Performance of natural rubber and silicone-based magnetorheological elastomers under large-strain combined axial and shear loading (original) (raw)
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Journal of Central South University, 2015
The preparation of natural rubber based isotropic thick magnetorheological elastomers (MRE) was focused on by varying the percentage volume concentration of carbonyl iron powder and developing a test set up to test the dynamic properties. Effect of magnetic field on the damping ratio was studied on the amplification region of the transmissibility curve. The viscoelastic dynamic damping nature of the elastomer was also studied by analyzing the force-displacement hysteresis graphs. The results show that MR effect increases with the increase in magnetic field as well as carbonyl iron powder particle concentration. It is observed that softer matrix material produces more MR effect. A maximum of 125% improvement in the loss factor is observed for the MRE with 25% carbonyl iron volume concentration. FEMM simulation shows that as carbonyl iron particle distribution becomes denser, MR effect is improved. FEMM analysis also reveals that if the distance between the adjacent iron particles are reduced from 20 μm to 10 μm, a 40% increase in stored energy is observed.
Dynamic properties of magnetorheological elastomers based on iron sand and natural rubber
Journal of Applied Polymer Science, 2014
In this study, magnetorheological elastomers (MREs) based on iron sand and natural rubber were prepared. The Taguchi method was employed to investigate the effect of a number of factors, namely, iron sand content, iron sand particle size and applied magnetic field during curing on tan δ and energy dissipated during cyclic loading. Tan δ was measured through dynamic mechanical analysis (DMA) over a range of frequency (0.01-130Hz), strain amplitude (0.1-4.5%), and temperature (-100-50 °C). Energy dissipated was measured using a universal tester under cyclic tensile loading. The data were then statistically analysed to predict the optimal combination of factors and finally experiments were conducted for verification. It was found that the iron sand content had the greatest influence on tan δ when measured over a range of frequency as well as energy dissipated during hysteresis tests. However, none of the factors showed significant influence on tan δ when measured over a range of strain amplitude. Furthermore, the iron sand content and magnetic field were also found to influence the width of the peak in tan δ as a function of temperature. The morphological characteristics of the MREs were also examined using scanning electron microscopy (SEM).
Mechanical properties of magnetorheological elastomers under shear deformation
Composites Part B: Engineering, 2012
In this paper, urethane magnetorheological elastomers (MREs) consisting of carbonyl-iron particles in a polyurethane matrix were studied. The volume fraction of particles was equal to 11.5%. Three types of ferromagnetic particles were used, with average particle size ranging from 1 to 70 lm. The elastic (storage) modulus G 0 was measured as a function of angular frequency x and strength of magnetic field. The measured G 0 values were approximated with empirical model. The highest magnetorheological effect has been found for samples with 6-9 lm carbonyl-iron powder. The highest increase in the yield stress is observed for samples with particles aligned at 30°to the magnetic field lines. It has been found that rheological properties strongly depend on the MRE microstructure, in particular on the size/shape of particles and their arrangement. By optimizing the particles size, shape and alignment, the stiffness of MREs has been increased under applied magnetic field.
Journal of Physics: Conference Series, 2016
This paper presents an investigation on the use of epoxidized natural rubber (ENR) as a matrix of magnetorheological elastomers (MREs). Isotropic ENR-based MRE samples were synthesized by homogeneously mixed the ENR compound with carbonyl iron particles (CIPs). The microstructure of the sample was observed, and the magnetic field-dependent moduli were analyzed using rheometer. The influences of excitation frequency, CIPs content and magnetic field on the field-dependent moduli of ENR-based MREs were evaluated through dynamic shear test. The microstructure of MRE samples demonstrated the dispersed CIPs in the ENR matrix. The remarkable increment of storage and loss moduli of the ENR-based MREs has exhibited the magnetically controllable storage and loss moduli of the samples when exposed to the magnetic field. Consequently, the CIPs content, frequency and magnetic field were significantly influenced the dynamic moduli of the ENR-based MREs.
Defence Science Journal
Magnetorheological Elastomers (MRE) endure a change in mechanical properties with the application of an externally applied magnetic field. It consists of an elastomeric matrix reinforced with ferromagnetic powdered particles. This paper focuses on the investigation of viscoelastic properties of Room Temperature Vulcanized (RTV) silicone based isotropic MRE in sandwich beam configuration by varying the volume percentage of Carbonyl Iron Powdered (CIP) reinforcement. Viscoelastic properties of the MRE core material were calculated by following the ASTM E756-05 standard. The magnetic field was applied by employing a Halbach array which was numerically analyzed using Finite Element Method Magnetics (FEMM). The magnetic field was varied up to 0.15 T. Loss factor and shear modulus were found to be strongly influenced by the percentage content of CIP. The loss factor and shear modulus of 30% MRE at 0.15 T were higher than other tested samples. The variation of natural frequency with respec...
Viscoelastic Properties of Magnetorheological Elastomers for Damping Applications
Macromolecular Materials and Engineering, 2014
Magnetorheological elastomers (MRE) have been synthesized on the basis of a silicon compound and a mixture of carbonyl iron particles of sizes 3-5 and 40-80 mm. Their viscoelastic properties have been studied by dynamic shear oscillations of various amplitudes on a stress controlled rheometer. The magnetic response of the obtained materials has been examined in a magnetic field applied perpendicular to the shear plane. It has been shown that under applied magnetic field both the storage G 0 and loss G 00 moduli became strain-dependent. The values of G 0 and G 00 decrease with strain, while their ratio (the loss factor), G 00 /G 0 , growths with strain. The higher magnetic field is the more pronounced the strain dependence is. At small strain (up to 1%) MRE demonstrate a giant (more than 10 times) increase of the moduli. Some features of hysteretic behavior of MRE under simultaneously applied magnetic field and external mechanical force have been elucidated. Temperature has a negligible effect on viscoelastic properties and stability of the developed MRE. A damper on the basis of MRE has been designed and its properties have been examined.
Magnetorheological elastomers: properties and applications
Proceedings of SPIE, 1999
A rheological model is described that was developed to simulate the dynamic behaviour of magnetorheological elastomers (MREs). The viscoelasticity of the polymer composite, magnetic field induced properties and interfacial slippage between the matrix and particles were modelled by analogy with a standard linear solid model, a stiffness variable spring and a spring-Coulomb friction slider respectively. The loading history and rate dependent constitutive relationships for MREs were derived from the rheological model. The hysteresis loop from shear strain -shear stress plots, which determines the shear modulus and loss factor, were obtained from substituting cyclic loading into these constitutive relationships. The dynamic behaviours of MREs were simulated by changing parameters in the rheological model to influence MREs' performances. The simulation results verified the effectiveness of the model.
Dynamic Characterization of Magneto-Rheological Elastomers in Shear Mode
IEEE Transactions on Magnetics, 2009
The paper presents dynamic shear properties of magneto-rheological elastomers (MREs) under various loading conditions. It particularly focuses on characterization of MREs under compression-shear type combined loading, as it represents realistic loading conditions in various engineering systems and structures. In this study, MRE samples were fabricated by curing a two component elastomer resin with 30% content of 10 m sized iron particles by volume. In order to vary the magnetic field during shear testing, a test fixture was designed and fabricated in which two permanent magnets could be variably positioned on either side of the specimen. By changing the distance between the magnets, the fixture allowed for varying the magnetic field that passes uniformly through the sample. Using this test setup and a dynamic test frame, a series of shear tests of MRE samples was performed by varying the magnetic field and frequency of loading. The results show the MR effect (percent increase in the materials "stiffness") increases as the magnetic field increases and loading frequency increases within the range of the magnetic field and input frequency considered in this study. The results further show that the elastic modulus of the precompressed MREs increases as compared with that of MREs without precompression.
Dynamic behavior of thick magnetorheological elastomers
SPIE Proceedings, 2012
This work is focused on the study of the dynamic behavior of thick magnetorheological elastomers at high frequencies. Experimental and theoretical studies are conducted to investigate the dynamic shear properties of magnetorheological elastomers which are affected by increasing the thickness, as well as the percentage of iron particles contained in magnetorheological elastomers. A double-shear test setup is designed and built to test the magnetorheological elastomer samples over a range of frequencies from 200 to 800 Hz. The results demonstrate that the thickness of magnetorheological elastomer significantly affects the material properties in the off-state, that is, when no magnetic field is applied. However, for the on-state, when the material is activated by a magnetic field, the thickness of the sample does not show a significant effect on the change in storage modulus induced by a magnetic field. The theoretical analysis includes a macromechanical model for the storage modulus and loss modulus of magnetorheological elastomer as a function of thickness, percentage of iron particles, and applied magnetic field. Comparisons between the theoretical and experimental results show that the model reasonably predicts the dynamic behavior of thick magnetorheological elastomers.