Understanding rheological hysteresis in soft glassy materials

Area of Science:

• Soft Matter Physics
• Rheology
• Materials Science

Background:

• Recent experiments show rheological hysteresis in soft glassy materials.
• Understanding this hysteresis is crucial for material characterization and application.

Purpose of the Study:

• To numerically investigate strain rate sweeps in simple and viscosity bifurcating yield stress fluids.
• To explain the experimentally observed differences in rheological hysteresis loop area dependence on sweep time.

Main Methods:

• Numerical simulations using fluidity models and the soft glassy rheology model.
• Performing downward followed by upward strain rate sweeps.
• Analyzing the area of the rheological hysteresis loop.

Main Results:

• Simulations successfully capture the monotonic decrease of hysteresis loop area with sweep time in simple yield stress fluids.
• Simulations reproduce the bell-shaped dependence of hysteresis loop area on sweep time in viscosity bifurcating fluids.
• Identified shear banding as a key factor explaining the different hysteresis behaviors.

Conclusions:

• The study provides a numerical explanation for distinct rheological hysteresis behaviors in different types of yield stress fluids.
• Simulation results align with experimental observations across four soft glassy materials.
• Differences in shear banding tendencies explain the observed hysteresis loop area dependencies.