Microstructure Simulation and Constitutive Modelling of Magnetorheological Fluids Based on the Hexagonal Close-packed...

Area of Science:

• Materials Science
• Fluid Dynamics
• Rheology

Background:

• Magnetorheological fluids (MRFs) exhibit significant changes in viscosity under magnetic fields.
• Existing models often simplify particle structures, limiting accuracy for high particle concentrations.

Purpose of the Study:

• To develop a novel constitutive model for highly concentrated MRFs based on hexagonal close-packed particle structures.
• To accurately predict the field-dependent shear yield stress of MRFs.

Main Methods:

• Particle dynamic simulations to analyze carbonyl iron powder (CIP) particle chain formation.
• Formulation of a constitutive model utilizing hexagonal close-packed structure analysis.
• Experimental validation considering magnetic induction intensity, particle volume fraction, radius, and surfactant coating thickness.

Main Results:

• The proposed hexagonal close-packed model shows superior prediction accuracy for field-dependent shear yield stress compared to the single-chain model.
• Shear yield stress increases with higher particle volume fraction and decreased surfactant coating thickness.
• The model effectively captures the influence of particle microstructure on MRF behavior.

Conclusions:

• The developed constitutive model provides a more accurate representation of MRF behavior at high particle concentrations.
• This model can be effectively utilized for estimating the field-dependent shear yield stress in iron particle-based MRFs.
• Understanding particle chain formation and microstructure is crucial for MRF performance prediction.