Design and test of an adaptive vibration absorber based on magnetorheological elastomers and a hybrid electromagnet

514

385

During the last few decades, magnetorheological (MR) elastomers have attracted a significant amount of attention for their enormous potential in engineering applications. Because they are a solid counterpart to MR fluids, MR elastomers exhibit a unique field-dependent material property when exposed to a magnetic field, and they overcome major issues faced in magnetorheological fluids, e.g. the deposition of iron particles, sealing problems and environmental contamination. Such advantages offer great potential for designing intelligent devices to be used in various engineering fields, especially in fields that involve vibration reduction and isolation. This paper presents a state of the art review on the recent progress of MR elastomer technology, with special emphasis on the research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, this review includes a brief introduction of MR elastomer materials and follows with a discussion of critical issues involved in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented on the research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices, and so on. A summary of the research on the modeling mechanical behavior for both the material and the devices is presented. Finally, the challenges and the potential facing magnetorheological elastomer technology are discussed, and suggestions have been made based on the authors' knowledge and experience. Abstract:During last decades, magnetorheological (MR) elastomer has attracted significant amount of attention for its enormous potentials in engineering applications. Being a solid counterpart of MR fluids, MR elastomers exhibit unique field-dependent material property when being exposed to magnetic field, in meanwhile overcoming major issues faced in magnetorheological fluids, e.g. deposition of iron particles, sealing problem and environmental contamination. Such advantages offer great potentials for designing intelligent devices to be used in various engineering fields, especially for vibration reduction and isolation. This paper presents a state-of-the-art review on the recent progress of MR elastomer technology, with special emphasis on research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, the review includes a brief introduction of the MR elastomer materials and follows by discussion of critical issues in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices and so on. Summary of research on modeling mechanical behavior for both material and devices are presented. Finally, challenges and potentials facing ...

Section: Operation Modesmentioning

confidence: 99%

A state-of-the-art review on magnetorheological elastomer devices

Li¹,

Li²,

Li³

et al. 2014

514

385

“…One of the novel designs that had to be developed for this study was an adjustable hybrid magnet system with permanent magnets and an electromagnetic coil. Although a similar idea can be found in [29] where a hybrid magnetic system was incorporated into an adaptive vibration absorber, the hybrid magnetic system designed and presented by this study differs significantly in its structure and operation compared to [29]. By including permanent magnets, a stable magnetic field could be applied to the laminated MRE and steel structure at all times without any power consumption.…”

Section: Design Of Hybrid Magnet Systemmentioning

confidence: 96%

A novel magnetorheological elastomer isolator with negative changing stiffness for vibration reduction

Yang

Sun

et al. 2014

112

Magneto-rheological elastomers (MREs) have attracted notable credits in the development of smart isolators and absorbers due to their controllable stiffness and damping properties. For the purpose of mitigating unwanted structural and/or machinery vibrations, the traditional MRE-based isolators have been generally proven effective because the MR effect can increase the stiffness when the magnetic field is strengthened. This study presents a novel MRE isolator that experienced reduced stiffness when the applied current was increased. This innovative work was accomplished by applying a hybrid magnet (electromagnet and permanent magnets) onto a multilayered MRE structure. To characterise this negative changing stiffness concept, a multilayered MRE isolator with a hybrid magnet was first designed, fabricated and then tested to measure its properties. An obvious reduction of the effective stiffness and natural frequency of the proposed MRE isolator occurred when the current was continuously adjusted. This device could also work as a conventional MRE isolator as its effective stiffness and natural frequency also increased when a negative current was applied. Further testing was carried out on a one-degree-of-freedom system to assess how effectively this device could isolate vibration. In this experiment, two cases were considered; in each case, the vibration of the primary system was obviously attenuated under ON-OFF control logic, thus demonstrating the feasibility of this novel design as an alternative adaptive vibration isolator.

“…Because of these unique properties, MREs have attracted increasing attention and gained broad application. With variable stiffness and damping under magnetic field, MREs are broadly applied in smart devices such as vibration absorbers [5][6][7][8][9][10], vibration isolators [11][12][13][14] and adaptive base isolators [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

The magnetic field dependent dynamic properties of magnetorheological elastomers based on hard magnetic particles

Wen

Wang

Gong

2017

In this study, novel magnetorheological elastomers based on hard magnetic particles (H-MREs) were developed and the magnetic field dependent dynamic properties of the H-MREs were further investigated. The storage modulus of H-MREs could not only be increased by increasing magnetic field but also be decreased by the increasing magnetic field of opposite orientation. For the anisotropic H-MREs with 80 wt% NdFeB particles, the field-induced increasing and decreasing modulus was 426 kPa and 118 kPa respectively. Moreover, the dynamic performances of H-MREs significantly depended on the pre-structure magnetic field, magnetizing field and test magnetic field. The H-MREs were initially magnetized and formed the chain-like microstructure by the pre-structure magnetic field. The field-induced increasing and decreasing modulus of H-MREs both raised with increasing of the magnetizing field. When the magnetizing field increased from 400 to 1200 kA m −1 , the field induced decreasing modulus of the 80 wt% isotropic H-MREs raised from 3 to 47 kPa. The magnetic field dependent curves of H-MREs' storage modulus were asymmetric if the magnetizing field was higher than the test magnetic field. Based on the dipolar model of MREs and magnetic properties of hard magnetic material, a reasonable explanation was proposed to understand the H-MREs' field dependent mechanical behaviors.