Some issues arising in finding the detachment point in calendering of plastic sheets

Mitsoulis, E

dc.contributor.author	Mitsoulis, E	en
dc.date.accessioned	2014-03-01T01:34:37Z
dc.date.available	2014-03-01T01:34:37Z
dc.date.issued	2010	en
dc.identifier.issn	8756-0879	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/20778
dc.subject	calendering	en
dc.subject	detachment point	en
dc.subject	finite elements	en
dc.subject	free surfaces.	en
dc.subject	power-law model	en
dc.subject	sheet thickness	en
dc.subject.classification	Materials Science, Coatings & Films	en
dc.subject.other	detachment point	en
dc.subject.other	Finite Element	en
dc.subject.other	Free surfaces	en
dc.subject.other	Power law model	en
dc.subject.other	Sheet thickness	en
dc.subject.other	Approximation theory	en
dc.subject.other	Boundary element method	en
dc.subject.other	Calendering	en
dc.subject.other	Calenders	en
dc.subject.other	Contact angle	en
dc.subject.other	Crystallography	en
dc.subject.other	Indexing (of information)	en
dc.subject.other	Plastic sheets	en
dc.subject.other	Polymer melts	en
dc.subject.other	Surfaces	en
dc.subject.other	Traction (friction)	en
dc.subject.other	Two dimensional	en
dc.subject.other	Finite element method	en
dc.title	Some issues arising in finding the detachment point in calendering of plastic sheets	en
heal.type	journalArticle	en
heal.identifier.primary	10.1177/8756087910376144	en
heal.identifier.secondary	http://dx.doi.org/10.1177/8756087910376144	en
heal.language	English	en
heal.publicationDate	2010	en
heal.abstract	Calendering is a process for producing plastic sheets of a desired final thickness and appearance. The thickness of the exiting sheet during a calendering operation is uniquely found by the lubrication approximation theory and the application of the Swift boundary conditions, which dictate that both the pressure and its axial derivative are zero at detachment. This cannot be used in a 2D analysis of the process, where the detachment point is the anchor of a free surface, and hence a singular point where both the pressure and the stresses go through numerical oscillations. This difficulty can be circumvented by using the boundary element method (BEM), which uses as primary variables velocities and tractions, and thus avoids pressures and stresses. Then the detachment point is found as the point where the tangential traction becomes zero. Numerical tests undertaken here with the finite element method (FEM) show that the LAT results can be used as a good approximation for the detachment point, which is then fixed. Comparisons with 2D BEM results show a good agreement for all flow field variables. However, the exact position of the detachment point in a 2D FEM analysis is still elusive, since for viscous polymer melts the contact angle is not known and should be part of the solution. Some thoughts are given about how to tackle this still unresolved issue, based on double nodes with discontinuous velocities and pressures. © The Author(s), 2010.	en
heal.publisher	SAGE PUBLICATIONS LTD	en
heal.journalName	Journal of Plastic Film and Sheeting	en
dc.identifier.doi	10.1177/8756087910376144	en
dc.identifier.isi	ISI:000281316600002	en
dc.identifier.volume	26	en
dc.identifier.issue	2	en
dc.identifier.spage	141	en
dc.identifier.epage	165	en