Magnetorheological (MR) materials are a group of smart materials used in new technologies with controlled reliability. The development of these materials is expanding, starting from MR fluids, elastomers, grease, and gel. This large number of material types further expands the various applications of MR materials as a creative technology to support performance enhancement. For example, MR fluid is used to improve the performance of shock absorbers such as vehicle suspension, the damping of building structures, and polishing of the workpiece. MR elastomers are used for engine mounting, insulation base, and many other applications with intelligent material properties such as stiffness controllability. However, there are still complexities in the practical implementation of the control system beyond reliability. Many previous studies have focused on the performance improvement and reliability of MR materials as smart materials for application devices and systems. In this review article, the specific discussion related to vibration control strategies in MR material-based systems was thoroughly investigated. To discuss this point, many MR applications including transportation system and vibration isolation were adopted using different types of control strategies. Many different control strategies that have been used for MR applications such as fuzzy logic control, optimal control, and skyhook control are discussed in-depth in terms of the inherent control characteristics of merits and demerits.
Building structures are vulnerable to the shocks caused by earthquakes. Buildings that have been destroyed by an earthquake are very detrimental in terms of material loss and mental trauma. However, technological developments now enable us to anticipate shocks from earthquakes and minimize losses. One of the technologies that has been used, and is currently being further developed, is a damping device that is fitted to the building structure. There are various types of damping devices, each with different characteristics and systems. Multiple studies on damping devices have resulted in the development of various types, such as friction dampers (FDs), tuned mass dampers (TMDs), and viscous dampers (VDs). However, studies on attenuation devices are mostly based on the type of system and can be divided into three categories, namely passive, active, and semi-active. As such, each type and system have their own advantages and disadvantages. This study investigated the efficacy of a magnetorheological (MR) damper, a viscous-type damping device with a semi-active system, in a simulation that applied the damper to the side of a building structure. Although MR dampers have been extensively used and developed as inter-story damping devices, very few studies have analyzed their models and controls even though both are equally important in controlled dampers for semi-active systems. Of the various types of models, the Bingham model is the most popular as indicated by the large number of publications available on the subject. Most models adapt the Bingham model because it is the most straightforward of all the models. Fuzzy controls are often used for MR dampers in both simulations and experiments. This review provides benefits for further investigation of building damping devices, especially semi-active damping devices that use magnetorheological fluids as working fluids. In particular, this paper provides fundamental material on modeling and control systems used in magnetorheological dampers for buildings. In fact, magnetorheological dampers are no less attractive than other damping devices, such as tuned mass dampers and other viscous dampers. Their reliability is related to the damping control, which could be turned into an interesting discussion for further investigation.
Magnetorheological materials based actuators have been currently exciting research topic for more than half-decades. Some actuators have been developed based on magnetorheological fluids and elastomers such as dampers, brakes, haptic devices, clutches, mountings, etc. These devices have their exciting properties which are capable of changing characteristic based on the amount of magnetic flux applied to them. Due to this capability, they are usually called semi-active devices. These devices employ an electromagnetic coil for magnetic flux production. Therefore, during the design process, magnetostatic simulation using the finite element method magnetic is carried out to make a better magnetic circuit. This chapter will consider several discussions such as necessary magnetostatic using free software finite element method magnetic (FEMM); design consideration for the magnetic circuit of the device and case studies of several type simulation in magnetorheological materials based devices.
Magnetorheological elastomers (MRE)-based products are usually located in an area directly exposed to sunlight and rain. However, there is no specific research on the behavior of MRE after accelerated weathering. Therefore, in this study, the changes to the chemical and rheological properties of both isotropic and anisotropic MRE after accelerated weathering were examined. Treated and untreated specimens were compared. MRE specimens with 40% by weight CIP were prepared with no current excitation and another sample was prepared with 1.5 T of magnetic flux density. Each specimen was treated in an accelerated weathering machine, Q-Sun Xe-1 Xenon Test Chamber, under a UV light exposure cycle and water spray. A material characterization was carried out using FTIR and a rheometer to determine the changes to the chemical and rheological properties. The morphological analysis results showed that after the weather treatment, the surface was rough and more cavities occurred. The rheometer test results showed a significant decrease in the storage modulus of each treated MRE specimen, unlike the untreated MRE specimens. The decrease in the storage modulus value with currents of 0, 1, 2, and 3 Amperes was 66.67%, 78.9%, 85.2%, and 80.5%, respectively. Meanwhile, FTIR testing showed a change in the wave peak between the untreated and treated MRE specimens. Thermogravimetric analysis (TGA) also showed a decrease in MRE weight for each specimen. However, for both treated and untreated MRE specimens, the decrease in TGA was not significantly different. In all the tests carried out on the MRE samples, weather acceleration treatment caused significant changes. This is an important consideration for developers who choose silicone as the MRE matrix.
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