Active tuning of vibration and noise by the optimal design of acoustic metamaterial structures

机敏或智能材料由于其对外界力学环境变化的敏感性和主动响应的能力而被广泛应用于结构振动主动控制中。因此，这类智能材料具有很大的潜力，主动调整的声学超材料的带隙特性。基于这一事实，如果能够利用主动结构优化设计将智能材料嵌入声学超材料结构中，则可以将声学超材料的被动隔声能力与智能材料的主动控制性能有效结合。所提出的新型有源超材料结构将具有以下两个功能：（i）超材料结构的单元格的刚度和质量可以通过控制算法的设计来主动调谐，以主动控制频率带隙的宽度和位置，以及（ii）可以通过使用声学超材料的带隙特性来抑制频率带隙中的振动和噪声，而对于通频带内的振动和噪声，则可以通过智能材料的主动控制能力加以抑制。因此，振动和噪声可以减少在整个频率范围内通过所提出的新的策略。 本计画将提出并设计具有主动控制功能之新型超材料声学结构。在新的系统中，压电粗纤维复合材料（MFC）将被用作主动控制器。本文将在充分考虑MFC材料各向异性和机电耦合特性的基础上，对MFC的振动带隙特性、噪声隔离能力和主动控制优化设计进行系统的理论、数值和实验研究。该研究将声超材料的被动控制性能和压电材料的主动控制能力有效地结合起来，在所需频率范围内抑制振动和噪声，为结构振动控制、弹性波调谐以及新型降噪材料和结构的开发提供了新的思路和方法。因此，本课题对于声学超材料及其结构在减振降噪方面的创新工程应用具有重要的意义。 该项目是中德双方的合作项目。两个团队多年来一直保持着密切的合作。通过这一联合项目，应继续并加强它们以前的合作。两个团队将在拟议的项目上合作，联合收割机结合各自的研究优势，并促进参与的德国和中国年轻科学家。

Smart or intelligent materials are widely used in the structural active vibration control because they have the sensitivity to external mechanical environment changes and the ability to actively respond. Therefore, these kinds of intelligent materials have a great potential to actively tune the band-gap properties of the acoustic metamaterials. Based on this fact, if the intelligent materials can be embedded into the acoustic metamaterial structures by using the active structural optimization design, the passive acoustic insulation ability of the acoustic metamaterials can be effectively combined with the active control performance of the intelligent materials. The proposed novel active metamaterial structures will possess the following two functions: (i) the stiffness and the mass of the unit-cell of the metamaterial structures can be actively tuned by the design of the control algorithm to actively control the widths and locations of the frequency band-gaps, and (ii) the vibration and noise in the frequency band-gaps can be suppressed by using the band-gap property of the acoustic metamaterials, while for the vibration and noise in the frequency pass-bands, they can be suppressed by the active control ability of the intelligent materials. Thus, the vibration and the noise can be reduced in the full frequency range via this proposed novel strategy. In this project, novel acoustic metamaterial structures with active control functions will be proposed and designed. In the novel systems, the piezoelectric macro-fiber composites (MFC) will be adopted as an active controller. Taking into account the effects of the material anisotropy and the electromechanical coupling properties of the MFC, theoretical, numerical and experimental investigations on the vibration band-gap property, the noise isolation ability and the active control optimization design will be systematically conducted. In the investigations, the passive control performance of the acoustic metamaterials and the active control ability of the piezoelectric materials will be effectively combined to suppress the vibration and the noise levels in the desired frequency range, which will provide a novel idea and a new approach for the structural vibration control, the elastic wave tuning and the development of novel noise reduction materials and structures. Thus, the project has a great importance and significance in innovative engineering applications of the acoustic metamaterials and structures for the vibration and noise reduction. This proposed project is a cooperation project by the German and the Chinese applicants. Both teams have a close cooperation since several years. Through this joint project, their previous cooperation should be pursued and strengthened. Both teams will work together on the proposed project, combine their individual research strengths and promote participating young German and Chinese scientists.