thesis

Design and control of a vibration isolator using a biased magnetorheological elastomer

Abstract

The objective of this work is to explore the capability of a Semi-Active (SA) elastomer and control techniques in the area of shock and vibration isolation. Typical passive isolation methods have short comings in meeting competing objectives. A specific problem is isolating electronic packages mounted to military vehicle walls from shock. Often passive elastomer based isolators are used. The ideal solution for shock isolation is a soft lightly damped isolator. However a soft lightly damped isolator will cause excessive sway during normal driving conditions. Further, vehicle dynamics during normal driving conditions are typically in the range of a few hertz, presenting the possibility of a lightly damped soft system experiencing severe resonance. As a result most elastomer based isolators have significant damping, which decreases their ability to isolate shock. Active systems are able to theoretically reach a optimal compromise between shock isolation and sway, however for several reasons active systems are not practical. SA systems combine the benefits of passive systems, primarily cost and low actuator power input, with the capability of varying system parameters in real-time with performance indexes nearing that of active systems; This work investigates an interesting SA elastomer, a magnetorheological elastomer (MRE), that is able to change its properties with the application of a external magnetic field. Methods of controlling the field to achieve a desired response is discussed. Finally experimental data is presented of a MRE based device using a SA control scheme to isolate a payload from shock and vibration

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