Magnetic Rubber Research Articles

Low frequency and broadband metamaterial absorber with cross arrays and a flaked iron powder magnetic composite

In this paper, we present a design, simulation and experimental measurement of a cross array metamaterial absorber (MMA) based on the flaked Carbonyl iron powder (CIP) filled rubber plate in the microwave regime. The metamaterial absorber is a layered structure consisting of multilayer periodic cross electric resonators, magnetic rubber plate and the ground metal plate. The MMA exhibits dual band absorbing property and the absorption can be tuned from 1∼8GHz in the same thickness depending on the dimension and position of the cross arrays. The obviously broadened absorbing band of the designed structure is a result of the synergistic effects of the electrical resonance of the cross arrays and intrinsic absorption of the magnetic layer. The polarization and oblique incident angle in TE and TM model are also investigated in detail to explore the absorbing mechanisms. The resonance current of the cross array can excite the enhanced local magnetic field and dielectric field which can promote the absorption. The measurement results are basically consistent with the simulations but the absorbing peaks move a little bit to higher frequency for the reason that the surface oxidation of the flaked CIP in the preparation process.

Magnetic Liquid Silicone Rubber – Revealing Effects and Process Limitations

SummaryAn example how to benchmark magnetic composites made of LSR, Liquid Silicone Rubber and magnetic filler for a potential application is given. A characteristic degree of filling was revealed appearing in viscosity, density and magnetic permeability investigations, consistently. A simple model is proposed to describe the magnetic permeability as a function of the degree of filling requiring only one adjustable parameter.

Fabrication of High Performance Magnetic Rubber from NBR and Fe3O4via in Situ Compatibilization with Zinc Dimethacrylate

Fe3O4-based magnetic rubbers are desirable because they take advantage of high elasticity, large elongations, and high magnetic saturation intensity of each component. However, direct compounding of rubbers and Fe3O4 usually resulted in low mechanical properties which made the magnetic rubbers unable to satisfy practical applications. In this paper, we prepared nitrile butadiene rubber (NBR)/Fe3O4-based magnetic rubbers with good mechanical properties by means of in situ compatibilization using zinc dimethacrylate (ZDMA). Our strategy was based on the polymerization of ZDMA during a peroxide-induced vulcanization, in which the polymerized ZDMA (PZDMA) brought massive Zn2+ ion pairs into NBR. Zn2+ ion pairs not only increased the polarity of NBR but also strongly interacted with Fe3O4 nanoparticles. Because of the graft-PZDMA, the Zn2+ ion pairs finally strengthened interactions between Fe3O4 nanoparticles and NBR molecules. We hope this report laid an applied foundation for design of high performance magn...

Ultra-thin Low-Frequency Broadband Microwave Absorber Based on Magnetic Medium and Metamaterial

An ultra-thin low-frequency broadband microwave absorber (MWA) based on a magnetic rubber plate (MRP) and cross-shaped structure (CSS) metamaterial (MM) was presented numerically and experimentally. The designed composite MWA is consisted of the MRP, CSS resonator, dielectric substrate and metallic background plane. The low-frequency absorption can be easily adjusted by tuning the geometric parameter of the CSS MM and the thickness of MPR. A bandwidth (i.e. the reflectance is below −10 dB) from 2.5 GHz to 5 GHz can be achieved with the total thickness of about 2 mm in experiments. The broadband absorption is attributed to the overlap of two resonant absorption peaks originated from MRP and CSS MM, respectively. More importantly, the thickness of the composite WMA is much thinner (λ/40; λ is the operation center frequency), which could operate well at wide incidence angles for both transverse electric and transverse magnetic waves. Thus, it can be expected that our design will be applicable in the area of eliminating microwave energy and electromagnetic stealth.

The Development of an Intelligent Hybrid Active-passive Vibration Isolator

A hybrid active-passive vibration isolator made up of electromagnetic actuator and air spring in parallel can be used to effectively isolate the broadband and line spectrum vibration of mechanical equipment simultaneously. However, due to its reliability and safety problems caused by the impact, its application in ships is limited. In this paper, an impact- resistant structure and an air gap self-sensing method of the passive-active hybrid vibration isolator are proposed and developed on the base of modelling, simulation and analysis. A thin magnetic rubber is filled into the air gap of electromagnetic actuator, which can avoid rigid collision between the armature and the permanent magnet under the action of impact. A suspension armature structure including pre-compression spring is suggested, which can automatically compensate the deformation caused by impact and protect the coil and permanent magnet from impact damage. An air gap self-sensing method is developed through detecting the voltage between the input and output terminals of actuator, which is verified by experiments.

Eversion of bistable shells under magnetic actuation: a model of nonlinear shapes

We model in closed form a proven bistable shell made from a magnetic rubber composite material. In particular, we incorporate a non-axisymmetrical displacement field, and we capture the nonlinear coupling between the actuated shape and the magnetic flux distribution around the shell. We are able to verify the bistable nature of the shell and we explore its eversion during magnetic actuation. We show that axisymmetrical eversion is natural for a perfect shell but that non-axisymmetrical eversion rapidly emerges under very small initial imperfections, as observed in experiments and in a computational analysis. We confirm the non-uniform shapes of shell and we study the stability of eversion by considering how the landscape of total potential and magnetic energies of the system changes during actuation.

A Study on Magnetic Property Improvement of Rubber Magnets for Heat Loss Reduction of a Refrigerator

A Study on Magnetic Property Improvement of Rubber Magnets for Heat Loss Reduction of a Refrigerator

Fabrication of magnetic rubber composites by recycling waste rubber powders via a microwave-assisted in situ surface modification and semi-devulcanization process

To effectively reuse waste rubber and reduce secondary pollution, a microwave-assisted in situ surface modification and semi-devulcanization route has been developed to fabricate magnetic rubber composites. The composites use waste rubber powders and ultrafine barium ferrite powders as starting materials without additional additives. Taking advantage of the microwave absorption capabilities of the barium ferrite powders and filling materials that exist in waste rubber, both the semi-devulcanization of the waste rubber powder and surface modification of barium ferrite powder have been simultaneously achieved under microwave irradiation. Thus, the phase compatibilities between barium ferrite and the rubber matrix are effectively improved, resulting in a low-cost fabrication of flexible magnetic composites with good ferromagnetic properties. The presented microwave assisted technique may also offer a novel path to design and produce organic–inorganic nano-composites.

Plasma characteristics and target erosion profile of racetrack-shaped RF magnetron plasma with weak rubber magnets for full circular target utilization

Abstract We have developed the racetrack-shaped RF magnetron plasma with weak rubber magnets (ferrite and neodymium) for the full utilization of the circular target and the reduction of the magnet weight. The magnetic field simulations are analyzed for the ferrite rubber magnets, the neodymium rubber magnets, and the neodymium rubber magnets including the neodymium metal magnets. The magnetic flux density indicates a mountain like profile between the magnets, having a maximum for the neodymium rubber and metal magnets. It is found that the ion flux to the target has a peak in the gap between two rubber magnets and the value remarkably increases with the addition of neodymium metal magnets. The erosion of the circular copper target, with 100 mm in diameter, has been studied by rotating the racetrack-shaped RF magnetron plasma for the neodymium rubber magnets including the neodymium metal magnets. It is seen that radial profile of the erosion depth keeps roughly constant until r = 20 mm and then decreases gradually away from the center for RF power of 40 W, Ar gas pressure of 2 Pa and sputtering time of 4 h. The target utilization is approximately 72% estimated from the erosion profile.

Preparation of magnetic rubber with high mechanical properties by latex compounding method

the magnetic rubber based on Fe3O4 nanoparticles and nature rubber were prepared by latex compounding method, in which stable Fe3O4 aqueous solutions were mixed with natural rubber latex and additives. This process was fast, versatile, reliable, safe, environmentally friendly and inexpensive. What’s more, it was found that the magnetic and mechanical properties of magnetic rubber increased together with increase in doping content of Fe3O4 nanoparticles. Especially, it was demonstrated that the tensile strength (25.0Mpa) of magnetic rubber was improved to be 478.0% comparing to neat natural rubber (5.2Mpa), which was 5 times higher than maximal value reported in previous work. At the same time, the magnetic rubber revealed better thermal stability and solvent resistance comparing to the neat natural rubber, too. The work dose not only provides a new way to environmentally friendly preparation of magnetic rubber at low temperature, but also improve the mechanical and magnetic properties of magnetic rubber applied in industry.

Optimization of Magnetizing Parameters for Multipole Magnetic Scales Using the Taguchi Method

Magnetic encoders are widely used to identify the position or travel distance in machine tools in a harsh environment. A magnetic encoder comprises a magnetic sensor and a magnetic scale, which is a permanent magnet strip magnetized into a multipole configuration. The pole pitch, magnetic flux density, periodicity, and symmetry of a magnetic field pattern are crucial for signal processing to obtain a satisfactory resolution. The magnetic flux density and the accuracy of a magnetic scale with a qualified permanent magnet strip are determined using magnetization technology. This paper focused on the optimization of perpendicular magnetizing parameters, using the Taguchi method, for designing a magnetizer to fabricate the high-quality magnetic scales made of rubber magnets. The parameters included the thickness of the magnetizer core, diameter of the magnet wire, magnetizing current, and magnetizing gap. The optimal parameters of magnetization were determined, and the reproducibility was validated. The average magnetic flux density was increased by $\sim 17$ % after optimization. In addition, the high-quality magnetic field pattern was achieved and it was advantageous for signal processing.

Smart damper using the combination of magnetic friction and pre-compressed rubber springs

This paper proposes a new concept of a smart damper using the combination of magnetic friction and rubber springs. The magnet provides energy dissipation, and the rubber springs with precompression contribute to increasing the recentering capacity of the damper. To verify their performance, dynamic tests of magnet frictional dampers and precompressed rubber springs were conducted. For this purpose, hexahedron neodymium (NdFeB) magnets and polyurethane rubber cylinders were used. In the dynamic tests, the loading frequency was varied from 0.1 to 2.0Hz. The magnets showed almost perfect rectangular behavior in the force–deformation curve, and the frictional coefficient of the magnets was estimated through averaging and regression. The rubber springs were tested with and without precompression. The rubber springs showed different loading path from the second cycle and residual deformation that was not recovered immediately. The rubber springs showed greater rigid force with increasing precompression. Finally, this paper discusses the combination of rigid-elastic behavior and friction to generate ‘flag-shaped’ behavior for a smart damper and suggests how to combine magnets and rubber springs to obtain flag-shaped behavior. The performance of the magnets and precompressed rubber springs was verified through analytical models.

스마트 댐퍼구현을 위한 자력마찰 댐퍼 성능실험

이 연구에서는 스마트 댐퍼 구현을 위한 자력마찰과 고무 스프링의 조합을 이용하는 기법에 대해서 제안을 했다. 자석의 에너지소산 능력을 비접촉과 접촉에 의한 기법을 비교하였다. 비접촉은 자기유도반발이고 접촉은 마찰력을 이용하는 방식으로, 접촉식이 에너지소산에서 월등히 우수한 것으로 나타났다. 자력마찰 댐퍼를 제작하여 동적 실험을 수행하여 자력마찰의 특성을 파악하였다. 자력에 의한 마찰은 일반마찰과 동일한 거동을 보였으며, 진동수가 증가에 따라 마찰계수가 거의 변하지 않는 것으로 파악되어 주파수 민감도가 없는 것으로 나타났다. 선압축 고무스프링은 강체-선형거동을 보이는데, 이와 자력마찰을 합성하면 깃발모양 거동의 스마트 댐퍼 개념을 제시하였다. This study suggests a method to embody a smart damper using magnetic friction and rubber springs. In this study, energy dissipation capacity of permanent magnets with and without contacting on a magnetic substance. Non-contacting method uses reaction from magnetic induction, and contacting method uses friction; the contacting method is superior to dissipate energy. After manufacturing a magnetic-frictional damper, this study conducts dynamic loading tests and investigates the characteristics of the damper. The magnetic-frictional damper shows the same frictional behavior with other types of friction and frictional coefficient of the damper does not vary so much with increasing loading frequency. A precompressive rubber spring shows rigid-elastic behavior and presents a flag-shaped behavior combining with magnetic friction, which can a smart damper.

Study on Damping Properties of Fe<sub>12</sub>O<sub>19</sub>Sr/NBR Composite

Magnetic damping composite was prepared by mechanical blending method. As acrylonitrile butadiene rubber was matrix, strontium ferrite magnetic powder was function phase. The vibrating sample magnetometer (VSM) test shows that the magnetic properties of the magnetic rubber composite are related with the content of the magnetic powder and unrelated with rubber matrix. The dynamic mechanical analysis (DMA) and TA method compare show that the damping properties of the composite are improved with adding the strontium ferrite magnetic particle, but the damping properties of composite are best after magnetizing the sample, but the damping properties of the composites decreased with increasing the content of the magnetic powder. The damping properties of the composites at the test frequency 30HZ and 50HZ are higher than 1HZ.

Influence of Magnetic Conductive Rubber on Maglev Actuator in Active Vibration Control

Theoretical and finite element models of maglev actuator are both established. Magnetic conductive rubber is added into the actuator to improve its performance. Numerical simulations and experiments show that adding conductive rubber increases the output force-power ratio while reduces the dynamic response slightly.

Preliminary validation of Sm–Fe–N magnetic silicone rubber for a flexible magnetic actuator

In this paper, we present a new approach for a flexible magnetic actuator (FMA) using Sm–Fe–N magnetic silicone rubber (MSR) that has a higher degree of freedom (DOF) in shape, flexibility, ease of fabrication and combinative ability than permanent magnets. To verify its potential for use in an FMA, we examined its magnetic and elastic properties and focused on magnetic torque control within a uniform rotating magnetic field. Silicone rubber liquid and hardener were mixed with Sm–Fe–N powder and poured into a mold. The fabricated Sm–Fe–N MSR included Sm–Fe–N powder of 13.5, 17.3, and 21.2 vol% ratio. The physical and elastic properties were determined by a vibrating sample magnetometer (VSM) and elastic load, respectively. Furthermore, we fabricated two FMAs (multiple-magnetic anisotropy type and spiral-type), and evaluated the suitability of the Sm–Fe–N MSR for magnetic wireless actuators based on magnetic torque control.

Adjustable low frequency and broadband metamaterial absorber based on magnetic rubber plate and cross resonator

In this paper, the magnetic rubber plate absorber (MRPA) and metamaterial absorber (MA) based on MRP substrate were proposed and studied numerically and experimentally. Based on the characteristic of L-C resonances, experimental results show that the MA composed of cross resonator (CR) embedded single layer MRP could be adjustable easily by changing the wire length and width of CR structure and MRP thickness. Finally, experimental results show that the MA composed of CR-embedded two layers MRP with the total thickness of 2.42 mm exhibit a −10 dB absorption bandwidth from 1.65 GHz to 3.7 GHz, which is 1.86 times wider than the same thickness MRPA.

Magnetic silicone rubber: Fabrication and analysis with applications

In this research, we fabricated magnetic silicone rubbers (MSR) by using magnetic powders of Fe or Sr ferrite (ϕ 3–5 um) and investigated the physical properties of the MSR, such as the elastic and the magnetic characteristics. MSR is a new approach to flexible magnetic actuators. If the MSR is to be solidified, the mixing ratio between a silicone elastomer and the magnetic powders is important. In addition, the ratio determines the magnetic properties in a magnetic field. If soft magnetic powders are used in the MSR, magnetic force control is possible. We applied MSR to an electromagnetic linear actuator to verify the capability of MSR based on Fe or Sr ferrite materials. In the linear actuator for inchworm motion, MSR improved the magnetic force and the velocity. MSR can provide a simple mechanism for robotic applications and magnetic artificial muscles.

Heat-resistant antiflaming and friction mechanisms in nano-Fe2O3-reinforced silicon rubber

Abstract A ferric oxide (Fe2O3)/silicone rubber (SR) composite was prepared to produce a magnetic rubber with good heat-resistant and friction properties: SR and nano-Fe2O3 were used as its raw materials. The heat-resistant, antiflaming, magnetic, and mechanical properties of such composites with different proportions of nano-Fe2O3 were studied. The results showed that the Fe2O3 nanoparticles were uniformly distributed throughout the composites. The physical and mechanical properties of SR were improved when Fe2O3 nanoparticles were added. The maximum elongation and tensile strength of the composites were relatively good when the ratio of Fe2O3 was 20 phr. The heat-resistance and antiflaming properties of SR were improved by adding nano-Fe2O3, which had good combined heat resistance. The friction properties of these composites were optimal at 20 phr addition of nano-Fe2O3, which laid the foundation for further applications of this type of composite in high-temperature sealing and shock absorption environments.

High damping properties of magnetic particles doped rubber composites at wide frequency

A new kind of rubber composite was prepared by doping SrFe12O19 nanoparticles coated with silane coupling agents (Si-69) into nitrile butadiene rubber (NBR) matrix, which was characterized by the scanning electron microscopy and X-ray spectroscopy. The results showed that the SrFe12O19 nanoparticles were well dispersed in rubber matrix. Furthermore, the mechanical and magnetic properties of the rubber composites were investigated, in which the high tensile strength (15.8MPa) and high saturation magnetization (22.9emu/g) were observed. What is more, the high loss factor of the rubber composites was also obtained in a wide frequency range (0–100Hz) at high loading (80phr). The result is attributed to that the permanent magnetic field in rubber nanocomposites can absorb shock energy. These results indicate that the new kind of permanent magnetic rubber is expected to be a smart isolator material, in which the isolator will be able to adapt to a changed frequency.