The impact of CIP content on the field-dependent dynamic viscoelastic properties of MR gels

Magnetorheological (MR) gels are one of the categories of magnetic smart materials, whose mechanical properties changed significantly in the presence of a magnetic field. This paper present dynamic viscoelastic properties of MR gel under various of magnetic flux density and Carbonyl iron powders (CIPs) weight fraction. The test to understand the dynamic rheological properties are carried out using oscillatory shear. Firstly, the MR gels are prepared by dispersing the CIPs into polyurethane (PU) matrix with a mechanical stirrer. Experimental data are obtained by changing the magnetic flux density from 0 mT to 480 mT at room temperature of 25 degrees C. The elastic stress of MR gels with different CIPs content was studied under different magnetic flux density in oscillating test environment. The study results display that the elastic stress increases with strengthening extra magnetic flux density and the shape of elastic stress-strain curves are different under various magnetic flux density. Initial modulus, magneto-induced modulus and MR effect of MR gels with different contents of CIPs were obtained by magnetic field scanning. The results show that a higher magnetic-induced storage modulus can be obtained at higher CIPs weight fraction. The critical values and static elastic yield stress of MR gels with different CIPs content are also obtained by shear stress vs shear strain curves at the different magnetic flux density.