Yielding in colloidal gels: From local structure to mesoscale strand breakage and macroscopic failure

We report numerical simulations of creep flow and yielding of particulate depletion gels under constant shear stress, combining data on different length and time scales. We characterize the statistics of mesoscale strand-breaking events in the gel, which are distributed homogeneously in space, corresponding to macroscopically ductile flow. At the microscale, a spatiotemporal analysis of structural and mechanical metrics connects properties of strands before and after they fail, indicating that strand breakage is statistically predictable. Using results from different scales, we discuss the interplay between creeping and aging dynamics, and we demonstrate a viscosity bifurcation.