Characterization, Modeling, and Applications of Novel Magneto-Rheological Elastomers
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Magnetorheological elastomers (MREs) are an emerging branch within the smart materials field that consists of hard or soft magnetic particles embedded in a rubber compound. Current applications and research have been focused on changing the stiffness of these materials by applying an external magnetic field. Components of vibration absorbers and base isolation systems that employ this material have shown the capability of offering improved performance over conventional solutions. These particular applications use soft magnetic material; however, MRE materials containing hard magnetic filler materials (those that remain permanently magnetized) were the primary focus of this project and are referred to as H-MREs. When a magnetic field is applied perpendicularly to these particles, the filler particles generate a net torque and these samples can be used as a controlled actuator. Preliminary work has been conducted to characterize these H-MREs (since their properties are significantly different than “soft” MREs) and this work has shown their usefulness in engineering applications. However, unlike comparable smart materials such as piezoelectrics and electroactive polymers (EAP), additional modeling and experimentation needs to be conducted in order to develop usable models and better understand their behavior. The first portion of this paper focuses on developing experimental models to predict the behavior of H-MRE materials as cantilevered beam actuators for use in future applications. Two additional, newer applications for which H-MREs could be useful are energy harvesting and sensing. Sensors are utilized almost everywhere today as they are used to monitor the performance of a system (whether it is fluid flow, vibration measurements, etc.). Piezoelectric materials, those that respond to electric stimuli, and Galfenol, an engineered material similar to MREs, have been studied extensively for their application as self-sensing actuators. It is hypothesized that H-MREs could be used in a similar capacity by developing a way to monitor the displacement of the material using a magnetic circuit. Based on a similar principle, energy harvesting involves the conversion of one form of energy (kinetic, solar, etc.) into a more storable form. Previous research has been conducted using other smart materials in this capacity and it is also hypothesized that H-MREs could be used in a similar capacity by capturing energy from mechanical vibrations and storing it in the form of electrical energy/power using a specialized circuit and the same principles discussed above. The primary goal of the second portion of this project will be to determine the feasibility of using H-MREs in the capacity of energy harvesting and sensing technologies. This feasibility study includes the development of experiments to assess these capabilities and the implementation of the experiments for verification of the predicted behavior. Finally, much consideration is given to work that will need to be done in the future in order to fully understand the behavior of these materials and allow them to be implemented in future relevant applications.