Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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
Micromechanical Behavior of Fiber Networks
KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Paper is used in a wide range of applications, each of which has specific requirements on mechanical and surface properties. The role of paper strength on paper performance is still not well understood. This work addresses the mechanical properties of paper by utilizing fiber network simulation and consists of two parts.In the first part, we use a three-dimensional model of a network of fibers to describe the fracture process of paper accounting for nonlinearities at the fiber level (material model and geometry) and bond failures. A stress-strain curve of paper in tensile loading is described with the help of the network of dry fibers; the parameters that dominate the shape of this curve are discussed. The evolution of network damage is simulated, the results of which are compared with digital speckle photography experiments on laboratory sheets. It is concluded that the original strain inhomogeneities due to the structure are transferred to the local bond failure dynamics. The effects of different conventional and unconventional bond parameters are analyzed. It has been shown that the number of bonds in paper is important and that the changes in bond strength influence paper mechanical properties significantly.In the second part, we proposed a constitutive model for a fiber suitable for cyclic loading applications. We based the development of the available literature data and on the detailed finite-element model of pulp fibers. The model provided insights into the effects of various parameters on the mechanical response of the pulp fibers. The study showed that the change in the microfibril orientation upon axial straining is mainly a geometrical effect and is independent of material properties of the fiber as long as the deformations are elastic. Plastic strains accelerate the change in microfibril orientation. The results also showed that the elastic modulus of the fiber has a non-linear dependency on a microfibril angle,with elastic modulus being more sensitive to the change of microfibril angle around small initial values of microfibril angles. These effects were incorporated into a non-linear isotropic hardening plasticity model for beams and tested in a fiber network in cycling loading application model, using the model we estimated the level of strains that fiber segments accumulate at the failure point in a fiber network.The main goal of this work is to create a tool that would act as a bridge between microscopic characterization of fiber and fiber bonds and the mechanical properties that are important in the papermaking industry. The results of this work provide a fundamental insight on mechanics of paper constituents in tensile as well as cyclic loading. This would eventually lead to a rational choice of raw materials in paper manufacturing and thus utilizing the environment in a balanced way.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , 22 p.
Series
Trita-HFL. Report / Royal Institute of Technology, Solid Mechanics, ISSN 1654-1472 ; 0542
Keyword [en]
Network simulation, Mechanical properties, Fibers, Bonds, Paper properties, Damage, Microfibril angle, Torsion
National Category
Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:kth:diva-123223ISBN: 978-91-7501-789-1 (print)OAI: oai:DiVA.org:kth-123223DiVA: diva2:625513
Presentation
2013-06-10, Seminarierummet, Teknikringen 8D, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20130605

Available from: 2013-06-05 Created: 2013-06-05 Last updated: 2013-06-05Bibliographically approved
List of papers
1. Stress-strain curve of paper revisited
Open this publication in new window or tab >>Stress-strain curve of paper revisited
2012 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, 318-328 p.Article in journal (Refereed) Published
Abstract [en]

We have investigated a relation between micromechanical processes and the stress-strain curve of a dry fiber network during tensile loading. By using a detailed particle-level simulation tool we investigate, among other things, the impact of "non-traditional" bonding parameters, such as compliance of bonding regions, work of separation and the actual number of effective bonds. This is probably the first three-dimensional model which is capable of simulating the fracture process of paper accounting for nonlinearities at the fiber level and bond failures. The failure behavior of the network considered in the study could be changed significantly by relatively small changes in bond strength, as compared to the scatter in bonding data found in the literature. We have identified that compliance of the bonding regions has a significant impact on network strength. By comparing networks with weak and strong bonds, we concluded that large local strains are the precursors of bond failures and not the other way around.

Keyword
Network simulation, Mechanical properties, Fibers, Bonds, Paper properties, Damage
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-104884 (URN)10.3183/NPPRJ-2012-27-02-p318-328 (DOI)000315696000021 ()2-s2.0-84865252133 (Scopus ID)
Note

QC 20121114

Available from: 2012-11-14 Created: 2012-11-14 Last updated: 2017-12-07Bibliographically approved
2. Constitutive modelling of a paper fibre in cyclic loading applications
Open this publication in new window or tab >>Constitutive modelling of a paper fibre in cyclic loading applications
2013 (English)Report (Other academic)
Series
Trita-HFL. Report / Royal Institute of Technology, Solid Mechanics, ISSN 1654-1472 ; 541
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-123234 (URN)
Note

QC 20130605

Available from: 2013-06-05 Created: 2013-06-05 Last updated: 2013-06-05Bibliographically approved

Open Access in DiVA

fulltext(977 kB)306 downloads
File information
File name FULLTEXT01.pdfFile size 977 kBChecksum SHA-512
f8c1b7767d41645928be128b48b18b446d4e6ad46fe5894dd0b9c717c9d4d0e4fe7ec90be977fbc7921ee12d77e68bb731fd0c2acf76154954e2097cd2ca857e
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Borodulina, Svetlana
By organisation
Solid Mechanics (Div.)
Paper, Pulp and Fiber Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 306 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 639 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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