Development and Experimental Study of a Mixed-Mode Vibration Isolator Using Magnetorheological Elastomer

Vibration isolation is a most widely used vibration protection method.The stiffness of vibration isolators in existing conventional type of vibration isolation system is usually of fixed value. This limits the system in exhibiting its vibration isolation effect in that, it has poor results for lower frequency vibration, especially for resonance frequency. Magneto-rheological elastomer is a new branch of Magneto-rheological materials. It’s an intelligent materials in that it’s shear modulus can be controlled by a magnetic field. It has wide application prospects in the vibration control area. This paper proposes using adjustable stiffness of magneto-rheological elastomer vibration isolation in vibration isolation system. By changing the current of vibration isolators coil to control the shear modulus of magneto-rheological elastomer, it can adjust the stiffness of the isolation system, making the system obtain wider vibration isolation frequency range. By exploying SimuLink software to analyze the vibration isolation system, it is found that such a design is effective and applicable.

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.

Magnetorheological Elastomer (MRE) is a type of smart composite material consisting of a polymer matrix embedded with ferromagnetic particles. In the presence of an external magnetic field, its mechanical properties, such as stiffness, changes make it attractive in vibration isolation applications. Unwanted vibration in machines can cause severe damage and machine breakdown. In Qatar, the extraction of the natural gas from the ground requires sophisticated drilling machines. In this work, a semi-active vibration isolator using MRE is proposed for a potential application in a drilling system to isolate the torsional vibration. MRE was fabricated with a 35% mass fraction (MF) consisting of silicon rubber and iron particles. It was fitted with aluminum couplers and attached to the shaft (drill string) to study its efficiency in vibration isolation under a magnetic field. Two tests were conducted on the drilling prototype setup used in this work; the first test was a hammer impact test. The torsional transfer function TTF analysis showed that the system's natural frequency has shifted from 13.9 Hz to 17.5 Hz by the influence of increasing magnetic field around the MRE. The results showed that the continuous rotational vibration amplitude of the prototype is attenuated by more than 40%.

A novel lateral vibration isolator utilizing magnetorheo logical elastomers (MREs) with the field-dependent d amping and stiffness was proposed in order to improve the adaptive performance. First, soft silicone rubber MREs with a highlyadjustable shear storage mo dulus was fabricated. Then , the lateral MREs isolator was dev eloped with a uniqu e laminated structure of MRE layers and steel p lates, which enables to withstand larg e vertical loads and adapts to the situation of large lateral displacement. Also, the electromagnetic analysis and design employed electromagnetic finite element method (FEM) to optimize magnetic circuit inside the proposed device. To evaluate the effectiveness of the lateral MREs isolator, a series of experimental tests were carried o ut und er variou s app lied magnetic fields. Experimental results show that the proposed MREs isolato r can triumphantly change the lateral stiffness and eq uivalent damping up to 140% and 125%, respectively. This work demo nstrates the performance of the designed lateral MREs isolator and itscapacity in vibration mitigation for the complex situation. Keywords: Magnetorheological elastomers, finite element method, isolator, vibration mitigation

The design and optimization of magnetorheological elastomer (MRE) isolators fundamentally dictate their ultimate performance and application potential. Current methods are limited by over-reliance on designer’s personal experience or inability to concurrently optimize structural configuration and performance parameters. To address these limitations, this study proposes a synergistic design method for MRE isolator, combining extended-variable tri-phase topology optimization and multi-objective parameter optimization. The tri-phase method expands design variables from [0, 1] to [−1, 1], enabling simultaneous optimization of the excitation coil, magnetic circuit and air region without increasing dimensionality, thus yielding a lightweight configuration of MRE isolator. It overcomes the drawback of traditional optimization methods that require predefined of structural configurations. Based on the topological results, a parametric model is constructed, and a multi-objective optimization method (coupling NSGA-II genetic algorithm with finite element simulation) is developed to derive the Pareto frontier. This frontier resolves design trade-offs among the ‘magnetic field–energy consumption–lightweighting’ of MRE isolator. An optimal design is selected from the feasible solution space, achieving minimal mass while maintaining an 89th-percentile magnetic energy ratio. Experimental validation confirms the design’s adaptive vibration mitigation performance and manufacturability. This work establishes a systematic and scalable methodology that bridges empirical design and data-driven optimization, applicable to MRE isolators and other electromagnetic smart devices.

In this study, 3D printed magnetorheological (MR) elastomer has been characterized through a force vibration testing. The 3D printed MR elastomer is a composite consisting three different materials, magnetic particles and two different elastomers. The MR elastomers were printed layer-by-layer by encapsulating MR fluid within the polymeric elastomer and then allowed to cure at room temperature. The 3D printing allowed to print various patterns of magnetic particles within the elastomeric matrix. In the presence of an external magnetic field, both elastic and damping properties of the 3D printed MR elastomers were changed. Natural frequency, stiffness, damping ratio, damping coefficient, and shear modulus were increased with increasing magnetic field. For the single degree-of-freedoms system, shear mode MR elastomers suppressed the transmitted vibration amplitude up to 31.4% when the magnetic field was 550 mT. The results showed that the 3D printed MR elastomer could be used as a tunable spring element for vibration absorption or isolation applications. However, further optimization of the magnetic particles’ configurations should be performed to obtain the higher MR effect.

Magnetorheological elastomer is a new intelligent material, which shows a promising application prospect in the intelligent control area. In the molding of magnetorheological elastomer, vulcanization under magnetic field condition is the critical step. However, the traditionally used vulcanization apparatus cannot be applied in the preparation of magnetorheological elastomer directly for the unavailable magnetic field, uneven pressure, and serious heat dissipation. An improved vulcanization apparatus with magnetic field generator, support device, and temperature control device was designed. To ensure the rationality of the designs, magnetic circuit simulation, thermal simulation, and stiffness consistency test were conducted. Experimental tests showed that the vulcanization apparatus we designed applied well in the preparation of magnetorheological elastomers and magnetorheological elastomer isolator.

The vehicle‐mounted equipment is easy to be disturbed by external vibration excitations during transportation, which is harmful to the measurement accuracy and performance of the equipment. Aiming at the vibration isolation of the vehicle‐mounted equipment, a semiactively controlled quasi‐zero stiffness (QZS) vibration isolator with positive and negative stiffness is proposed. The vertical spring is paralleled with a magnetorheological (MR) damper, and the semiactive on‐off control scheme is adopted to control the vibration. The analytical expression of the isolator’s displacement transmissibility is derived via the averaging method. Then, the vibration isolation performance under different road excitations and different driving speeds is simulated and compared with the uncontrolled passive QZS vibration isolator. In addition, the mechanical structure of the semiactive QZS isolator is designed and manufactured, and the test system is built by LabVIEW software and PXI embedded system. The isolation effect of the semiactive QZS isolator is verified through test data. It is found that the proposed semiactive QZS isolator shows excellent vibration isolation performance under various road excitations, while the passive QZS isolator is effective only under harmonic excitations. The vertical acceleration of vehicle‐mounted device can be decreased over 70% after isolation, and the vibration isolation effect is remarkable. The design idea and research results of the semiactive QZS isolator may provide theoretical guidance and engineering reference for vibration isolation.

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.

Negative Poisson’s ratio materials are increasingly used in the design of vibration isolation bases due to their unique tensile properties. In this paper, based on the expansion feature of the negative Poisson’s ratio re-entrant structure, the influence of the size of the re-entrant structure within a single structure was analyzed, and a honeycomb base was designed with a negative Poisson’s ratio re-entrant structure. A new modeling method for the honeycomb base is proposed. In the modeling process, the honeycomb base was analyzed according to its symmetry using the Lagrange equation for base modeling and the finite element consistent mass matrix was introduced to simplify the calculation. The vibration isolation performance of the honeycomb base was evaluated by vibration level difference. COMSOL software was used to simulate and analyze the cellular base in order to verify the correctness of the results obtained from numerical modeling. In conclusion, the honeycomb base had a vibration isolation effect on external excitation in the vertical direction of the base. Furthermore, the vibration isolation performance of the base was greatly related to the wall thickness and Poisson’s ratio of the re-entrant structure.

Investigation of a new metamaterial magnetorheological elastomer isolator with tunable vibration bandgaps

Magneto Rheological Elastomers (MREs) are composite materials based on an elastomer filled by magnetic particles. Anisotropic MRE can be easily manufactured by curing the material under homogeneous magnetic field which creates column of particles. The magnetic and elastic properties are actually coupled making these MREs suitable for energy conversion. From these remarkable properties, an energy harvesting device is considered through the application of a DC bias magnetic induction on two MREs as a metal piece is applying an AC shear strain on them. Such strain therefore changes the permeabilities of the elastomers, hence generating an AC magnetic induction which can be converted into AC electrical signal with the help of a coil. The device is simulated with a Finite Element Method software to examine the effect of the MRE parameters, the DC bias magnetic induction and applied shear strain (amplitude and frequency) on the resulting electrical signal.

Active and Semi Active Vibration Isolation Systems Based on Magnetorheological Materials

The quasi-zero stiffness(QZS) nonlinear isolators have been paid much attention in recent literatures due to their excellent vibration isolation performance under low frequency excitation compared to traditional linear vibration isolators. However, passive QZS isolators are the most widely studied and they are incapable of dealing with varying conditions such as changing the excitation frequency or load in operating state. To promote the adaptability of QZS isolators, a novel approach to achieve real-time controllable QZS is proposed in this paper. An electromagnetic negative stiffness unit comprised of two electromagnet with MR elastomer is employed to produce negative stiffness, and the stiffness characteristic of the system can be accurately controlled by adjusting the driving current according to the displacement information in real time. Theoretical calculation and finite element analysis is conducted to establish the exact model of electromagnetic force followed by the general design of the system. Then a customized driver is developed for electromagnetic negative stiffness unit, and the dynamic model of the isolator is set up to study the effect of relative parameters on the transmissibility. Finally, a series of experiments are performed to evaluate the real-time controllable QZS characteristic and confirm the vibration isolation effect of the proposed electromagnetic QZS isolator.

A new self-sensing bearing based on magneto-rheological elastomers (MREs) was proposed in this paper. For the application in vibration isolation system, the effects of force field and magnetic field on the self-sensing characteristics were simultaneously investigated. Based on the modified MRE, the small-scaled bearing experimental system was built. The results confirmed that the bearing has excellent transient response ability when subjected to impact load and magnetic field (applied by a controlled current). The self-sensing characteristic presents a monotonous decline trend with well linearity. This finding is significant because it suggests that the bearings based on the modified MREs are potentially capable of being used for vibration absorbers and sensor simultaneously. It's a valuable way to simplify the system structure and improve the response performance of vibration isolation.