Experimental and numerical research of stress relaxation behavior of magnetorheological elastomer

Abstract

The paper presents experimental research and viscoelastic modeling of stress relaxation response of isotropic magnetorheological elastomer (MRE). The isotropic MRE has been prepared based on silicone matrix filled by magnetically micro-sized carbonyl iron particles. Effects of constant strain level and external magnetic field on the stress relaxation behavior of the MRE were carefully investigated by single- and multi-step relaxation tests in shear mode using double-lap shear specimens. Results revealed that the stress relaxation response of the MRE was dependent on the applied constant strain and external magnetic field. The relaxed stress and modulus of the MRE increased with increasing the constant strain level. In addition, the values of absolute stress and modulus in the relaxation periods enhanced with the rise of magnetic flux density. A four-parameter fractional derivative viscoelastic model was used to describe the stress relaxation behavior of the MRE. The studied model was fitted well to experimental data of the MRE in both single- and multi-step relaxation tests. The fitting of shear-stress relaxation modulus for the MRE is in a very good agreement with the experimental one. Effects of applied constant strain and magnetic field intensity on the fitted parameters were discussed. Moreover, the model can be applied to predict accurately the long-term relaxation behavior of the MRE.