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  • 1.
    Larsson, Per-Lennart
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Wredenberg, Fredrik
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    On indentation and scratching of thin films on hard substrates2008In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 41, no 7, p. 074022-Article in journal (Refereed)
    Abstract [en]

    Indentation and scratching of thin film/substrate structures, using sharp conical indenters, are studied theoretically and numerically and discussed in particular with material characterization in mind. For simplicity, but not out of necessity, the material behaviour is described by classical elastoplasticity accounting for large deformations. Explicit material parameters are chosen in order to arrive at representative results as regards material behaviour and indenter geometry. The main efforts are devoted towards an understanding of the influence from the film/substrate boundary on global indentation (scratching) properties at different material combinations. Global quantities to be investigated include indentation and scratching hardness, contact area and apparent coefficient of friction at scratching. A comparison of the mechanical behaviour at normal indentation and at scratching is also included. In addition, the behaviour of different field variables is studied and in this case the discussion is focused on fracture initiation governed by a critical stress criterion. The numerical investigation is performed using the finite element method and the numerical strategy is discussed in some detail. Throughout the analysis it is assumed that the substrate is considerably harder than the indented film and consequently the deformation of the substrate is neglected.

  • 2.
    Wredenberg, Fredrik
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Experimental and numerical analysis of scratching of homogeneous materials2006Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Paper A

    Abstract

    A numerical strategy based on the finite element method and intended for an accurate analysis of the scratch test is presented. For simplicity, but not out of necessity,the material was described by classical Mises elastoplasticity utilising large deformation theory. Based on this strategy numerous results are presented and correlation ofscratch properties is discussed within the framework of Johnson (1970, 1985) theoryfor indentation testing. Furthermore, the existence of a representative plastic strainin the spirit of Tabor (1951) was studied. The investigation also concerns details regarding frictional effects, normal vs. tangentional scratch hardness, similarities anddifferences between indentation and scratch test characteristics as well as detailsregarding the behaviour of local field variables at scratching.

    key words: Scratch test, hardness, friction, finite elements, contact

    Paper B

    Abstract

    An experimental and numerical study of the scratch test performed on metals andpolymers was conducted. The materials tested, being both metallic and polymeric,were related to the well known Johnson’s parameter, often used to correlate indentation experiments. The aim was to determine whether it was possible to use the numerical approach presented by Wredenberg and Larsson (2006) to describe the scratch mechanism and of course also to investigate whether or not important scratch quantities can be determined with sufficient accuracy from standard scratch experiments.

    Key words: Scratch test experiments, finite element analysis, contact, metals,

    polymers

  • 3.
    Wredenberg, Fredrik
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Mechanical modelling of surface scratching2008Doctoral thesis, comprehensive summary (Other scientific)
  • 4.
    Wredenberg, Fredrik
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Larsson, Per Lennart
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Experimental and numerical analysis of the scratch test2005In: Computer Methods and Experimental Measurements for Surface Effects and Contact Mechanics VII / [ed] Editor(s): DeHosson, JTM; Brebbia, CA; Nishida, SI, ASHURST: WIT PRESS , 2005, Vol. 49, p. 251-260Conference paper (Refereed)
    Abstract [en]

    A numerical strategy for analysis of the scratch test is presented and verified by experiments. The material is described by standard von Mises plasticity with strain hardening effects utilizing large deformation theory. A parametric study with respect to the well known Johnson's parameter, often used to correlate indentation experiments, was performed numerically and the existence of a representative strain describing important scratch quantities was investigated. The influence of internal friction was also studied.

  • 5.
    Wredenberg, Fredrik
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Larsson, Per Lennart
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    On the stability of delamination growth at scratching of thin film structures2011In: JCT Research, ISSN 1547-0091, E-ISSN 2168-8028, Vol. 8, no 6, p. 707-717Article in journal (Refereed)
    Abstract [en]

    Scratching of thin film/substrate structures is studied theoretically and numerically. The results are discussed in connection to delamination initiation and in particular subsequent growth at scratching. The material behavior of the film is described by classical elastoplasticity accounting for large deformations. The deformation of the substrate is neglected indicating that the results are pertinent to soft thin films. The numerical investigation is performed using the finite element method (FEM) and the numerical strategy is discussed in some detail. The results from this study show that delamination growth at thin film scratching is a stable feature with crack arrest occurring at a decreasing load.

  • 6.
    Wredenberg, Fredrik
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Larsson, Per-Lennart
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Delamination of thin coatings at scratching: Experiments and numerics2009In: Journal of Mechanics of Materials and Structures, ISSN 1559-3959, Vol. 4, no 6, p. 1041-1062Article in journal (Refereed)
    Abstract [en]

    Scratching of thin coatings on hard substrates is studied experimentally and numerically, in the latter case by use of the finite element method. In particular the delamination behaviour at scratching, by increasing the normal load up to failure, is of interest. The adhesion of the coating to the substrate is modelled as a cohesive zone where relevant model parameters are determined experimentally using the double cantilever beam test with uneven bending moments (DCB-UBM). Good correlation between experimental and numerical results were achieved and the most important finding confirms the fact that the delamination behaviour was very much dependent on the critical energy release rate of the film/substrate interface. The results achieved are directly relevant for thin film polymer coatings but can also be applied in more general situations as a comprehensive parameter study is performed using the finite element method.

  • 7.
    Wredenberg, Fredrik
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Larsson, Per-Lennart
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    On scratch testing of pressure-sensitive polymeric coatings2010In: JCT Research, ISSN 1547-0091, E-ISSN 2168-8028, Vol. 7, no 3, p. 279-290Article in journal (Refereed)
    Abstract [en]

    Scratching of polymeric coatings on hard substrates is studied experimentally and numerically from a mechanical point of view. In particular, the behavior of local and global mechanical properties, as well as the delamination behavior, at scratching due to pressure-sensitive effects is of interest. The numerical investigation is performed using the finite element method (FEM) where pressure sensitivity is modeled using the classical Drucker-Prager plasticity model (Drucker, Prager, Q. Appl. Math., 10 157-165 (1952)) while the adhesion of the coating to the substrate is modeled as a cohesive zone where relevant model parameters are determined experimentally using the double cantilever beam test with uneven bending moments (DCB-UBM). Good correlation between experimental and numerical results were achieved and the most important finding concerns the fact that the dependence of pressure sensitivity proved to be different for different mechanical quantities.

  • 8.
    Wredenberg, Fredrik
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Larsson, Per-Lennart
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    On Scratching of Elastic-Plastic Thin Films on Elastic Substrates2011In: Friction, wear and wear protection: International Symposium on Friction, Wear and Wear Protection 2008, Aachen, Germany / [ed] A Fischer, Kirsten Bobzin, Weinheim: Wiley-VCH Verlagsgesellschaft, 2011, p. 321-326Conference paper (Refereed)
  • 9.
    Wredenberg, Fredrik
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Larsson, Per-Lennart
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    On the effect of substrate deformation at scratching of soft thin film composites2010In: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 52, no 7, p. 1008-1014Article in journal (Refereed)
    Abstract [en]

    In the present paper scratching of soft thin film/substrate structures, using sharp conical indenters, is studied theoretically and numerically. For simplicity, but not out of necessity, the material behavior of the film as well as the substrate is described by classical elastoplasticity accounting for large deformations. Explicit material parameters are chosen in order to arrive at representative results as regards material behavior and indenter geometry. The main efforts are devoted towards an understanding of the influence from the film/substrate boundary on global scratching properties at different material combinations. Global quantities to be investigated include scratch hardness, contact area and apparent coefficient of friction at scratching. The numerical investigation is performed using the finite element method (FEM) and the numerical strategy is discussed in some detail. (C) 2010 Elsevier Ltd. All rights reserved.

  • 10.
    Wredenberg, Fredrik
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Larsson, Per-Lennart
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    On the numerics and correlation of scratch testing2007In: Journal of Mechanics of Materials and Structures, ISSN 1559-3959, Vol. 2, no 3, p. 573-594Article in journal (Refereed)
    Abstract [en]

    A numerical strategy based on the finite element method and intended for an accurate analysis of the scratch test is presented. For simplicity, but not out of necessity, the material was described by classical von Mises elastoplasticity utilizing large deformation theory. Based on this strategy numerous results are presented and correlation of scratch properties is discussed within the framework of theory for indentation testing. Furthermore, the existence of a representative plastic strain in the spirit of Tabor was studied. The investigation also concerns details regarding frictional effects, normal vs. tangential scratch hardness, similarities and differences between indentation and scratch test characteristics as well as details regarding the behavior of local field variables at scratching.

  • 11.
    Wredenberg, Fredrik
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Larsson, Per-Lennart
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    On the stress distribution at scratching of thin film structures2010In: JCT Research, ISSN 1547-0091, E-ISSN 2168-8028, Vol. 7, no 5, p. 623-635Article in journal (Refereed)
    Abstract [en]

    Scratching of thin film/substrate structures is studied theoretically and numerically. In most cases, the material behavior of the film as well as the substrate is described by classical elastoplasticity accounting for large deformations; further, pressure-sensitive flow models are considered. The main efforts are devoted toward an understanding of the influence from the film/substrate boundary on the stress distribution at scratching but for comparative reasons, scratching of homogeneous materials are also studied and pertinent results presented. Among other things, the results are discussed in relation to delamination initiation and growth at scratching. The numerical investigation is performed using the finite element method, and the numerical strategy is discussed in some detail. The most important finding given by the present study is that high shear stresses are the main driving force for delamination initiation and growth along the film/substrate interface. It was also noted that the influence from pressure-sensitive flow on the stress fields related to delamination initiation is small, both quantitatively and qualitatively.

  • 12.
    Wredenberg, Fredrik
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Larsson, Per-Lennart
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
    Scratch testing of metals and polymers: Experiments and numerics2009In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 266, no 1-2, p. 76-83Article in journal (Refereed)
    Abstract [en]

    An experimental and numerical study of the scratch test performed on metals and polymers was conducted. The materials tested, being both metallic and polymeric, were related to the well known Johnson's parameter, often used to correlate indentation experiments. The aim was to determine whether it was possible to use the numerical approach presented by Wredenberg and Larsson [F. Wredenberg, P.-L Larsson, On the numerics and correlation of scratch testing, journal of Mechanics of Materials and Structures 2 (2006) 573-594] to describe the scratch mechanism and of course also to investigate whether or not important scratch quantities can be determined with sufficient accuracy from standard scratch experiments.

1 - 12 of 12
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  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
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  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
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  • Other locale
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