Comprehensive Analysis of the Structural Evolution and Dynamic Mechanical Behavior of Ferrofluids through Coarse-Grained Molecular Dynamics and Experimental Testing

Abstract

Understanding and predicting the relationship between the dynamic structure and dynamic mechanical behavior of ferrofluids at the mesoscale presents a significant challenge. Therefore, in this study, a ferrofluid model that considered the molecular structure of the carrier liquid was constructed to perform coarse-grained molecular dynamics simulations of the mesoscale structural evolution and internal particle arrangement characteristics of ferrofluids under the influence of a magnetic field. Subsequently, oscillatory shear deformation was applied to further investigate the mechanical properties of ferrofluids under dynamic strain, as well as the deformation and disruption of their orientational structures. The simulations show that the columnar aggregation of magnetic particles imparts typical viscoelastic characteristics to the ferrofluid, and these aggregated structures gradually deform and break down as the strain amplitude increases. During dynamic oscillatory shear deformation, the enhancement of the magnetic field allows the aggregated structure of magnetic particles to exhibit better resistance to deformation, thereby improving the absorption and dissipation of mechanical energy. The dynamic mechanical properties of ferrofluids obtained from coarse-grained simulations closely align with the experimental results under moderate to high magnetic fields, allowing for a certain degree of predictive capability regarding the dynamic mechanical behavior of ferrofluids.