Paper Number
FI21                         My Program 

Session
Flow-Induced Instabilities and Non-Newtonian Fluids

Title
A universal relationship between linear and nonlinear responses in soft materials

Presentation Date and Time
October 21, 2025 (Tuesday) 11:10

Track / Room
Track 7 / Sweeney Ballroom D

Authors (Click on name to view author profile)

  1. Poling-Skutvik, Ryan (University of Rhode Island, Chemical, Biomolecular, and Material Engineering)
  2. Keane, Daniel (University of Rhode Island, Chemical, Biomolecular, and Materials Engineering)
  3. Nikoumanesh, Elnaz (University of Rhode Island)
  4. Rogers, Simon A. (University of Illinois Urbana-Champaign, Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Ryan Poling-Skutvik1, Daniel Keane1, Elnaz Nikoumanesh1 and Simon A. Rogers2
1Chemical, Biomolecular, and Material Engineering, University of Rhode Island, Kingston, RI 02881; 2Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801

Speaker / Presenter 
Poling-Skutvik, Ryan

Keywords
experimental methods; flow-induced instabilities; networks; non-Newtonian fluids

Text of Abstract
Yielding is a phenomenon in which a material transitions from elastic deformation to viscous dissipation when subjected to large deformations. This transition has been described and studied for over a century, but it remains elusive to predict in soft materials. Instead, rheologists characterize this transition empirically using a variety of protocols, the most common of which is large amplitude oscillatory shear. During this protocol, a material subjected to a sinusoidal strain (or stress) at a constant frequency with progressively larger amplitudes and the viscoelastic moduli are quantified by the proportional response in stress (or strain). The onset of nonlinearity in this response is often characterized by a peak in the loss modulus G”, which precedes the crossover from a primarily elastic regime to a primarily viscous response. In this work, we show that the height of this peak can be fully predicted by tan(d) in the linear response. Additionally, the position of this peak is predicted by a combination of this linear viscoelasticity and flow stress. These relationships hold across material chemistry and structure and orders of magnitude in material elasticity. Our work therefore demonstrates that the same fundamental physics controlling the viscoelastic response under linear deformations is preserved across the yield transition. Furthermore, the direct relationship between the G” peak and linear material properties indicates that the G” peak is not an independent metric by which to classify the yield transition.