Modeling of paste extrusion in semi-solid state

Mitsoulis, E; Zisis, T; Hatzikiriakos, SG

dc.contributor.author	Mitsoulis, E	en
dc.contributor.author	Zisis, T	en
dc.contributor.author	Hatzikiriakos, SG	en
dc.date.accessioned	2014-03-01T01:28:47Z
dc.date.available	2014-03-01T01:28:47Z
dc.date.issued	2008	en
dc.identifier.issn	19606206	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/18969
dc.subject	Die design	en
dc.subject	Numerical simulation	en
dc.subject	PTFE paste extrusion	en
dc.subject	Semi-solid modeling	en
dc.subject	Structure parameter	en
dc.subject.other	Constitutive relations	en
dc.subject.other	Die design	en
dc.subject.other	Extrusion pressure	en
dc.subject.other	Fibril formation	en
dc.subject.other	Finite element simulations	en
dc.subject.other	First order kinetics	en
dc.subject.other	Flow type	en
dc.subject.other	Geometrical parameters	en
dc.subject.other	Microscopic models	en
dc.subject.other	Mixed type	en
dc.subject.other	Numerical simulation	en
dc.subject.other	Relative contribution	en
dc.subject.other	Relative strength	en
dc.subject.other	Rheological equations	en
dc.subject.other	Semi-solid state	en
dc.subject.other	Semi-solids	en
dc.subject.other	Shear rates	en
dc.subject.other	Shear thickening	en
dc.subject.other	Shear thinning	en
dc.subject.other	Structural parameter	en
dc.subject.other	Computer simulation	en
dc.subject.other	Dies	en
dc.subject.other	Differential equations	en
dc.subject.other	Extrusion	en
dc.subject.other	Shear deformation	en
dc.subject.other	Strain rate	en
dc.subject.other	Structural design	en
dc.title	Modeling of paste extrusion in semi-solid state	en
heal.type	journalArticle	en
heal.identifier.primary	10.1007/s12289-008-0289-4	en
heal.identifier.secondary	http://dx.doi.org/10.1007/s12289-008-0289-4	en
heal.publicationDate	2008	en
heal.abstract	A constitutive rheological equation is proposed for the paste extrusion of polytetrafluoroethylene (PTFE) that takes into account the continuous change of the microstructure during flow, through fibril formation. The mechanism of fibrillation is captured through a microscopic model for a structural parameter, ξ. This model essentially represents a balance of fibrillated and unfibrillated domains in the PTFE paste through a first-order kinetic differential equation. The rate of fibril formation is assumed to be a function of the strain rate and a flow type parameter, which describes the relative strength of straining and rotation in mixed type flows. The proposed constitutive equation consists of shear-thinning and shear-thickening terms, the relative contribution of the two being a function of ξ. Finite element simulations using the proposed constitutive relation predict correctly the variations of the extrusion pressure with the apparent shear rate and die geometrical parameters. © Springer/ESAFORM 2008.	en
heal.journalName	International Journal of Material Forming	en
dc.identifier.doi	10.1007/s12289-008-0289-4	en
dc.identifier.volume	1	en
dc.identifier.issue	SUPPL. 1	en
dc.identifier.spage	771	en
dc.identifier.epage	774	en