Microscopic rupture precursors in protein gels under fatigue – MICROFAT

We aim at understanding the microscopic physical mechanisms that cause colloidal gels to break under fatigue, i.e., under an oscillatory stress. We will study protein gels that consist of a three-dimensional network of entangled strands. These gels are of particular importance in the food industry. From a fundamental point of view, they present a brittle-like rupture involving plasticity and fractures. We will experimentally formulate gels whose strand network topology can be adjusted by playing on the interactions. We will determine the influence of this microstructure on the microscopic precursors of fracture by combining rheometry and confocal microscopy, both in shear and compression. Numerical simulations will provide access to the full dynamics, from the scale of the individual particle to that of the network, therefore allowing us to distinguish universal features in order to propose a predictive physical framework for fatigue-induced failure.