Paper Number
PO36 

Session
Poster Session

Title
Protorheology: Visual evidence and inference

Presentation Date and Time
October 13, 2021 (Wednesday) 6:30

Track / Room
Poster Session / Ballroom 1-2-3-4

Authors (Click on name to view author profile)

1. Hossain, Tanver (University of Illinois at Urbana-Champaign, The Department of Mechanical Science and Engineering)
2. Ewoldt, Randy H. (University of Illinois at Urbana-Champaign, Department of Mechanical Science and Engineering)

Author and Affiliation Lines (in printed abstract book)
Tanver Hossain and Randy H. Ewoldt
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801

Speaker / Presenter 
Hossain, Tanver

Keywords
rheology methods

Text of Abstract
Protorheology [1] is the first thing we all do to assess rheological properties: poke, stir, stretch, squish, scoop, drop, or simply observe flow and deformation in a natural setting. However, the link between these observations and specific rheological properties is not always clear, and rarely quantified. Yet, a wealth of insight is possible from these simple observations, including estimates of viscosity, critical stress for nonlinearity (e.g. yield stress), elastic modulus, creep compliance, relaxation time, normal stress difference, extensional viscosity, thixotropic timescales, and more. Here we survey and compare protorheology flow scenarios and some common index tests to outline (i) how to map photo and video observations to evidence of different rheological phenomena and (ii) how to quantitatively infer rheological properties (understanding limitations), from the most useful and common observations. We argue for increased use of documented visual evidence and quantitative inference alongside reported rheological properties. This approach benefits the researcher by providing insight for choosing rheometric test conditions and provides important corroborating evidence for interpreting measured rheological properties and the assessment of bad data. Additionally, we outline how these methods compose a collection of recipes for “do-it-yourself” rheometry that is useful for coursework and instruction prior to, or in the absence of, access to rheometers, with examples from the University of Illinois Urbana Champaign during the Spring Semester of 2020.

[1] We could call this many things. We choose the term protorheology from proto (first in time) which evokes related usage in the terms prototype and protohuman. These are things not fully formed, and with limitations, but from which much can be learned.