A Novel MRE Adaptive Seismic Isolator Using Curvelet Transform Identification (original) (raw)

Characterization of Magneto-Rheological Elastomer and Modelling of MRE Based Isolators

2018

Magneto rheological elastomer (MRE) is a new kind of smart material whose dynamic properties can be altered in the real time with an externally applied magnetic field. This advantage of MRE has brought up its application to the development of real time adaptable base isolation systems, with ability to change the stiffness and damping according to applied magnetic field. The MRE base isolator generally consist of a laminated layer of MR elastomer sheets and steel sheets, sandwiched between two thick steel plates one at top and other at bottom, and enclosed by a current carrying coil. Current in the coil generates magnetic field which alter the stiffness and damping of the isolator and by controlling the current, the required stiffness and damping can be achieved. In this study, characterization and modelling of the current dependent visco-elastic properties of synthetic rubber based MRE is carried out. Synthetic rubber based MRE were fabricated with magneto-sensitive carbonyl iron (C...

IRJET- Magnetorheological Elastomeric Base Isolator for Seismic Protection

IRJET, 2020

Base isolator is one of the most effective technique in decreasing earthquake force that transmits to the building However, conventional passive base isolators have to be provided with large seismic gaps due to their high horizontal flexibility and exhibits poor adaptability to varying ground excitations. Hence it becomes necessary to introduce "smartness", in the conventional base isolators and enhance their adaptability to varying spectra of input loads. As a new branch of rheological smart material, magnetorheological elastomer (MRE) can be controlled rapidly and reversibly by the application of magnetic field. Compared to MR fluid devices, MRE devices can provide tunable stiffness and damping without worrying about the leakage and settlement problems. Therefore, an increasing number of researchers have shown their interest to the material, and lots of innovative MRE devices have been proposed in recent years. The present study aims at proposing an innovative laminated model of magnetorheological elastomeric base isolator by conducting a finite element study on the laminated portion of the bearing and provide a design specification for the MRE isolators. Analytical results show that incorporation of magnetic particles into the elastomeric medium can increase the energy dissipation capacity of the isolator and it can bring out a significant reduction in the size of isolator during design phase.

Response Analysis of Isotropic and Anisotropic Magnetorheological Elastomer

The purpose of this paper is to research the response of isotropic and anisotropic Magnetorheological Elastomer (MRE) with 15 and 30 percent of iron particles comprising in matrix of MRE with respect to transmissibility and percentage of vibration absorption. Fabrication and experimental investigation were carried out to study the response of MREs with respect to transmissibility and percentage of vibration absorption by using fast fourier transform (FFT). To ensure the validation of experimental result different readings were taken to compare characteristics in different loading conditions. Result obtained from the experimental analysis of samples of isotropic and anisotropic MREs with with 15 and 30 percent of iron particles were compared. Result show that best performance of vibration control and transmissibility were obtained with fabrication of anisotropic and isotropic MRE with 30 gm iron particle behind that anisotropic and isotropic MRE with 15 gm iron particle have good results of vibration control.

Development and Characterization of Isotropic Magnetorheological Elastomer

Universal Journal of Mechanical Engineering, 2013

Magneto rheological elastomer (MRE) is a new kind of smart materials. Its dynamic mechanical performances can be controlled by controlling an applied magnetic field. MRE is usually used as stiffness-changeable spring in the semi-active vibration absorber. In order to get perfect vibration control effect, low dynamic damping of MRE is needed. This paper presents a new method of fabricating isotropic MREs under normal temperature and pressure conditions. In the absence of a magnetic field, a variety of MR elastomer samples were prepared using Sylard's184 silicone elastomer along with un-annealed electrolytic iron power 500 mesh and 15 micron size. Their dynamic characteristics like fractional change in resonant frequency and fractional change in have been studied. The effects of iron particles and the applied magnetic field were investigated. This study is also expected to provide a good guide for designing and preparing new MR elastomers.

Dynamic Properties of Magnetorheologic Elastomer

Rakenteiden Mekaniikka, 2007

SUMMARY Machinery and buildings often have to be protected from vibrations. The needed reduction of dynamic response can be achieved efficiently with semi-active isolation. One way to use semi-active isolation is to install vibration isolators between the base and the object to be protected and control the dynamic properties of these isolators. The advantage of semiactive isolation compared to passive isolation is the adjustability of the system. With adaptive semi-active isolators it is possible to react simultaneously to the changes of the loads and dynamics of the system. This paper describes the laboratory tests and the measurement results of an improved vibration isolator material and an improved adaptive vibration isolator developed by the Technical Research Centre of Finland (VTT). On the basis of the results the presented adaptive material and isolator system is applicable for typical industrial and transportation environments.

Morphological Analysis of Unstructured and Prestructured Magneto-rheological Elastomer

International Journal for Research in Applied Science and Engineering Technology (IJRASET) , 2021

By providing or not put on a magnetic flux, a magneto rheological (MR) elastomer becomes a very powerful and advanced smart material that could be twisted and responded hurriedly in relations of mechanical strength. They are elastomer materials with embedded iron elements in an elastomer environment. Isotropic(unstructured) and anisotropic(prestructured) MR elastomers are categorized built on the submission of a magnetic flux during in the fabrication process. The scattering of magnetizable elements in the medium of an elastomer is well defined and arranged by kind. Scanning Electron Microscopy(SEM) had revealed their shape. They should be employed in a variability of solicitations payable to their improved morphological characteristics, such as pulsation absorbers, isolators, seismic devices, and so on.

Study of magnetorheology and sensing capabilities of MR elastomers

Journal of Physics: Conference Series, 2013

This study focuses on the magnetorheology and sensing capability of graphite based Magnetorheological Elastomers (Gr MREs). By introducing graphite (Gr) to conventional MREs, the Gr MREs are derived. The anisotropic sample with 20% graphite weight fraction was selected to be compared with anisotropic conventional MREs. The microstructures of anisotropic Gr MREs and conventional MREs were observed. Both steady state tests and dynamic tests were conducted to study rheological properties of the samples. For dynamic tests, the effects of strain amplitude, and frequency on both storage modulus and loss modulus were measured. For sensing capability, the resistance of selected Gr MREs under different magnetic fields and external loadings is measured with a multi-meter. Either higher magnetic field or more external loading results in the resistance increment. Based on an ideal assumption of perfect chain structure, a mathematical model was proposed to investigate the relationship between the MRE resistance with the external loadings. In this model, the current flowing through the chain structure consists of both tunnel current and conductivity current, both of which depends on external loadings. The modelling parameters were identified and reconstructed from comparison with experimental results. The comparison indicates that both experimental results and modelling prediction agree favourably well.

Implementation of functionalized multiwall carbon nanotubes on magnetorheological elastomer

Journal of Materials Science, 2018

This work studies the effects of loading various functionalized multiwall carbon nanotubes (carboxyl,-COOH-MWCNTs) on the morphological and the fielddependent rheological properties of magnetorheological elastomers (MREs). A new type of MRE, which is reinforced by various loading from 0 to 1.5 wt% of COOH-MWCNT, is fabricated and experimentally investigated. The morphology of COOH-MWCNT and MRE with COOH-MWCNTs is characterized using field emission scanning electron microscopy and transmission electron microscopy. The results indicate that the COOH-MWCNTs are well embedded and dispersed randomly in the MRE structures. The rheological properties under different magnetic fields are evaluated using parallel plate rheometers. The influence of COOH-MWCNT content on the viscoelastic performance of the MRE is systematically investigated. It is found that when a higher content of COOH-MWCNT (up to 1.0 wt%) is added in the MRE, the MRE exhibits a higher MR effect of up to 17.5%. It is also shown that COOH-MWCNT acts as a reinforcing agent that leads to an enhancement in MR performance. Abbreviation MR Magnetorheological MRE Magnetorheological elastomer MRF Magnetorheological fluid MRG Magnetorheological grease NR Natural rubber SMR Standard Malaysia rubber CIP Carbonyl iron particle COOH-MWCNT Carboxyl multiwall carbon nanotubes EPO Epoxidized palm oil G 0 Storage modulus G 0 0 Storage modulus (without magnetic field) FESEM Field emission scanning electron microscopy