Abdul Kadir Khairul Anwar, Nazmi Nurhazimah, Mohamad Norzilawati, Shabdin Muhammad Kashfi, Adiputra Dimas, Mazlan Saiful Amri, Nordin Nur Azmah, Mohd Yusuf Shahir
Engineering Materials and Structures (eMast) iKohza, Malaysia-Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, Kuala Lumpur 54100, Malaysia.
Faculty of Engineering, Universiti Malaysia Sabah, Jalan UMS, Kota Kinabalu 88400, Malaysia.
Materials (Basel). 2022 Aug 19;15(16):5717. doi: 10.3390/ma15165717.
Recently, magnetorheological grease (MRG) has been utilized in magnetorheological (MR) brakes to generate a braking torque based on the current applied. However, the high initial viscosity of MRG has increased the off-state torque that led to the viscous drag of the brake. Therefore, in this study, the off-state viscosity of MRG can be reduced by the introduction of dilution oil as an additive. Three samples consist of pure MRG (MRG 1) and MRG with different types of dilution oil; hydraulic (MRG 2) and kerosene (MRG 3) were prepared by mixing grease and spherical carbonyl iron particles (CIP) using a mechanical stirrer. The rheological properties in the rotational mode were examined using a rheometer and the torque performances in MR brake were evaluated by changing the current of 0 A, 0.4 A, 0.8 A, and 1.2 A with fixed angular speed. The result shows that MRG 3 has the lowest viscosity which is almost 93% reduction while the viscosity of MRG 2 has lowered to 25%. However, the torque performances generated by MRG 3 were highest, 1.44 Nm, when 1.2 A of current was applied and followed by MRG 2 and MRG 1. This phenomenon indicated that the improvement of torque performances was dependent on the viscosity of MRG. By reducing the viscosity of MRG, the restriction on CIP to form chain formation has also decreased and strengthen the torque of MRG brake. Consequently, the utilization of dilution oil in MRG could be considered in MR brake in near future.
最近，磁流变润滑脂（MRG）已被应用于磁流变（MR）制动器中，以根据施加的电流产生制动扭矩。然而，MRG的高初始粘度增加了导致制动器粘性阻力的关态扭矩。因此，在本研究中，可以通过引入稀释油作为添加剂来降低MRG的关态粘度。通过使用机械搅拌器将润滑脂与球形羰基铁颗粒（CIP）混合，制备了三个样品，分别为纯MRG（MRG 1）和含有不同类型稀释油的MRG；液压油（MRG 2）和煤油（MRG 3）。使用流变仪检查旋转模式下的流变特性，并通过在固定角速度下改变0 A、0.4 A、0.8 A和1.2 A的电流来评估MR制动器中的扭矩性能。结果表明，MRG 3的粘度最低，几乎降低了93%，而MRG 2的粘度降低到了25%。然而，当施加1.2 A电流时，MRG 3产生的扭矩性能最高，为1.44 Nm，其次是MRG 2和MRG 1。这种现象表明，扭矩性能的提高取决于MRG的粘度。通过降低MRG的粘度，对CIP形成链状结构的限制也降低了，并增强了MRG制动器的扭矩。因此，在不久的将来，MR制动器中可以考虑在MRG中使用稀释油。
