Intertwined and demixed double networks: architecture, rheology, and toughness

Soft jammed materials can resist deformation or accommodate steady flow depending on imposed stresses and deformation rates. We have studied the yielding and the stress relaxationduring shear start-up in this broad range of materials using microscopic simulations of model jammed suspensions. Through an extensive analysis of microscopic stresses, displacements, and packing morphology, we have characterized timescales and length scales that control the stress relaxation, depending also on varying sample preparation. We have quantified stress anisotropy, connected the microscopic rearrangement underpinning the relaxation to the non-affine displacements under deformation, and studied the evolution of the packing through a time-resolved Voronoi analysis. The stress relaxation analysis allows us to disentangle the role of elasticity and plasticity in the pre-yielding regime leading to both ductile and brittle yielding associated to shear banding, and in the recovering of rigidity and mechanical stability after flow cessation.