An approximation method for estimating the modal loss factors of a coupled structural-acoustical problem is proposed using the finite element method. This method provides a practical approach in terms of computational time and memory consumption. To validate our approach, we consider a coupled system in which the acoustical region is enclosed by a structural region, and both structural and acoustical regions are composed of various materials with individual damping characteristics. To obtain the modal loss factors, the modal strain and kinetic energy (MSKE) method is extended to the coupled problem by utilizing the sound pressure as a nodal unknown variable in the acoustical region. An air-filled PVC box was used as the test specimen. The measured and calculated frequency responses of the normalized sound pressure showed good agreement, verifying the reliability of the proposed method. Various damping parameters were tested for the sound-absorbing material inside the box to investigate the scope of the application of the proposed method. The discrepancy between the reference value and the proposed method is small considering fiberglass as a standard sound-absorbing material used in buildings. The proposed method also showed better management characteristics in terms of memory consumption and computational time.

提出了一种利用有限元方法估算结构声耦合问题模态损耗因子的近似方法。这种方法在计算时间和内存消耗方面提供了一种实用的方法。为了验证我们的方法，我们考虑一个耦合系统，在该系统中，声学区域被结构区域包围，而结构区域和声学区域均由具有各自阻尼特性的各种材料组成。为了获得模态损耗因子，通过利用声压作为声学区域中的节点未知变量，将模态应变和动能（MSKE）方法扩展到耦合问题。使用充气的PVC盒作为测试样品。归一化声压的测量和计算频率响应显示出良好的一致性，验证所提出方法的可靠性。测试箱内吸声材料的各种阻尼参数，以研究该方法的应用范围。考虑到玻璃纤维作为建筑物中使用的标准吸声材料，参考值与所提出的方法之间的差异很小。所提出的方法在内存消耗和计算时间方面也表现出更好的管理特性。