Pei Pei, Peng Yongbo
State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, P. R. China.
Soft Matter. 2021 Jan 7;17(1):184-200. doi: 10.1039/d0sm01149e. Epub 2020 Nov 9.
Systematic molecular dynamics simulations are conducted on magnetorheological (MR) fluids under steady state, squeeze flows and shear flows. The present study concerns the squeeze-assisted MR fluid strengthening and correlates the suspensions' macroscopic rheological properties to their microstructure evolution in terms of the aggregation kinetics. Simulation results demonstrate that the squeeze strengthening effect on the rheological properties of MR fluids is enhanced with the increasing magnetic field and becomes more prominent for dilute suspensions, but weakened with the increasing squeeze rate after the critical squeeze rate is surpassed. By microscopic inspection, it is found that the rheological properties of MR fluids under squeeze flows are consistent with the microstructured behaviors of MR suspensions in terms of the particle distribution, cluster kinetics, particle connectivity and magnetic energy. This study provides a microstructural insight into the squeeze-assisted MR fluid strengthening, which helps to attain an elegant design of MR devices with high shear performance requirements.
在稳态、挤压流动和剪切流动条件下，对磁流变（MR）流体进行了系统的分子动力学模拟。本研究关注挤压辅助的磁流变流体强化，并根据聚集动力学将悬浮液的宏观流变特性与其微观结构演变相关联。模拟结果表明，随着磁场强度的增加，挤压对磁流变流体流变特性的强化作用增强，且对于稀悬浮液更为显著，但在超过临界挤压速率后，随着挤压速率的增加而减弱。通过微观观察发现，在挤压流动下磁流变流体的流变特性在颗粒分布、团簇动力学、颗粒连通性和磁能方面与磁流变悬浮液的微观结构行为一致。本研究为挤压辅助的磁流变流体强化提供了微观结构方面的见解，有助于实现对具有高剪切性能要求的磁流变装置的优化设计。
