Active sound irradiation reduction into cavities

声音进入车辆或飞机等空腔的传输通常是通过飞机结构，例如飞机的外壳。对于平面结构的声辐射的描述，在技术文献中有广泛的知识，它描述了进入声远场的能量传输。因此，主动减少内部振动结构声辐射的大部分方法都是基于这些发现。存在大量的分析、数值和实验研究。但实际上，结构振动与内部声介质相互作用。一种能量交换发生了。为了降低整个内部的声压，必须考虑内部动力学。这可以通过模态耦合理论来实现，例如，以解耦的声学特征向量和结构模态的形式。申请者以前的工作表明，可以通过频率无关的声辐射模式来估计声势能。以抑制声势能为目标的控制器，在所有频率下每个声辐射模态只考虑一个模态，而不再是每个离散频率步长考虑一个模态。这一事实使结构传感器技术的全局声学控制成为可能。然而，腔体尺寸、结构质量和刚度以及结构各向异性等参数对声辐射模式的影响程度尚不清楚。同样无法解释的是不规则腔体几何形状（例如带底的圆柱体）对声辐射模态频率依赖性的影响。通过分析和数值方法以及实验验证系统地阐明这些关系是计划工作的目标。

The transmission of sound into cavities such as vehicles or aircraft is usually through plane structures, e.g. the outer skin of an airplane. For the description of the sound radiation of planar structures, extensive knowledge is available in the technical literature, which describes an energy transport into the acoustic far field. Therefore, a large part of the approaches for the active reduction of sound radiation of vibrating structures in interiors is based on these findings. Numerous analytical, numerical and experimental investigations exist. In fact, however, the structural vibration interacts with the internal acoustic medium. An energy exchange takes place. In order to reduce the sound pressures in the entire interior, the interior dynamics must be considered. This can be realized, for example, by modal coupling theory in the form of decoupled acoustic eigenvectors and structural modes. The previous work of the applicants shows that it is possible to estimate the acoustic potential energy by means of frequency independent sound radiation modes. A controller, which aims at the suppression of the acoustic potential energy, has to consider only one mode shape per sound radiation mode for all frequencies and no longer one mode per discrete frequency step. This fact puts a global acoustic control with structural sensor technology into the field of the feasible. However, it is unclear to what extent parameters such as cavity dimension, structural mass and stiffness, and structural anisotropy influence the sound radiation modes. Also unexplained is the influence of irregular cavity geometries (e.g. cylinder with bottom) on the frequency dependence of the sound radiation modes.The systematic elucidation of these relationships by analytical and numerical methods as well as experimental validation are goals of the planned work.