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

航空航天、地面和海洋飞行器对更高的速度、更低的燃料消耗和更高的有效载荷能力的需求不断增加，这就要求这些飞行器使用的承载结构尽可能轻。然而，柔性轻质结构通常具有轻微的阻尼性，因此在不同的外部扰动下，很容易在其较低的固有频率附近被激励。这可能会导致过度振动，从而可能导致结构部件的疲劳失效或整个系统的灾难性失效。低频振动还会导致严重的结构噪声，为乘客和机组人员创造恶劣的环境，这可能会在反复长期暴露下导致严重的健康问题。由于传统被动结构的性能限制，以及全主动系统复杂的硬件和大功率的要求，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受到越来越多的关注，以设计出满足可靠性、性能和人体舒适性标准的低成本轻量化结构。磁流变材料和电流变材料是一种可以通过改变外加电场和磁场来快速、连续和可逆地控制其流变性的智能多功能材料。与电流变材料相比，磁流变材料可以提供明显更高的可控场相关屈服强度和屈服模数，因此成为最近研究的焦点。将分布式磁流变材料直接集成到柔性结构中，以及基于磁流变的自适应调谐减振器的开发，可以提供独特的机会来提供可变的刚度和阻尼性，从而极大地增强这些独特的智能材料在广泛频率范围内的控制权威。这项研究的目的是为具有磁流变材料的柔性自适应结构开发分析、设计优化和控制策略，以在较宽的频率范围内抑制噪声和振动。

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.