Determining the critical strain in the fracture process zone by different methods

Rolf Wathén, Bo Westerlind, Warren Batchelor, Kaarlo Niskanen

Research output: Contribution to conferencePaper

2 Citations (Scopus)


This study considers the straining mechanisms of paper and board during the fracture process. On an intuitive level, it is easy to accept that many fracture problems would be avoided if the paper material would tolerate large levels of local strain in the areas where the applied deformations are largest. There is evidence indicating that paper materials can tolerate much higher local strains than what is measured in the ordinary tensile test. We determined the local strain levels of paper. The results show that ordinary breaking strain generally does not correlate with, and is much smaller than, the "post-fracture" strain that develops inside the fracture process zone (FPZ). In particular, no improvement in the FPZ strain arises from drying shrinkage. Significant improvements in the FPZ strain require much larger effects, e.g. such that can arise if fibres are turned and pulled parallel to loading during the fracture process. This fibre straightening contribution should be large if fibre curl and other distortions from straight shape are large or if the fibres in the paper are flexible.

Original languageEnglish
Number of pages7
Publication statusPublished - 20 Nov 2003
EventInternational Paper Physics Conference 2003 - Victoria, BC, Canada
Duration: 7 Sep 200311 Sep 2003


ConferenceInternational Paper Physics Conference 2003
Abbreviated titlePAPTAC 2003
CityVictoria, BC
Internet address

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