Analysis, Design Optimization and Control of Flexible Adaptive Structures to Attenuate Noise and Vibration

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The increased demand for higher speed, lower fuel consumption and higher payload capacity in aerospace, ground and marine vehicles requires the load carrying structures used in these vehicles to be as light as possible. However, flexible lightweight structures are typically lightly damped and thus can be easily excited near their lower natural frequencies under varying external disturbances. This may lead to excessive vibration, which may cause fatigue failure of structural components or catastrophic failure of whole systems. Vibrating at low frequencies can also cause severe structure-born-noise creating a harsh environment for passengers and crews, which may lead to severe health issues under repeated long-term exposure. Due to the performance limitation of traditional passive structures and also the complex hardware and large power requirements of fully active systems, adaptive structures comprising semi-active controllable Electrorheological (ER) and Magnetorhelogical (MR) fluids and elastomers have received growing interest as a viable technology to design the next generation of cost-effective lightweight structures which meet standards for reliability, performance and human comfort. MR and ER materials are types of smart multifunctional materials whose rheological properties can be controlled rapidly, continually and reversibly through variation of an external electric and magnetic field, respectively. MR materials can provide significantly higher controllable field-dependent yield strength and moduli compared with their ER counterparts and thus have been the focus of recent studies. Integration of distributed MR materials directly into flexible structures and the development of MR-based adaptive tuned vibration absorbers can offer unique opportunities to provide variable stiffness and damping properties which greatly enhance the control authority of these unique smart materials over a broad range of frequencies. The proposed research aims to develop analysis, design optimization and control strategies for flexible adaptive structures featuring MR materials to attenuate noise and vibration in a broad frequency range.