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In-plane fracture analysis of paperboard using x-ray tomography

Andersson, Daniel LU and Hedberg, Olof (2018) In ISRN LUTFD2/TFHF-18/5223-SE FHLM01 20172
Solid Mechanics
Abstract
In this Master's Thesis x-ray tomography was used during tensile experiments on paperboard to study delamination and cohesive failure. Digital volume correlation of
the x-ray tomograph images enabled quantitative analysis of strain fields.

Tensile experiments on different specimen geometries were also conducted to investigate how the geometry affected the response of the specimens during loading. By
analysing the size effects and by using normalisation it was found that the behaviour
of the material during tensile experiments was independent of the geometry. Using
x-ray tomography images, a thickness increase was measured, all the way from loading
start to sample failure. It was found that right before the failure strength, the... (More)
In this Master's Thesis x-ray tomography was used during tensile experiments on paperboard to study delamination and cohesive failure. Digital volume correlation of
the x-ray tomograph images enabled quantitative analysis of strain fields.

Tensile experiments on different specimen geometries were also conducted to investigate how the geometry affected the response of the specimens during loading. By
analysing the size effects and by using normalisation it was found that the behaviour
of the material during tensile experiments was independent of the geometry. Using
x-ray tomography images, a thickness increase was measured, all the way from loading
start to sample failure. It was found that right before the failure strength, the material
experienced a higher dilation compared to during the rest of the experiment. It was
further found, using digital volume correlation, that the normal strains in the loading
direction localised in parabolic zones with higher strains between the notches in the
test sample. From the shear strain fields it was also noted that in close proximity to
the failure strength, shear strains increased.

The thickness increase right before failure was probably caused by delamination of
the paperboard. However, even though delamination results in dilation of the sample
it was proven, by performing tensile tests on pre-delaminated samples, that it does
not affect the cohesive failure. This means that delamination does not cause in-plane
failure. From the analysis it was instead observed that the in-plane failure occurs at
the zones with higher strains in the loading direction.

During this Master's Thesis it was found that the combination of x-ray tomography and digital volume correlation is effective to gain more information about the
internal structure and deformation of paperboard. (Less)
Popular Abstract
Paperboard undergoes changes in its mechanical properties when subjected to loading. To increase the
knowledge about the mechanisms active during loading, it is of interest to understand how the internal
structure of paperboard evolves. It was found that neither sample geometry nor delamination within
the paperboard affect the cohesive failure. One observed mechanism during tensile loading was a
thickness increase immediately after load was applied. The thickness increase continued during the
experiment, and resulted in delamination close to failure. In addition, when analysing the normal
strain-field in the loading direction, localisation of zones with higher strains were observed.
Please use this url to cite or link to this publication:
author
Andersson, Daniel LU and Hedberg, Olof
supervisor
organization
course
FHLM01 20172
year
type
H3 - Professional qualifications (4 Years - )
subject
keywords
paperboard, x-ray tomography, digital volume correlation, dvc, strain field, size effect, tensile experiment, strain rate
publication/series
ISRN LUTFD2/TFHF-18/5223-SE
report number
5223
language
English
id
8935651
date added to LUP
2018-02-14 15:28:48
date last changed
2018-02-14 15:28:48
@misc{8935651,
  abstract     = {In this Master's Thesis x-ray tomography was used during tensile experiments on paperboard to study delamination and cohesive failure. Digital volume correlation of
the x-ray tomograph images enabled quantitative analysis of strain fields.

Tensile experiments on different specimen geometries were also conducted to investigate how the geometry affected the response of the specimens during loading. By
analysing the size effects and by using normalisation it was found that the behaviour
of the material during tensile experiments was independent of the geometry. Using
x-ray tomography images, a thickness increase was measured, all the way from loading
start to sample failure. It was found that right before the failure strength, the material
experienced a higher dilation compared to during the rest of the experiment. It was
further found, using digital volume correlation, that the normal strains in the loading
direction localised in parabolic zones with higher strains between the notches in the
test sample. From the shear strain fields it was also noted that in close proximity to
the failure strength, shear strains increased.

The thickness increase right before failure was probably caused by delamination of
the paperboard. However, even though delamination results in dilation of the sample
it was proven, by performing tensile tests on pre-delaminated samples, that it does
not affect the cohesive failure. This means that delamination does not cause in-plane
failure. From the analysis it was instead observed that the in-plane failure occurs at
the zones with higher strains in the loading direction.

During this Master's Thesis it was found that the combination of x-ray tomography and digital volume correlation is effective to gain more information about the
internal structure and deformation of paperboard.},
  author       = {Andersson, Daniel and Hedberg, Olof},
  keyword      = {paperboard,x-ray tomography,digital volume correlation,dvc,strain field,size effect,tensile experiment,strain rate},
  language     = {eng},
  note         = {Student Paper},
  series       = {ISRN LUTFD2/TFHF-18/5223-SE},
  title        = {In-plane fracture analysis of paperboard using x-ray tomography},
  year         = {2018},
}