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Numerical and experimental investigation of paperboard creasing and folding
KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

 This licentiate thesis aims to increase the understanding of deformation and damage mechanisms of paperboard during converting, especially creasing and folding will be analyzed.

 A simple two dimensional creasing simulation was performed. In this model, paperboard was modeled as a combination of an anisotropic elastic-plastic continuum model with isotropic hardening and a softening cohesive interface model. The paperboard was composed of four plies with uniform material parameters. Creasing simulations were done on both machine direction (MD) and cross machine direction (CD) samples to two crease depths 0.0 mm and 0.2 mm, respectively. The simulation results showed good agreement with experimental results.

 The out-of-plane shear properties are dominating factors for creasing and folding. Therefore, a test method to determine shear properties was proposed. This part of the work is based on the most recently proposed test method, the laminated double notch shear test. To improve the technique, double notches with declined slopes, called tilted double notch shear test, were used instead of uniform depth double notches. The influence of shear zone length was also investigated. The results reveal the short shear zone lengths gave higher shear strength and more pronounced shear strength profile.

 The results from the rst two analyses were utilized to study folding of paperboard. The simulation model was the same as in the creasing simulations. However, to improve the model and better account the actual micro structure of paperboard a new material mapping method was proposed. The continuum properties of the plies were assumed to vary in the thickness direction. The shear strengths of the interfaces were determined by using the tilted double notch shear test using a short shear zone length, L= 5 mm. The agreement between simulation results and experiment results was good, and most of the folding properties were captured.

 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology , 2011. , 28 p.
Series
Trita-HFL. Report / Royal Institute of Technology, Solid Mechanics, ISSN 1654-1472 ; 0503
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-31430OAI: oai:DiVA.org:kth-31430DiVA: diva2:403839
Presentation
2011-03-24, Sal E31, KTH, Lindstedtsvägen 3, Stockholm, 10:15 (English)
Opponent
Supervisors
Note

QC 20110317

Available from: 2011-03-17 Created: 2011-03-15 Last updated: 2013-01-15Bibliographically approved
List of papers
1. A simplified material model for finite element analysis of paperboard creasing
Open this publication in new window or tab >>A simplified material model for finite element analysis of paperboard creasing
2010 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 4, 505-512 p.Article in journal (Refereed) Published
Abstract [en]

A simplified material model to model paperboard was proposed. Paperboard was modeled as a multilayered structure with a softening interface model connecting the paperboard plies. The paperboard plies were modeled using an anisotropic elastic model with a Hill yield surface and isotropic hardening. The model has less material constants than previous models, and the material constants can more easily be determined from uniaxial experiments. The model was tested by performing simulations of creasing of paperboard with a two dimensional finite element model, that mimiced a laboratory creasing device. Creasing experiments and simulations down to two different distances were performed, where the reaction force and displacement of the male ruler were measured. Simulations and experiements were performed both in the paperboard machine direction and cross machine direction. The force-displacement curves from the simulations and experiments were compared, with good agreement.

Keyword
Finite element analysis, Creasing, Paperboard, Mechanical properties
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-30994 (URN)000285701900012 ()2-s2.0-78651382314 (ScopusID)
Note

QC 20110309

Available from: 2011-03-09 Created: 2011-03-07 Last updated: 2016-05-02Bibliographically approved
2. The dependency of shear zone lengh on the shear strength profiles in paperboard
Open this publication in new window or tab >>The dependency of shear zone lengh on the shear strength profiles in paperboard
2011 (English)Report (Other academic)
Abstract [en]

 

In this work, the notched shear strength test (NST) has been further improved. In order to simplify and accelerate the testing procedure, the notches with declined slopes were used. With the proposed procedure, the shear strength profile in the thickness direction of a paperboard can be measured using one sheet only. By using the test setup, the dependency of shear zone length on shear strength was investigated. Experimental results show that both the measured shear strength values as well as the shear strength profile varied significantly with different shear zone length. Longer shear zone gave lower shear strength values and flatter profiles, while a shorter shear zone gave higher strength values and more pronounced shear strength profiles that better followed the paperboard ply structure.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011
Series
TRITA-HFL. Report / Royal Institute of Technology, Solid Mechanics, ISSN 1654-1472 ; 0501
Keyword
out-of-plane, shear test, tilted double notched, lamination, paperboard
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-31512 (URN)
Note

QC 20110317

Available from: 2011-03-17 Created: 2011-03-17 Last updated: 2016-05-25Bibliographically approved
3. Numerical and experimental investigation of paperboard folding
Open this publication in new window or tab >>Numerical and experimental investigation of paperboard folding
2011 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, Vol. 26, no 4, 452-467 p.Article in journal (Refereed) Published
Abstract [en]

Creasing and folding of paperboard are important converting operations in manufacturing of packages. A two-dimensional finite element simulation of multiply paperboard that was creased and folded was presented, and the numerical results were compared with experimental data. The paperboard material model was defined by a combination of an anisotropic elastic-plastic continuum model with isotropic hardening and a softening interface model. Based on experimental observations of variations of properties in the thickness direction of the paperboard, a material mapping method was proposed to define the material parameter in the models. The tilted double notch shear test technique was used to measure the shear strengths for the paperboard interfaces. The material model and data were validated by simulations of the creasing process. Folding simulations were done for both paperboard machine direction and cross machine direction, to two crease depths, 0.0 mm and 0.2 mm. The simulation results were compared with experimental results, where the bending moment-rotation angle curve from the simulation and experiments showed good agreement.

 

Keyword
Folding, Finite element method, Multi-plied paperboard, Creasing
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-31516 (URN)000298868000013 ()
Note
Trita-HFL, ISSN 1104-6813; 0502. QC 20110317Available from: 2011-03-17 Created: 2011-03-17 Last updated: 2013-08-15Bibliographically approved

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