Determination of local strains and breaking behaviour of wet paper using a high-speed camera

Timo Lappalainen (Corresponding Author), Jarmo Kouko

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)

Abstract

In this study, the digital image correlation (DIC) method was used to determine local strains in paper strips during a tensile test. The grammage of never-dried LWC paper from the pilot paper machine was 38 g/m2 and the dryness ranged from 50 to 75%. The maximal straining speed in the single-phase tensile test was 100 mm/s and the corresponding image acquisition rate was 9000 frames/s. The local maximal strain εMAX in every paper strip that was analyzed was larger than the strain at the break value εBreak of the strip, as determined from the tension-strain curve. The largest εMAX to εBreak ratio was about 1.7. It was possible to estimate the starting region of the fracture based on the measured local strains. In the single-phase tensile test, the fracture started lengthways along the strip from the zone with the largest local difference between the strains on the left and right edges of the paper strip. At that zone the fracture usually started from the edge of the strip where the local strain was larger. In the three-phase tensile test, the fracture started lengthways along the strip from the zone with the largest local strain. In this case, the fracture usually also started from the edge of the strip with more local strain of the two. The relaxation phase seemed to have a significant effect on the breaking behavior of the wet paper strip.
Original languageEnglish
Pages (from-to)288-296
Number of pages9
JournalNordic Pulp and Paper Research Journal
Volume26
Issue number3
DOIs
Publication statusPublished - 2011
MoE publication typeA1 Journal article-refereed

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High speed cameras
cameras
digital image
testing
speed
paper
Correlation methods
Image acquisition
digital images
test

Keywords

  • local deformations
  • tensile test
  • fracture
  • high-speed camera
  • wet paper
  • LWC

Cite this

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title = "Determination of local strains and breaking behaviour of wet paper using a high-speed camera",
abstract = "In this study, the digital image correlation (DIC) method was used to determine local strains in paper strips during a tensile test. The grammage of never-dried LWC paper from the pilot paper machine was 38 g/m2 and the dryness ranged from 50 to 75{\%}. The maximal straining speed in the single-phase tensile test was 100 mm/s and the corresponding image acquisition rate was 9000 frames/s. The local maximal strain εMAX in every paper strip that was analyzed was larger than the strain at the break value εBreak of the strip, as determined from the tension-strain curve. The largest εMAX to εBreak ratio was about 1.7. It was possible to estimate the starting region of the fracture based on the measured local strains. In the single-phase tensile test, the fracture started lengthways along the strip from the zone with the largest local difference between the strains on the left and right edges of the paper strip. At that zone the fracture usually started from the edge of the strip where the local strain was larger. In the three-phase tensile test, the fracture started lengthways along the strip from the zone with the largest local strain. In this case, the fracture usually also started from the edge of the strip with more local strain of the two. The relaxation phase seemed to have a significant effect on the breaking behavior of the wet paper strip.",
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Determination of local strains and breaking behaviour of wet paper using a high-speed camera. / Lappalainen, Timo (Corresponding Author); Kouko, Jarmo.

In: Nordic Pulp and Paper Research Journal, Vol. 26, No. 3, 2011, p. 288-296.

Research output: Contribution to journalArticleScientificpeer-review

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AB - In this study, the digital image correlation (DIC) method was used to determine local strains in paper strips during a tensile test. The grammage of never-dried LWC paper from the pilot paper machine was 38 g/m2 and the dryness ranged from 50 to 75%. The maximal straining speed in the single-phase tensile test was 100 mm/s and the corresponding image acquisition rate was 9000 frames/s. The local maximal strain εMAX in every paper strip that was analyzed was larger than the strain at the break value εBreak of the strip, as determined from the tension-strain curve. The largest εMAX to εBreak ratio was about 1.7. It was possible to estimate the starting region of the fracture based on the measured local strains. In the single-phase tensile test, the fracture started lengthways along the strip from the zone with the largest local difference between the strains on the left and right edges of the paper strip. At that zone the fracture usually started from the edge of the strip where the local strain was larger. In the three-phase tensile test, the fracture started lengthways along the strip from the zone with the largest local strain. In this case, the fracture usually also started from the edge of the strip with more local strain of the two. The relaxation phase seemed to have a significant effect on the breaking behavior of the wet paper strip.

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