Fabrication of Biased-Magnetorheological Elastomers (B-MRE) Based on Magnetized Ferromagnetic Particles

摘要

Magnetorheological elastomers (MREs), like MR fluids, exploit magnetic forces between ferromagnetic particles toproduce a material with instantaneously adjustable properties of stiffness and damping with external magnetic fields. InMREs, the particles are a part of a structured elastomer matrix, and an external magnetic field is applied to achieve aninstantaneous change of stiffness due to magnetic forces between particles. A drawback of conventional MREs is itsinability of softening (reduce stiffness) under an external field. Many engineering applications need an instant change ofits stiffness in both directions, which requires a magnetic bias embedded in the MRE. One way is the use of a permanentmagnet (PM) for pre-straining a base elastomer matrix, but its mechanical design can be bulky due to the size of PM. Inthis paper, we address a fabrication process of the biased-magnetorheological elastomers (B-MREs) and their mechanicalproperties. The B-MREs consist of magnetized ferromagnetic particles as fillers and an elastomer as a binder. Themagnetization of ferromagnetic particles embedded in the elastomer matrix eliminates a need for the use of the PM andcan achieve the desired pre-strain in the B-MRE. The experiment results related with the mechanical properties aftermagnetization were presented. Also, different MRE thickness and weight ratios of the ferromagnetic particles mixed withthe base elastomer were compared in both normal and shear modes.