Isotropic Magnetorheological Elastomers Research Articles

Study on the damping properties of magnetorheological elastomers based on cis-polybutadiene rubber

Magnetorheological elastomers (MREs) are composed of magnetizable particles (iron particles) and a soft rubber-like matrix. Their mechanical properties, including modulus and damping capability, can be controlled by an external magnetic field. The damping properties of MREs, which play an important role in applications, depend mainly on particle content. This paper aims to investigate MRE's damping capabilities by studying two categories of cis-polybutadiene rubber-based MREs: isotropic and structured MREs. Both isotropic and structured MRE samples with various iron particle contents (60, 70, 80 and 85 wt%) were fabricated and their damping properties were measured by using a modified dynamic mechanical analyzer (DMA) and a universal testing machine. The results show that the loss factor in the glass transition region decreases with the increment of iron particle content. The loss factors of structured MREs are lower than those of isotropic MREs when the iron particle contents are the same. Furthermore, dynamic testing was conducted to study the effect of strain amplitude, frequency and magnetic field on the loss factor of MREs. In addition, the stress-softening experiments indicate that the ratio of remaining strain energy versus initial strain energy shows a decreasing trend with iron particle content and loading time.

Fabrication and characterization of isotropic magnetorheological elastomers

This paper presents a new method to fabricate isotropic magnetorheological (MR) elastomers under natural conditions. In the absence of a magnetic field, a variety of MR elastomer samples made of carbonyl iron particles, silicon rubber and silicone oil, were fabricated. Their dynamic viscoelastic properties were characterized by a measurement system developed by our group. Also, the microstructure of the samples was observed by a scanning electron microscope. The effects of iron particles and additives on the MR effect and the relationship between microstructure and mechanical properties were investigated. Furthermore, a simple self-assembled microstructure was proposed to explain the inherent magnetoviscoelasticity of MR elastomers prepared in the absence of a magnetic field. The analytical results of the model are in agreement with experimental data. The study is also expected to provide a good guide for designing and preparing new MR elastomers.