Active sound irradiation reduction into cavities

声音进入诸如车辆或飞机的空腔的传输通常是通过平面结构，例如飞机的外壳。对于平面结构的声辐射的描述，在技术文献中可获得广泛的知识，其描述了到声学远场中的能量传输。因此，很大一部分的室内振动结构的声辐射的主动减少的方法是基于这些发现。存在许多分析、数值和实验研究。然而，事实上，结构振动与内部声学介质相互作用。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。例如，这可以通过模态耦合理论以解耦的声学特征向量和结构模态的形式来实现。申请人先前的工作表明，可以通过与频率无关的声辐射模式来估计声势能。一个控制器，其目的是在抑制的声学势能，必须考虑只有一个模式形状每个声音辐射模式的所有频率，不再是一个模式每个离散的频率步长。这一事实使得利用结构传感器技术进行全局声控制成为可能。然而，目前还不清楚参数，如空腔尺寸，结构质量和刚度，以及结构各向异性影响声辐射模式的程度。同样无法解释的是不规则的空腔几何形状（如底部的圆柱体）对声辐射模式的频率依赖性的影响。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.