Mechanical behaviour of wet wood in sequences of compression and combined compression and shear
2006 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, Vol. 21, no 2, 231-236 p.Article in journal (Refereed) Published
During the refining of mechanical pulp, a process occurring at high speed at temperatures of 140-160°C, the flexibility and bonding ability of the wood fibres increase. To understand the mechanical behaviour of the fibres in this operation, the deformation at low speed of wet wood specimens at 50°C and 90°C were studied under different combinations of shear and compression loading using a modification of the Arcan device. The deformation in earlywood was studied using an image analysis procedure together with measurements of the work done under different loading conditions. The deformation under combined shear and compression load was different from that in pure compression. In the first cycle under compression, the fibre cell walls were bent in a characteristic "S" shape, whereas under the combined load the cells deformed according to a "brick" shape. After a first cycle under combined load, the cells deformed according to the "brick" shape even when subjected to a second load under pure compression. The first deformation cycle required the largest amount of work. Since less energy was needed for the first cycle under a combined load than under a compression load, the application of a combined load as a first cycle may be a way to permanently deform fibres using less work.
Place, publisher, year, edition, pages
2006. Vol. 21, no 2, 231-236 p.
wood, shear, compression, deformation, picea abies, energy consumption
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:kth:diva-6262DOI: 10.3183/NPPRJ-2006-21-02-p231-236ISI: 000238726200011OAI: oai:DiVA.org:kth-6262DiVA: diva2:10929
QC 20101005. Uppdaterad från submitted till published (20101005).2005-10-142005-10-142010-10-05Bibliographically approved