15.
    Wiklund, Daniel
    et al.
    Swerea IVF, Box 104, Mölndal, SE-431 22, Sweden.
    Larsson, Mats
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Phenomenological friction model in deep drawing of aluminum sheet metals2018Inngår i: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 418, nr 1, s. 1-8, artikkel-id 012097Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Friction is an important parameter in sheet metal forming since it influences the flow of material in the process. Consequently, it is also an important parameter in the design process of new stamping dies when numerical simulations are utilized. Today, the most commonly used friction model in forming simulations is Coulomb’s friction which is a strong simplification of the tribological system conditions and a contributory cause of discrepancy between simulation and physical experiments. There are micromechanical models available but with an inherent complexity that results in limited transparency for users. The objective in this study was to design a phenomenological friction model with a natural level of complexity when Coulomb’s friction is inadequate. The local friction model considers implicit properties of tool and sheet surface topography, lubricant viscosity, sheet metal hardness and strain, and process parameters such as sliding speed and contact pressure. The model was calibrated in a Bending-Under-Tension test (BUT) and the performance was evaluated in a cross shaped geometry (X-die). The results show a significant improvement of the simulation precision and provide the user a transparent tribological system. © Published under licence by IOP Publishing Ltd.

  • 16.
    Åstrand, Erik
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). Volvo Construction Equipment AB, Braås, Sweden .
    Stenberg, T.
    Royal Institute of Technology (KTH), Department of Aeronautical and Vehicle Engineering, Division of Lightweight Structures, Stockholm, Sweden .
    Jonsson, B.
    Volvo Construction Equipment AB, Braås, Sweden .
    Barsoum, Z.
    Royal Institute of Technology (KTH), Department of Aeronautical and Vehicle Engineering, Division of Lightweight Structures, Stockholm, Sweden .
    Welding procedures for fatigue life improvement of the weld toe2016Inngår i: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 60, nr 3, s. 573-580Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents the results of an experimental study of gas metal arc welded, GMAW, cruciform joints made of common construction steel S355. The hypothesis is that smooth undercuts in as welded conditions can give enhanced fatigue properties similarly as post treated welds. Undercuts are generally seen as a defect or imperfection. Welders try to avoid these and repair them when they occur, which result in increased production lead time. Post weld improvement methods i.e. grinding or high-frequency-impact treatment (HFMI) as fatigue-enhancing post-treatment methods enforce amongst other effects a certain smooth undercut-shaped groove in the treated weld toe region. The obtained shallower weld toe transition reduces the geometrical notch effect and increases fatigue strength. This paper presents a study whereas welded specimens with a weld toe geometry similar to what is obtained by weld toe grinding or HFMI-treatment, has been produced, fatigue tested and analyzed. The improvement of the fatigue strength is comparable to post-weld treated specimens. It has proven to be an efficient way to achieve high-quality welds without introducing any additional operations in production, thus enabling weight reduction using cost-effective methods.

1 - 16 of 16
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf