Study of the Effect of Continuous Thermal Effects on the Shear Stability of Magnetorheological Grease

Abstract

Magnetorheological dampers in the service of the medium in a project experience continuous thermal effects, frequent reciprocating shear and other complex conditions. Shear stability is an important indicator of the reliability of a magnetorheological media service. Magnetorheological grease (MRG) was prepared using hydroxy iron powder with a mass fraction of 30% and lithium grease of different consistency grades as a continuous phase. The results of magnetic and rheological properties analysis were combined to investigate the mechanism of the continuous thermal effect on the shear stability of MRG. The results show that changes in the temperature field and magnetic field cause significant changes in the magnetic and rheological properties of MRG. At low temperatures and low magnetic fields, the soap fiber structure unique to MRG can effectively inhibit the movement of magnetic particles, with slight changes in the rheological properties and excellent shear stability. When the temperature increases to 80 °C, 00#MRG is damaged by the high temperature. The soap fiber structure is fractured and reorganized, and the rheological properties change significantly. However, the rheological properties of 1#MRG remain largely unchanged during the magnetic field enhancement to saturation, showing better shear stability. The higher consistency continuous phase has excellent heat resistance and better shear performance stability in the face of thermomagnetic coupling conditions, but the fiber breakage caused by continuous reciprocating shear poses a challenge to the service stability of MRG.