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Licensed Unlicensed Requires Authentication Published by De Gruyter December 3, 2008

On the energy consumption for crack development in fibre wall in disc refining – A micromechanical approach

Jan-Erik Berg, Mårten E. Gulliksson and Per A. Gradin
From the journal


An analytical model has been applied to calculate the acquired strain energy density in order to achieve a certain damage state in a softwood fibre by uniaxial tension or shear load. The energy density was found to be dependent on the microfibril angle in the middle secondary wall, the loading case, the thicknesses of the fibre cell wall layers, and conditions, such as moisture content and temperature. At conditions, prevailing at the entrance of the gap between the plates in a refiner and at relative high damage states, more energy is needed to create cracks at higher microfibril angles. The energy density was lower for earlywood compared to latewood fibres. For low microfibril angles, the energy density was lower for loading in shear compared to tension for both earlywood and latewood fibres. Material parameters, such as initial damage state and specific fracture energy, were determined by fitting of input parameters to experimental data.

Corresponding author. Fibre Science and Communication Network, Mid Sweden University, SE-851 70, Sundsvall, Sweden

Received: 2008-6-4
Accepted: 2008-10-9
Published Online: 2008-12-03
Published Online: 2008-12-03
Published in Print: 2009-03-01

©2009 by Walter de Gruyter Berlin New York

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