Rotor vibration control using hybrid magneto-rheological elastomer rings

Magnetorheological elastomers (MREs) are magneto-active smart materials consisting of micron-sized ferromagnetic particles embedded in an elastomeric matrix. This paper presents a dynamic analysis of a novel hybrid MRE ring designed for vibration control of rotor system. The proposed hybrid MRE comprises alternating sectors of silicone rubber-based MRE (MRE-SR) and polydimethylsiloxane-based MRE (MRE-PDMS). The rheological properties of these two smart materials, particularly the storage modulus and the loss modulus, are derived from the literature. To assess the effectiveness of the hybrid design, its vibration responses are compared with those of conventional MRE-SR and MRE-PDMS rings. Frequency-dependent stiffness and loss factors of all MRE variants are first characterized under identical magnetic fields to assess their viscoelastic properties. A rotor system supported by MRE ring bearings is then modeled and analyzed, to evaluate vibration responses and resonant speeds across rotating speeds. The results reveal that the hybrid MRE presents compromised dynamic characteristics between the two single-material rings. Compared to MRE-PDMS, the hybrid reduces vibration amplitude by up to 76.9% at the first critical speed and 34.8% at the second critical speed. When the magnetic field is applied, the vibration amplitude increases at resonance speeds while decreasing at other ranges of rotational speeds.