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Surface topography measurements of thin aluminium foil transferred to FE-simulations

Larsson, Filip LU (2016) MMTM01 20161
Production and Materials Engineering
Abstract
This work is a master thesis preformed by Filip Larsson. The objectives are to measure the aluminium foil used in packaging industry by Tetra Pak. By measuring the surface topography on both sides, the thickness variation will be determined. The measurement results shall then be used in FEM simulations.
The Alicona InfiniteFocus microscope at LTH was chosen to perform the measurements. It is a microscope based on the focus variation technique. The measurements were divided into two rounds; the first round contained measurements on one surface of the aluminium foil while the second round contained rotational measurements.
Several comparisons were made during the work of this thesis. The first comparison was investigating the difference... (More)
This work is a master thesis preformed by Filip Larsson. The objectives are to measure the aluminium foil used in packaging industry by Tetra Pak. By measuring the surface topography on both sides, the thickness variation will be determined. The measurement results shall then be used in FEM simulations.
The Alicona InfiniteFocus microscope at LTH was chosen to perform the measurements. It is a microscope based on the focus variation technique. The measurements were divided into two rounds; the first round contained measurements on one surface of the aluminium foil while the second round contained rotational measurements.
Several comparisons were made during the work of this thesis. The first comparison was investigating the difference between the two sides of the aluminium foil. This comparison showed that the matt side is coarser then the bright side of the foil. The Sa parameter is 50 % higher for the matt side. The bright side has a clear feature of rolling lines. The rolling lines shows up as clear directions in the gradient images. Surprisingly does the matt side have a main direction as well visible in its gradient image. The direction of the matt side is perpendicular to the direction of the rolling lines on the bright side.
The rotational measurements were never successful so therefore was no true thickness variation achieved. Into the simulation models were two one sided measurements used. The models had a size of 100x100 µm and were set up so they would resemble a little piece of a large tensile test. Three models were used for simulations; they were subjected to tension loading in machine direction (MD), 45 degree direction (45°) and cross direction (CD).
When the correct conditions for the models were achieved all models showed clear localized necks. The strain values were all along the neck well over a 100 % and the maximum was well over 200 %. The neck of the MD model looks like it is following the surface topography of the matt side. The necks in 45° and CD models were probably due to slip band formations and not the topography.
The measurements and their results might not be that reliable. At a maximum were five measurements done on one side, in some case only one per side. This means that the statistical significance is low for the measurement results. That no rotational measurements were successful was due to the hard light conditions. The foil is very reflective and the microscope could not handle the big differences in light during a measurement. During this thesis was a workflow developed that transferred experimental surface topography measurements into a FE-mesh. (Less)
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author
Larsson, Filip LU
supervisor
organization
course
MMTM01 20161
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8883739
date added to LUP
2016-06-21 13:22:50
date last changed
2016-06-21 13:22:50
@misc{8883739,
  abstract     = {This work is a master thesis preformed by Filip Larsson. The objectives are to measure the aluminium foil used in packaging industry by Tetra Pak. By measuring the surface topography on both sides, the thickness variation will be determined. The measurement results shall then be used in FEM simulations.
The Alicona InfiniteFocus microscope at LTH was chosen to perform the measurements. It is a microscope based on the focus variation technique. The measurements were divided into two rounds; the first round contained measurements on one surface of the aluminium foil while the second round contained rotational measurements.
Several comparisons were made during the work of this thesis. The first comparison was investigating the difference between the two sides of the aluminium foil. This comparison showed that the matt side is coarser then the bright side of the foil. The Sa parameter is 50 % higher for the matt side. The bright side has a clear feature of rolling lines. The rolling lines shows up as clear directions in the gradient images. Surprisingly does the matt side have a main direction as well visible in its gradient image. The direction of the matt side is perpendicular to the direction of the rolling lines on the bright side. 
The rotational measurements were never successful so therefore was no true thickness variation achieved. Into the simulation models were two one sided measurements used. The models had a size of 100x100 µm and were set up so they would resemble a little piece of a large tensile test. Three models were used for simulations; they were subjected to tension loading in machine direction (MD), 45 degree direction (45°) and cross direction (CD). 
When the correct conditions for the models were achieved all models showed clear localized necks. The strain values were all along the neck well over a 100 % and the maximum was well over 200 %. The neck of the MD model looks like it is following the surface topography of the matt side. The necks in 45° and CD models were probably due to slip band formations and not the topography. 
The measurements and their results might not be that reliable. At a maximum were five measurements done on one side, in some case only one per side. This means that the statistical significance is low for the measurement results. That no rotational measurements were successful was due to the hard light conditions. The foil is very reflective and the microscope could not handle the big differences in light during a measurement. During this thesis was a workflow developed that transferred experimental surface topography measurements into a FE-mesh.},
  author       = {Larsson, Filip},
  language     = {eng},
  note         = {Student Paper},
  title        = {Surface topography measurements of thin aluminium foil transferred to FE-simulations},
  year         = {2016},
}