On the use of stress growth data to determine strain-dependent material functions for factorable K-BKZ equations

D. C. Venerus, S. A. Tariq, B. Bernstein

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10 Scopus citations

Abstract

The procedure of using experimental stress growth data to determine strain-dependent, or damping, functions for factorable K-BKZ constitutive equations is examined. Damping functions obtained using stress growth data from simple shear and planar extensional flows in conjunction with integrated forms of factored K-BKZ models are compared with the damping function obtained from shear step-strain experiments. Results for the low-density polyethylene (LDPE) known as IUPAC X are presented that demonstrate the difficulties encountered with this method, which can be quite serious for planar extensional flow. These results appear to be consistent with previous studies on several polymer melts where uniaxial extension stress growth data were used to determine damping functions. This body of evidence raises important questions about the use of this procedure and the strain-dependent and, apparently, test-dependent functions that are obtained. An explanation for these results is proposed which suggests that these observations may be due to an intrinsic shortcoming of K-BKZ theories.

Original languageEnglish (US)
Pages (from-to)299-315
Number of pages17
JournalJournal of Non-Newtonian Fluid Mechanics
Volume49
Issue number2-3
DOIs
StatePublished - Oct 1993
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering
  • Applied Mathematics

Keywords

  • K-BKZ models
  • constitutive equations
  • damping
  • low-density polyethylene
  • stress growth data

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