Recent studies on plate-type metastructures have shown promising applications in low-frequency sound insulation, as they possess a low-frequency sound transmission loss (STL) that is considerably higher than that derived from the mass law. To design a plate-type metastructure for a sound insulation application, three problems are worth exploring: 1) how to predict efficiently the STL of the metastructure, 2) how to understand its unusual STL behavior, and 3) how to design its parameters to obtain a high STL at a target frequency and achieve a broad frequency band of high STL without increasing the mass. The purpose of this work is to address these problems by investigating a plate-type metastructure that is simply constructed using a periodic array of mass blocks attached to a thin host plate. For the first problem, a semi-analytical method is proposed for efficient prediction of normal, oblique, and diffuse STL based on fast retrieval of dynamic surface mass density using a considerably reduced structural finite element model and without having to include the acoustic field. This method is validated based on comparisons with an existing numerical method and reported experimental data. For the second problem, the mechanisms of unusual STL behavior are revealed by analyzing dynamic surface mass density as well as Bloch wave dispersion and Bloch modes. The third problem is addressed by conducting an elaborate parametric analysis that provides straightforward guidelines for adjusting structural parameters to tune the STL peak frequency as well as offering general guidelines for designing multiple parameters to achieve a broader frequency band of high diffuse STL with a given surface mass density. A design guideline for improving STL bandwidth is experimentally validated through measurements of two specimens designed and fabricated with identical surface mass densities. Because the considered plate-type metastructure is simple yet instructive, these investigations and findings are of fundamental and practical interest to the design of sound insulation metastructures.

板式元结构的最新研究显示了在低频隔音中的有希望的应用，因为它们具有的低频传声损耗（STL）远高于从质量定律得出的损耗。要设计用于隔音应用的平板型元结构，需要探索三个问题：1）如何有效地预测元结构的STL，2）如何理解其异常的STL行为，以及3）如何设计其参数以达到以下目的：在目标频率下获得高STL，并在不增加质量的情况下实现高STL的宽频带。这项工作的目的是通过研究一种平板型的元结构来解决这些问题，该结构是简单地使用附着在薄基板上的质量块的周期性阵列来构造的。对于第一个问题 提出了一种半分析方法，该方法基于动态表面质量密度的快速检索（使用显着减少的结构有限元模型，并且无需包括声场），可以有效地预测法向，倾斜和漫射STL。基于与现有数值方法的比较以及所报告的实验数据，对该方法进行了验证。对于第二个问题，通过分析动态表面质量密度以及Bloch波频散和Bloch模式揭示了异常STL行为的机制。第三个问题通过进行详细的参数分析得到解决，该分析提供了用于调整结构参数以调谐STL峰值频率的简单指南，并提供了设计多个参数以在给定表面质量下实现高扩散STL的较宽频带的通用指南。密度。通过测量以相同表面质量密度设计和制造的两个样品，通过实验验证了用于提高STL带宽的设计指南。因为所考虑的板式结构简单但具有启发性，所以这些研究和发现对于隔音结构的设计具有根本和实际的意义。通过测量以相同表面质量密度设计和制造的两个样品，通过实验验证了用于提高STL带宽的设计指南。因为所考虑的板式结构简单但具有启发性，所以这些研究和发现对于隔音结构的设计具有根本和实际的意义。通过测量以相同表面质量密度设计和制造的两个样品，通过实验验证了用于提高STL带宽的设计指南。因为所考虑的板式结构简单但具有启发性，所以这些研究和发现对于隔音结构的设计具有根本和实际的意义。