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

航空航天、地面和海上车辆对更高速度、更低油耗和更高有效载荷能力的需求不断增加，这就要求这些车辆中使用的承载结构尽可能轻。然而，柔性轻质结构通常是轻微阻尼的，因此在不同的外部干扰下，可以很容易地在其较低的固有频率附近被激发。这可能导致过度振动，从而可能导致结构部件的疲劳破坏或整个系统的灾难性破坏。低频振动还会产生严重的结构噪声，为乘客和机组人员创造恶劣的环境，在反复长期接触下可能导致严重的健康问题。由于传统被动结构的性能限制，以及全主动系统的复杂硬件和大功率要求，由半主动可控电流变（ER）和磁流变（MR）流体和弹性体组成的自适应结构作为一种可行的技术，设计出符合可靠性、性能和人体舒适度标准的低成本轻量级结构，受到越来越多的关注。MR材料和ER材料是一类智能多功能材料，它们的流变性能分别通过外部电场和磁场的变化进行快速、连续和可逆的控制。与ER材料相比，MR材料可以提供更高的可控场相关屈服强度和模量，因此成为最近研究的焦点。将分布式MR材料直接集成到柔性结构中以及基于MR的自适应调谐吸振器的开发可以提供独特的机会来提供可变刚度和阻尼特性，从而大大增强这些独特的智能材料在广泛频率范围内的控制权威。本研究旨在发展以磁流变材料为特征的柔性自适应结构的分析、设计优化和控制策略，以在宽频率范围内衰减噪声和振动。

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.