基于分布式动力吸振器的轻质结构减振降噪方法研究

To reduce pollution and energy consumption, lightweight design has become an important trend for the automotive industy. However, reducing structureal mass often leads to the degradation in the dynamic performance of structures, such as the noise, vibration and harshness (NVH) performance. It is known that the effects of traditional noise and vibration control approaches, including adding damping and stiffness to the original structure, are limited by their relatively large mass addition requirement. Inspired by the lightweight advantage demonstrated when using dynamic vibration absorbers (DVAs) to increase the transmission loss of aerospace structures, we propose to use distributed DVA to improve the noise and vibration performance of lightweight vehicle body structures and the sound quality. Compared to traditional methods, previous results have demonstrated that the DVA approach is relatively lightweight, especially for controlling the noise and vibration problems at low-mid frequencies. This study starts with the development of a coupled vibroacoustic model in reference to a simplified vehicle body shape. Different from existing models, the current model considers multiple flexible walls and random boundary conditions so as to address the potential needs of lightweight designs. Based on this model, the effects of the lightweight design on vehicle NVH performance are first analyzed. Then, the efficiency of controlling the NVH performance using the DVA approach, and the sensitivity of the DVA design parameters are studied in depth. Furthermore, the coupling effect among DVA parameters in terms of the NVH control efficiency, as well as the optimization methods and strategies of both passive and active DVA designs are investigated. in addition, the effectiveness and feasibility of both passive and active DVA approaches will be verified experimentally. The fundamental purpose of this study is to offer theoretical foundation and experimental support for the development of a novel, DVA based, lightweight NVH　control approach. The results of this study will also contribute to the methods and theory in analyzing vibroacoustic coupled problems consisting of complex shape and random boundary conditions.

以节能减排为目标的轻量化是汽车发展的重要趋势。而结构的轻量化往往会弱化车身振动噪声（NVH）等动态性能。传统的增加结构阻尼和刚度来提高NVH性能的措施，因附加质量大而在轻量化车身应用，特别是中低频应用中受到局限。受启发于动力减振器（DVA）在航空结构应用中体现的轻质优势，本项目提出应用分布式DVA控制轻量化车身振动噪声特性和声品质的概念。项目首先建立了包含多柔性板、任意边界条件的简化车身形体声固耦合分析模型。在此基础上，通过理论与实验手段，研究轻量化对车身结构声振性能的影响、分布式DVA减振降噪机理、DVA参数灵敏度、DVA参数间的耦合作用及主被动DVA参数优化策略，从而建立附加轻质DVA控制结构声振问题的理论体系和设计方法。本项研究不仅为轻质结构减振降噪控制技术的开发提供了新思路及相应理论基础和实验依据，而且也进一步完善了对具有复杂形状及任意边界条件的封闭腔体声固偶问题的分析方法和理论。

为实现对轻质结构减振降噪方法的研究，项目基于简化的长方体车身模型，建立了具有简支边界条件的单柔性板及双柔性板的声固耦合解析模型。根据Rayleigh-Ritz法和模态叠加法，展开并推导了具有任意边界条件的板结构声振耦合模型。同时根据复合材料层合板的弯曲波动方程导出了多层碳纤维板的传声损失计算解析模型。在理论模型基础上，对比研究了传统阻尼层与附加DVA控制方法对梁、板结构的减振降噪控制效能。根据“声学黑洞”的“声聚焦”理论，提出了将分布式DVA与“声学黑洞”结构相结合的轻质减振降噪措施。揭示了在附加质量一定下，这种将分布式DVA与阻尼层或具有“声学黑洞”结构的变厚度板相结合，能够显著提高对结构振动噪声控制的效果。从而为轻量化结构的振动噪声控制提供了新的思路和方法。