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Title: Osmotic instability in soft materials under well-controlled triaxial stress
Living tissues and some engineering materials contain water. When a wet material loses water, high triaxial tensile stress may build up and cause instability. The mechanism of instability under triaxial tension has attracted great attention, but quantitative study remains an ongoing chal- lenge. Here we develop an experimental method to apply well-controlled triaxial tensile stress and observe osmotic instability in situ. We synthesize a hydrogel in an elastomer tube with strong adhesion between them. The elastomer dissolves minute amount of water, but allows water to diffuse out and places the hydrogel under homogeneous, equal-triaxial, tensile stress. We develop a method to determine the stress as a function of time. The transparent setup enables observation of various types of osmotic instabilities, including cavity nucleation, crack propagation, and surface undulation. Notably, our method enables the measurement of crack speed from ~10−5 m/ s to a limit comparable to the Rayleigh wave speed ~1 m/s. We observe a large jump in crack speed at a critical energy release rate. This work opens opportunities to study the physics of soft materials under high triaxial tension.  more » « less
Award ID(s):
2011754
PAR ID:
10501545
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Elsevier
Date Published:
Journal Name:
Journal of the Mechanics and Physics of Solids
Volume:
172
Issue:
C
ISSN:
0022-5096
Page Range / eLocation ID:
105195
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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