Abstract This paper is concerned with the prediction of the vibro-acoustic behaviour of rib-stiffened panels treated with multiple layers of porous materials. The acoustically treated rib-stiffened panels are assumed to be uniform and infinitely long in one direction (the longitudinal direction) but the cross-section can have an arbitrary and often complicated shape. Although the two-and-half dimensional structural finite element method (2.5D FEM) and the two-and-half dimensional acoustic boundary element method (2.5D BEM) may be combined to perform the vibro-acoustic prediction, the presence of the multiple layers of acoustic treatment often makes the prediction too time-consuming. More efficient methods are required for such structures and the aim of this paper is to propose such a method. The rib-stiffened panel and the fluid domain containing the incident and reflected sound waves are modelled using 2.5D FEM-BEM while the acoustic treatment layer and the fluid domain containing the transmitted sound waves are dealt with, approximately, using the transfer matrix method (TMM). The coupling of TMM and 2.5D FEM-BEM is formulated in detail. Since the acoustically treated panel is assumed to be flat and baffled, the 2.5D BEM is based on the Rayleigh integral in the wavenumber domain. Meanwhile, the TMM is based on a two-dimensional Fourier transform which implies that the porous layers also extend to cover the baffle; the validity of this assumption is explored. The accuracy and efficiency of the method is compared with a full 2.5D FE-BE method for a homogeneous plate with attached layers of absorbent material. It is shown that the method proposed in this paper can reduce calculation time by about a factor of three compared with the full 2.5D FE-BE method. The proposed method is then applied to study the sound transmission loss (STL) of a typical rib-stiffened panel from a train carriage which is acoustically treated with different porous material layers, demonstrating that the design of the acoustic treatment can have a significant effect on the STL of the panel.

中文翻译：

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结合2.5D FE-BE方法和TMM方法研究经过声学处理的加强筋板的振动声学

摘要 本文涉及对多层多孔材料处理的加强筋板的振动声学行为的预测。经过声学处理的加强筋板被假定为在一个方向（纵向）上均匀且无限长，但横截面可以具有任意且通常复杂的形状。虽然二维结构有限元法（2.5D FEM）和二维声学边界元法（2.5D BEM）可以结合起来进行振动声学预测，但存在多个声学处理层通常会使预测过于耗时。这种结构需要更有效的方法，本文的目的是提出这种方法。肋加强板和包含入射和反射声波的流体域使用 2.5D FEM-BEM 建模，而声学处理层和包含传输声波的流体域使用传递矩阵方法近似处理（ TMM）。详细制定了​​ TMM 和 2.5D FEM-BEM 的耦合。由于经过声学处理的面板被假定为平坦且有挡板的，因此 2.5D 边界元法基于波数域中的瑞利积分。同时，TMM 基于二维傅立叶变换，这意味着多孔层也延伸到覆盖挡板；探讨了这一假设的有效性。将该方法的准确性和效率与带有吸附材料层的均质板的完整 2.5D FE-BE 方法进行比较。结果表明，与完整的 2.5D FE-BE 方法相比，本文提出的方法可以将计算时间减少约 3 倍。然后将所提出的方法应用于研究来自火车车厢的典型加强筋板的声传输损失 (STL)，该板用不同的多孔材料层进行了声学处理，表明声学处理的设计可以对以下方面产生显着影响面板的 STL。