Mao Runsong, Wang Huixing, Zhang Guang, Ye Xudan, Wang Jiong
School of Mechanical Engineering, Nanjing University of Science and Technology Nanjing 210094 China
RSC Adv. 2020 Aug 27;10(53):31691-31704. doi: 10.1039/d0ra05843b. eCollection 2020 Aug 26.
Magnetorheological gel (MRG) is a kind of magneto-sensitive smart material mainly composed of soft magnetic particles and polyurethane, which can decrease or even avoid the severe sedimentation problem appearing in MR fluids. In this work, the rheological properties of MRG under quasi-statically monotonic and cyclic loading with large deformation were investigated, respectively. The results could provide effective guidance for the design of MR devices that are often subjected to quasi-static loading. Firstly, MRG was fabricated by mixing carbonyl iron particles (CIPs) with the polyurethane matrix. Then, variations of normal force with time and magnetic field for MRG were tested and discussed. Moreover, the influences of CIPs content, shear rate, shear strain amplitude and magnetic field on the energy dissipation density of MRG were analyzed. The results showed the magneto-induced damping performance of MRG is highly relevant to the CIPs content and magnetic field, the magneto-induced enhancement of energy dissipation density of MRG with 60% CIPs content could reach up to 104 900% when the external magnetic strength increases to 391 kA m. Furthermore, the related mechanisms, from the perspective of microstructure, were proposed to qualitatively explain the various mechanical phenomena occurring in shear stress and normal force.
磁流变凝胶(MRG)是一种主要由软磁颗粒和聚氨酯组成的磁敏智能材料,它可以减少甚至避免磁流变液中出现的严重沉降问题。在这项工作中,分别研究了MRG在大变形准静态单调加载和循环加载下的流变特性。研究结果可为经常承受准静态载荷的磁流变装置的设计提供有效指导。首先,通过将羰基铁颗粒(CIPs)与聚氨酯基体混合制备了MRG。然后,测试并讨论了MRG的法向力随时间和磁场的变化。此外,分析了CIPs含量、剪切速率、剪切应变幅值和磁场对MRG能量耗散密度的影响。结果表明,MRG的磁致阻尼性能与CIPs含量和磁场高度相关,当外部磁场强度增加到391 kA/m时,CIPs含量为60%的MRG的磁致能量耗散密度增强可达104900%。此外,从微观结构的角度提出了相关机制,以定性解释剪切应力和法向力中出现的各种力学现象。