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Challenges in Rheological Characterization of Highly Concentrated Suspensions — A Case Study for Screen-printing Silver Pastes
Published on: April 10, 2017
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Foam rheology at large deformation
J-C Géminard1, J C Pastenes2, F Melo2
1Université Lyon, Ens de Lyon, Université Claude Bernard, CNRS, Laboratoire de Physique, Lyon F-69342, France.
Physical Review. E
|May 16, 2018
Summary
This study reveals that aqueous foams exhibit stress hardening due to plastic deformation, even at small strains. Foam remodeling under large shear stress leads to a critical yield stress, accurately modeled by a simple plastic deformation law.
Area of Science:
- Materials Science
- Rheology
- Soft Matter Physics
Background:
- Large deformations can irreversibly alter material structures, causing hardening or softening.
- Aqueous foam is a metastable, disordered system of packed gas bubbles.
Purpose of the Study:
- To investigate the mechanical response of aqueous foam under large-amplitude, quasistatic periodic shear.
- To understand the relationship between shear stress, deformation, and foam remodeling.
Main Methods:
- Subjecting a foam layer to quasistatic periodic shear at large amplitudes.
- Analyzing shear stress response as a function of applied shear.
- Developing a mathematical model to describe foam mechanical behavior.
Main Results:
- Shear stress follows a universal, near-exponential curve with increasing shear.
- An asymptotic stress value was identified as the critical yield stress for foam remodeling.
- A simple law accurately models foam mechanical response, accounting for plastic deformation.
Conclusions:
- Plastic deformation is a key factor in stress hardening in aqueous foams.
- Foam remodeling occurs at a critical yield stress, indicating significant structural changes.
- The developed model provides a clear interpretation of foam mechanical behavior under shear.
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