Due to advantages like larger force, controllability and fast response, magnetorheological (MR) materials have been proven to be valuable in many critical engineering applications for vibration suppression. In this paper, a novel multi-stage shear mode MR damper with composite lithium-based MR grease has been designed, fabricated and tested for industrial pipe with small amplitude and medium-high frequency excitations. Firstly, a multi-stage shear mode MR damper with linear motions has been proposed. It can produce a larger damping force with the lower frequency sensitivity which is more suitable for medium-high frequency vibration isolation. Then, a novel composite lithium-based MR grease is prepared and measured. The maximum yield shear stress is increased by 166.7% at off-state and the maximum MR effect is also increased by 19.1% than conventional single-matrix MR grease. Considering the distribution of magnetic fields, an improved model is proposed which can precisely describe the output performance. Moreover, the mechanical properties of the prototype and the pipe vibration isolation system have been tested and analyzed comparatively. The damping force and dynamic stiffness of the prototype increase with increasing the applied currents and excitations. The maximum damping force is larger than 5 kN at the amplitude of 1 mm. The peak acceleration of the improved pipeline system changes from 17.39 m/s² to 9.87 m/s² with a decrease of 43.24%. The tested results show that the vibration of industrial pipe can be significantly suppressed by the multi-stage shear mode MR damper.

magnetorheological damper,multi-stage,composite grease,industrial pipe