A magnetorheological vibration absorber with bidirectional tunability for pipelines

Abstract

A magnetorheological elastomer (MRE) is employed as a tunable stiffness element in a dynamic vibration absorber (DVA) due to its remarkable magnetic tunability. However, the natural frequency of the MRE-based DVA can only be tuned towards high frequency under magnetic fields, which fails to solve, or even exacerbates, the low-frequency pipeline vibration. To tackle this issue, an innovative DVA (H-DVA) with bidirectional magnetic tunability is proposed in this paper. The hard magnetic MRE filled by NdFeB particles is selected as the core tunable stiffness element in H-DVA. Besides, the discretization distribution design scheme for the mass oscillators is adopted to improve the flexibility of H-DVA. Then, the magnetic field simulation and resonance frequency shifting test of H-DVA under different magnetic fields are completed to validate the bidirectional magnetic tunability. Lastly, the vibration absorption effect is verified in a self-established experimental pipeline system. The experiment results demonstrate that the resonance frequency of the proposed H-DVA exhibites a maximum frequency shift of approximately −2.7 Hz under reversed magnetic field. Compared to H-DVA working in zero field state, the acceleration magnitude of the pipeline vibration is further reduced by 8.8% when applying −1.5 A to the H-DVA under 55 Hz excitation. Similarly, the acceleration magnitude is further reduced by 22.2% when applying 2 A to the H-DVA under 85 Hz excitation. Thus, these findings confirm that the H-DVA proposed in this paper not only achieves the bidirectional magnetic tunability, but also improves the vibration absorption effect for pipeline vibration.