Discrete fiber skeleton strengthened magnetorheological grease and a novel H–B model based on fiber parameters

Magnetorheological fluid (MRF) porous fabric composite has been demonstrated to improve the shear properties of MRF. Non-woven fabric is manufactured from a multitude of fibers through spinning or melt-blown processing methods. As the fundamental unit of non-woven fabric, fibers without spinning or melt-blown directly influence the shear properties of magnetorheological (MR) materials. However, the effect of unprocessed fiber on the shear properties of MR grease remains uncertain. This study introduces a novel MR grease with fiber threads (MRG-FT) by incorporating fiber threads into MRG. The effects of fiber thread length, mass fraction, and material type on MRG shear stress are investigated. Compared to conventional MRG, the maximum shear stress of MRG-FT is increased by 31.8% under the magnetic field of 0.64 T. A novel Herschel–Bulkley–Fiber (H-B-F) model that considers fiber parameters (tenacity, mass fraction, etc.) is proposed based on the H–B model. To validate the enhancement of MRG by fiber threads, a linear damper based on shear mode has been designed and tested. The results demonstrate a 23.8% increase in the maximum damping force of MRG-FT compared to conventional MRG under an excitation current of 1.6 A. This study reveals the influence of fiber threads, which directly influences the shear properties of MRG upon the application of the magnetic field. The maximum damping force of the MRG can be increased by 23.8% by only 1.5% mass fraction of fibers.