Prof. Sebastien Manneville (ENS de Lyon)
Failure of a protein gel under creep
Biomaterials such as protein or polysaccharide gels are known to behave
qualitatively as soft solids and to rupture under an external load. In this
seminar, I will use a combination of optical and ultrasonic imaging and shear
rheology to show that the behaviour of a protein gel under creep is strongly
reminiscent of brittle failure: after a power-law creep regime, fractures
nucleate and grow logarithmically perpendicularly to shear up to sudden rupture.
A single equation describing the temporal evolution of the strain rate during
those two successive processes nicely captures the full rheological response.
The failure time follows a robust decreasing power-law with the applied shear
stress, which is known as the Basquin law in the literature of solids. Our
results are in excellent agreement with recent fiber-bundle models that include
damage accumulation on elastic fibers and exemplify protein gels as model
brittle-like soft solids. Finally I will discuss the influence of the gel
composition and microstructure in light of recent models for materials with