Transition between solid and liquid state of yield-stress fluids under purely extensional deformations

Stylianos Varchanis, Simon J. Haward, Cameron C. Hopkins, Alexandros Syrakos, Amy Q. Shen, Yannis Dimakopoulos, John Tsamopoulos

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


We report experimental microfluidic measurements and theoretical modeling of elastoviscoplastic materials under steady, planar elongation. Employing a theory that allows the solid state to deform, we predict the yielding and flow dynamics of such complex materials in pure extensional flows. We find a significant deviation of the ratio of the elongational to the shear yield stress from the standard value predicted by ideal viscoplastic theory, which is attributed to the normal stresses that develop in the solid state prior to yielding. Our results show that the yield strain of the material governs the transition dynamics from the solid state to the liquid state. Finally, given the difficulties of quantifying the stress field in such materials under elongational flow conditions, we identify a simple scaling law that enables the determination of the elongational yield stress from experimentally measured velocity fields.

Original languageEnglish (US)
Pages (from-to)12611-12617
Number of pages7
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number23
StatePublished - Jun 9 2020


  • Elastoviscoplastic materials
  • Extensional flow
  • Viscoplastic materials
  • Yield strain
  • Yield stress

ASJC Scopus subject areas

  • General


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