Influence of gravity on curl of horizontal paper sheets
2001 (English)In: TAPPI Journal, ISSN 0734-1415, Vol. 84, no 5, 73-73 p.Article in journal (Refereed) Published
The influence of gravity on the out-of-plane hygroinstability (curl) of horizontal paper sheets was studied analytically and experimentally. Nondimensional parameters describing the relative importance of moisture and gravity on paper deflections are defined. An approximative analysis based on cylindrical bending allows prediction of contact length, taking into account moisture and gravity. Linear and geometrically nonlinear finite-element analyses were performed on sheets resting on a flat horizontal surface. The contact problem was solved using an algorithm incorporated in the finite-element code. Gravity reduced the deflections and flattened the sheet over a contact region that decreases with increasing basis weight. The results indicate that the influence of gravity should be considered when evaluating the curl for horizontal papers of basis weight below 120 g/m2(superscript) and size equal to or larger than A4 (210 mm × 297 mm). Two-ply laboratory sheets of 60- and 100-g/m2(superscript) basis weight were manufactured from bleached chemical pulp. Vertical deflections were measured on horizontal sheets measuring 17 cm × 23 cm. It was found that gravity substantially reduced the deflections and that the sheets flattened in a central contact region. The predicted and experimentally observed deflections agreed within (Plus over Minus)1 mm.
Place, publisher, year, edition, pages
2001. Vol. 84, no 5, 73-73 p.
IdentifiersURN: urn:nbn:se:kth:diva-20625ISI: 000168662900022OAI: oai:DiVA.org:kth-20625DiVA: diva2:339321
QC 201005252010-08-102010-08-102010-10-22Bibliographically approved