Softening and Yielding of Soft Glassy Materials

Abstract

Solids deform and fluids flow, but soft glassy materials, such as emulsions, foams, suspensions, and pastes, exhibit an intricate mix of solid and liquid-like behavior. While much progress has been made to understand their elastic (small strain) and flow (infinite strain) properties, such understanding is lacking for the softening and yielding phenomena that connect these asymptotic regimes. Here we present a comprehensive framework for softening and yielding of soft glassy materials, based on extensive numerical simulations of oscillatory rheological tests, and show that two distinct scenarios unfold depending on the material's packing density. For dense systems, there is a single, pressure-independent strain where the elastic modulus drops and the particle motion becomes diffusive. In contrast, for weakly jammed systems, a two-step process arises: at an intermediate softening strain, the elastic and loss moduli both drop down and then reach a new plateau value, whereas the particle motion becomes diffusive at the distinctly larger yield strain. We show that softening is associated with an extensive number of microscopic contact changes leading to a non-analytic rheological signature. Moreover, the scaling of the softening strain with pressure suggest the existence of a novel pressure scale above which softening and yielding coincide, and we verify the existence of this crossover scale numerically. Our findings thus evidence the existence of two distinct classes of soft glassy materials -- jamming dominated and dense -- and show how these can be distinguished by their rheological fingerprint.

9 pages, 11 figures, to appear in Soft Matter

References in corpus (10)

• Jamming at Zero Temperature and Zero Applied Stress: the Epitome of Disorder
• The Jamming Transition in Granular Systems
• Strain-Rate Frequency Superposition (SRFS) - A rheological probe of structural relaxation in soft materials
• Critical scaling in linear response of frictionless granular packings near jamming
• Microfluidic rheology of soft colloids above and below jamming
• A microscopic view of the yielding transition in concentrated emulsions
• Soft Sphere Packings at Finite Pressure but Unstable to Shear
• Jamming in finite systems: stability, anisotropy, fluctuations and scaling
• Contact Changes near Jamming
• Nonlocal elasticity near jamming

Cited by in corpus (25)

• Sticky Matter: Jamming and rigid cluster statistics with attractive particle interactions
• The effect of cryogenic thermal cycling on aging, rejuvenation, and mechanical properties of metallic glasses
• Unified phase diagram of reversible-irreversible, jamming and yielding transitions in cyclically sheared soft sphere packings
• Classification of the reversible-irreversible transitions in particle trajectories across the jamming transition point
• The yielding transition in periodically sheared binary glasses at finite temperature
• Slow relaxation dynamics in binary glasses during stress-controlled, tension-compression cyclic loading
• Accelerated relaxation in disordered solids under cyclic loading with alternating shear orientation
• Soft grain compression: beyond the jamming point
• Elasticity of Jammed Packings of Sticky Disks
• Normal stresses, contraction, and stiffening in sheared elastic networks
• Structural relaxation in amorphous materials under cyclic tension-compression loading
• Scaling laws for frictional granular materials confined by constant pressure under oscillatory shear
• Softening and residual loss modulus of jammed grains under oscillatory shear in an absorbing state
• The influence of periodic shear on structural relaxation and pore redistribution in binary glasses
• Strain-controlled critical slowing down in the rheology of disordered networks
• Structural transformations during periodic deformation of low-porosity amorphous materials
• Eigenvalue analysis of stress-strain curve of two-dimensional amorphous solids of dispersed frictional grains with finite shear strain
• Shear modulus and reversible particle trajectories of frictional granular materials under oscillatory shear
• Structural relaxation and delayed yielding in cyclically sheared Cu-Zr metallic glasses
• Geometrical properties of mechanically annealed systems near the jamming transition
• Self-induced buckling in hollow microgels
• Rigidity transition of a highly compressible granular medium
• Theory of rigidity and numerical analysis of density of states of two-dimensional amorphous solids with dispersed frictional grains in the linear response regime
• An exact expression of three-body system for the complex shear modulus of frictional granular materials
• Dilatancy of frictional granular materials under oscillatory shear with constant pressure