Shear band formation in magnetorheological elastomer under stress relaxation

Abstract

The characteristics and behaviors of magnetorheological elastomer (MRE) within the elastic region are significantly important to demonstrate potentiality toward infinitesimal deformation in various applications. As MRE dynamically shears within an elastic region at constant small deformation, its significant consequence has long been a pending topic, hampered partly by the lack of empirical evidence. Therefore, this paper aimed to investigate the onset microscopically transformation of the MRE sample precipitated to storage modulus behavior under stress relaxation conditions. To achieve the aim, MRE with 70 wt% carbonyl iron particles was dynamically sheared at 1 Hz frequency and 0.01% strain for a designated period of test duration. The morphology evaluation of the sheared sample disclosed the development of permanent microplasticity in a very narrow region of shear bands. The deformation adequately reduced the storing energy ability of the MRE at a dominantly elastic behavior. The results revealed that the ability of MRE to store deformation energy slightly reduced by 0.3%-0.5% for the 2000 s test interval. This interesting onset phenomenon was successfully achieved, and the establishment of this early-stage deformation was undeniably important as preliminary data for catastrophic investigation at a longer duration.