his.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Mixed mode loaded adhesive layers: from measurement of material data to analysis of structural behaviour
University of Skövde, School of Technology and Society.
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In manufacturing of multi-material products, a joining method that is able to cost-effectively assemble components made of dissimilar and similar material, with irregular geometries, is optimal. As an alternative, adhesive bonding is in-creasingly adapted by the industry, which is also used in manufacturing of multi-phase materials. In practice, adhesives are constrained to thin layers. An adhesive as a constrained layer behaves differently compared to the adhesive as a bulk material. In general, adhesive layers are loaded in peel (mode I), or in shear (mode II or III), or in a combination of peel and shear (mixed mode). This thesis deals with mixed mode loaded adhesive layers, from measurement of ma-terial data to analysis of structural behaviour. For studying of structural behaviour of adhesive joints, an integrated approach is developed. Arbitrarily end-loaded single-layer adhesive joints with arbitrary ad-herends of arbitrary length are analysed with the Beam/Adhesive layer (B/A) model. Closed-form solutions are obtained for the adhesive layer as well as for the adherends. For joints with a semi-infinite symmetric geometry, i.e. relative long joints with identical adherends loaded at one end, basic loading cases are obtained. Solutions to these basic loading cases are easy to use in designing of joints with this type of geometry. For nonlinear or general adhesive layers, a mode-dependent cohesive law is de-veloped. The normalized formulation is easy to implement in numerical simula-tions, yet, it captures the characteristics of adhesive layers. For experimental studies, this cohesive law is used to obtain the constitutive behaviour of an adhe-sive layer. The results confirm the ability and suitability of this cohesive law in modelling of adhesive layers. To obtain material data of adhesive layers, experimental methods are developed based on the J-integral. Two specimens, the Mixed mode double Cantilever Beams (MCB) specimen and the Unbalanced Double Cantilever Beams (UDCB) specimen, are designed to allow adhesive layers to be loaded in mixed mode. The MCB-specimen is implemented experimentally and the constitutive behav-iour of the tested adhesive layer is obtained.

Place, publisher, year, edition, pages
Chalmers tekniska högskola , 2007. , 17 p.
Series
Doktorsavhandlingar vid Chalmers tekniska högskola, ISSN 0346-718X ; 2572
Keyword [en]
adhesive layer, mixed mode testing, cohesive law, J-integral
National Category
Mechanical Engineering
Research subject
Technology
Identifiers
URN: urn:nbn:se:his:diva-2039ISBN: 978-91-7291-891-7 OAI: oai:DiVA.org:his-2039DiVA: diva2:32315
Public defence
(English)
Available from: 2008-05-09 Created: 2008-05-09 Last updated: 2013-03-26
List of papers
1. Energy release rate and mode-mixity of adhesive joint specimens
Open this publication in new window or tab >>Energy release rate and mode-mixity of adhesive joint specimens
2007 (English)In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 144, no 4, 267-283 p.Article in journal (Refereed) Published
Abstract [en]

Fracture behaviour of adhesive joints under mixed mode loading is analysed by using the beam/adhesive-layer (b/a) model, in which, the adherends are beamlike and the adhesive is constrained to a thin flexible layer between the adherends. The adhesive layer deforms in peel (mode I), in shear (mode II) or in a combination of peel and shear (mixed mode). Macroscopically, the ends of the bonded part of the joints can be considered as crack tips. The energy release rate of a single-layer adhesive joint is then formulated as a function of the crack tip deformation and the mode-mixity is defined by the shear portion of the total energy release rate. The effects of transversal forces and the flexibility of the adhesive layer are included in the b/a-model, which can be applied to joints with short crack length as well as short bonding length. The commonly used end-loaded unsymmetric semi-infinite joints are examined and closed-form solutions are given. In comparison to the singular-field model in the context of linear elastic fracture mechanics, the b/a-model replaces the singularity at the crack tip with a stress concentration zone. It is shown that the b/a-model and the singular-field model yield fundamentally different mode-mixities for unsymmetric systems. The presented closed-form b/a-model solutions facilitates parametric studies of the influence of unbalance in loading, unsymmetry of the adherends, as well as the flexibility of the adhesive layer, on the mode mixity of an adhesive joint.

Place, publisher, year, edition, pages
Springer, 2007
Keyword
Adhesive layer, Fracture, Energy release rate, Mode-mixity, Beam model
Identifiers
urn:nbn:se:his:diva-2149 (URN)10.1007/s10704-007-9099-9 (DOI)000248978100004 ()
Available from: 2008-06-09 Created: 2008-06-09 Last updated: 2013-04-11Bibliographically approved
2. A closed-form solution to statically indeterminate adhesive joint problems — exemplified on ELS-specimens
Open this publication in new window or tab >>A closed-form solution to statically indeterminate adhesive joint problems — exemplified on ELS-specimens
2008 (English)In: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 28, no 7, 350-361 p.Article in journal (Refereed) Published
Abstract [en]

A beam/adhesive-layer model is developed. For this model a closed-form solution method applicable to arbitrary boundary conditions is presented. This enables the solution of a large number of practical problems which may be statically indeterminate. The stress state in the adhesive layer and the adherends of the beam/adhesive-layer model is also scrutinized. The method is exemplified in an analysis of the end-loaded split (ELS) specimen, commonly used to determine fracture energies of adhesive layers. The effect of the flexibility of the adhesive layer on the energy release rate and the critical crack length for stable crack growth is examined. Both symmetric and unsymmetric ELS-specimens are studied.

Place, publisher, year, edition, pages
Elsevier, 2008
Keyword
C. Fracture mechanics, C. Stress analysis, C. Joint design, Beam/adhesive-layer model
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:his:diva-2528 (URN)10.1016/j.ijadhadh.2007.10.002 (DOI)000256843700003 ()2-s2.0-42949137074 (Scopus ID)
Available from: 2009-01-16 Created: 2009-01-16 Last updated: 2013-04-12Bibliographically approved
3. Specimen proposals for mixed mode testing of adhesive layer
Open this publication in new window or tab >>Specimen proposals for mixed mode testing of adhesive layer
2006 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 73, no 16, 2541-2556 p.Article in journal (Refereed) Published
Abstract [en]

The experimental methods to determine the fracture properties for adhesives under mixed mode loading is not as well established as compared to such methods for adhesives under pure mode loading. Some controversies exist regarding the decomposition of the mode mixity. For a flexible linear elastic adhesive, the mode mixity of a single-layer adhesive joint is directly related to the deformation of the adhesive layer at the crack tip. The governing equations for linear elastic single-layer adhesive joints show that the mode mixity depends on the external loads, the properties of the adherends and often on the flexibility of the adhesive layer. This implies some fundamental problems that have to be addressed before an experimental method can be established. The purpose of this paper is to investigate different specimen configurations for mixed mode loading. Requirements for the design of a specimen configuration are given. A new specimen configuration is proposed based on the geometry of a semi-infinite symmetric DCB-specimen. According to this study, the proposed test specimen offers exceptional flexibility, variety and stability.

Place, publisher, year, edition, pages
Elsevier, 2006
National Category
Engineering and Technology
Research subject
Technology
Identifiers
urn:nbn:se:his:diva-1900 (URN)10.1016/j.engfracmech.2006.04.017 (DOI)000240837000023 ()2-s2.0-33747202424 (Scopus ID)
Available from: 2008-01-09 Created: 2008-01-09 Last updated: 2013-04-10Bibliographically approved
4. Constitutive behaviour of mixed mode loaded adhesive layer
Open this publication in new window or tab >>Constitutive behaviour of mixed mode loaded adhesive layer
2007 (English)In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 44, no 25-26, 8335-8354 p.Article in journal (Refereed) Published
Abstract [en]

Mixed mode testing of adhesive layer is performed with the Mixed mode double Cantilever Beam specimen. During the experiments, the specimens are loaded by transversal and/or shear forces; seven different mode mixities are tested. The J-integral is used to evaluate the energy dissipation in the failure process zone. The constitutive behaviour of the adhesive layer is obtained by a so called inverse method and fitting an existing mixed mode cohesive model, which uses a coupled formulation to describe a mode dependent constitutive behaviour. The cohesive parameters are determined by optimizing the parameters of the cohesive model to the experimental data. A comparison is made with the results of two fitting procedures. It is concluded that the constitutive properties are coupled, i.e. the peel and shear stress depend on both the peel and shear deformations. Moreover, the experiments show that the critical deformation in the peel direction is virtually independent of the mode mixity.

Place, publisher, year, edition, pages
Elsevier, 2007
Keyword
Adhesive layer, Mixed mode testing, J-integral, Constitutive behaviour, Cohesive law, Inverse method
National Category
Condensed Matter Physics
Research subject
Technology
Identifiers
urn:nbn:se:his:diva-2529 (URN)10.1016/j.ijsolstr.2007.06.014 (DOI)000251775400016 ()2-s2.0-35448969787 (Scopus ID)
Available from: 2009-01-16 Created: 2009-01-16 Last updated: 2013-04-11Bibliographically approved
5. Mixed mode cohesive law
Open this publication in new window or tab >>Mixed mode cohesive law
2006 (English)In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 141, no 3-4, 549-559 p.Article in journal (Refereed) Published
Abstract [en]

A traction-separation relation to model the fracture process is presented. The cohesive law captures the linear elastic and softening behaviour prior to fracture. It also allows for different fracture parameters, such as fracture energy, strength and critical separation in different mode mixities. Thus, the fracture process in mode I (peel), in mode II (shear) or in mixed mode (a combination of peel and shear) can be modelled without the limitation of a common fracture energy in peel and shear. Examples are given in form of FE- implementations of the normalised cohesive law, namely for the Unsymmetrical Double Cantilever Beam (UDCB) specimen and the Mixed-mode double Cantilever Beam (MCB) specimen. Both specimens are adhesively bonded and loaded in mixed-mode

Place, publisher, year, edition, pages
Springer Netherlands, 2006
Keyword
Cohesive law, Fracture energy, Traction-separation relation, Mixed mode
National Category
Engineering and Technology
Research subject
Technology
Identifiers
urn:nbn:se:his:diva-1971 (URN)10.1007/s10704-006-9014-9 (DOI)000243181600013 ()2-s2.0-33751116800 (Scopus ID)
Available from: 2008-04-16 Created: 2008-04-16 Last updated: 2013-04-10Bibliographically approved
6. Unbalanced UCB-specimen
Open this publication in new window or tab >>Unbalanced UCB-specimen
2006 (English)In: CDCM06 online proceedings, University of Stuttgart , 2006Conference paper, (Refereed)
Abstract [en]

The Double Cantilever Beam (DCB) specimen is a common test geometry for testing of mode I fracture properties of adhesive joints. However, when unbalances are introduced to the adherends, the adhesive layer is loaded in a combination of peel (mode I) and shear (mode II). In this work the unbalanced DCB-specimen is studied by the use of the beam/adhesive layer (B/A) model, in which the adherends are considered as beams and the adhesive layer as a generalised spring media. The effect of the thickness of adhesive layer together with the effect of the geometrical and material unbalances is analysed. The result of the B/A model is compared to the continuum model through FE-simulations. Finally, an unsymmetric DCB-specimen is dimensioned for mixed mode testing of adhesive layer.

Place, publisher, year, edition, pages
University of Stuttgart, 2006
Keyword
adhesive layer; mixed mode testing, Double Cantilever Beam specimen
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:his:diva-2545 (URN)3-930683-90-3 (ISBN)
Available from: 2009-01-19 Created: 2009-01-19 Last updated: 2013-03-20

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Högberg, Jia Li
By organisation
School of Technology and Society
Mechanical Engineering

Search outside of DiVA

GoogleGoogle Scholar

Total: 425 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf