声学黑洞结构中Lamb波传播特性的理论和实验研究

The acoustic black holes structure has attracted a lot of attention due to its obvious damping, noise reduction and other effects in the engineering structure. The project combines the concept of traditional phononic crystals with acoustic black hole to construct a local resonant periodic structure based on acoustic black holes. Detailed theoretical and experimental studies on the propagation of elastic guided wave Lamb waves are carried out. Based on the three-dimensional finite element method, the energy band structure of phononic crystals based on acoustic black hole structure is calculated and the influence of lattice constants on the dispersion of Lamb wave is analyzed. The theory of topological energy band of phononic crystals based on acoustic black hole structure is further developed to design acoustic artificial structures for Lamb wave propagation control. The topological energy band structure is also designed to realize the acoustic topological insulator based on acoustic black hole structure. The optical interference system is established to realize the optical full field dynamic imaging of the Lamb wave propagation in the phononic crystals.

声黑洞结构由于其在工程结构中具有明显的减振、降噪等作用引起了广泛关注。本项目将传统声子晶体概念与声黑洞结构相结合，构建基于声黑洞的局域共振型周期性结构，针对弹性导波Lamb波在其中的传播进行详细的理论和实验研究。基于三维有限元方法计算基于声黑洞结构的声子晶体的能带结构，分析晶格常数对Lamb波色散关系的影响；进一步发展基于声黑洞结构的声子晶体的拓扑能带理论，设计精确用于Lamb波传播控制的声学人工结构；并设计拓扑能带结构，最终实现基于声黑洞结构的声学拓扑绝缘体。建立光学干涉系统，实现对周期性结构中Lamb波传播过程的光学全场动态成像。

声学黑洞结构由于其在工程结构中具有明显的减振、降噪作用引起了广泛关注。Lamb波由于其多模态、传输能耗低等优点在材料缺陷检测和性能评估中得到了广泛的应用。本项目结合声学黑洞结构和Lamb波的优势，分别从理论计算，数值模拟和实验研究三个方面对弹性导波Lamb波在声学黑洞结构中的传播进行了深入的研究。.基于几何声学近似理论，并结合Rayleigh-Lamb方程对Lamb波在厚度变化满足幂律分布的声黑洞结构中Lamb波的传播特性；针对现有的二维有限元模型研究无法得到声场的整体分布的局限性，基于三维有限元方法对声学黑洞结构中Lamb波的传播进行了数值模拟，得到Lamb波在其中传播的声场分布，研究中发现在声黑洞结构中声波向厚度减小区域传播时，波束宽度逐渐变窄，同时振幅逐渐增大，声波在其中的传播速度逐渐减小；同时基于能量守恒原理计算并验证了声黑洞结构对Lamb波的局域作用。打破传统稳态坐标系中的研究方式，引入旋转坐标系，对旋转条件下的声学黑洞结构的特性进行了研究。研究成果对声黑洞结构在减震降噪领域的应用和利用其实现对声波传播的有效操控等具有重要意义。