【作者】 张强；

【导师】 程树良；

【作者基本信息】 燕山大学 ， 力学， 2025， 硕士

【摘要】 随着工业技术的快速发展,振动噪声已成为制约高端装备性能、人居环境质量的关键瓶颈问题。人们发现人工合成的周期结构能够很有效的减少或是控制工业噪音,在此基础上发展起来的声学超材料便成了人们重点研究的对象之一。本文以实现单一超宽带隙与低频段高覆盖率带隙为目的,结合布洛赫定理分别设计了两类声学超材料。首先,本文设计了宽频星型超材料和低频靶心超材料,通过计算二者能带结构发现在拟定的频率范围内均具有良好的带隙特征。其次,为了分析弹性波通过结构介质所表现出的传播特性,采用相位常数面图、群速度和相速度模拟,发现带隙启闭时,弹性波传播会存在各向异性,呈现出一定的方向性和区域性。探究能带的启闭机理,对结构的振动模态进行分析,发现局域共振是导致带隙启闭的关键因素。最后,通过对两类结构进行有限周期情况下的传输损耗计算和应力响应分析,证明了其能带结构计算的正确性,同时也反应了周期结构对弹性波的抑制能力。通过改变两类结构几何参数和材料组合,发现带隙范围具有起始频率降低的趋势,实现了对能带范围的宏观调控。本文所提出的两类新型超材料,分别实现了宽频段带隙集中、低频带隙带宽增大和覆盖率高的目标,且能够根据实际需求对带隙范围进行调控。同时,二者在带隙范围内具有良好的降噪减振效果,该研究对设计宽低频带隙的周期性声学超材料结构提供了参考方案。更多还原

【Abstract】 With the rapid development of industrial technology,vibration noise has become a key bottleneck limiting the performance of high-end equipment and the quality of human environment.It has been found that synthetic periodic structures can effectively reduce or control industrial noise,and acoustic metamaterials developed on this basis have become one of the key research objects.In this paper,two types of acoustic metamaterials are designed to realize a single ultra-wide bandgap and a low-frequency bandgap with high coverage in combination with Bloch’s theorem.Firstly,broadband star metamaterials and low-frequency bull’s-eye metamaterials are designed in this paper,and the energy band structures of both are found to have good bandgap characteristics in the proposed frequency range by calculating their energy band structures.Secondly,in order to analyze the propagation characteristics of elastic waves through the structured medium,phase constant surface map,group velocity and phase velocity simulations are used,and it is found that the elastic wave propagation is anisotropic and shows certain directionality and regionality when the bandgap is opened and closed.To explore the mechanism of energy band opening and closing,the vibration modes of the structures are analyzed,and it is found that the local resonance is the key factor leading to the bandgap opening and closing.Finally,by simulating the transmission loss and analyzing the stress response of the two types of structures in the finite period case,the correctness of their energy band structure calculations is proved,and the suppression ability of the periodic structures to elastic waves is also responded.By changing the geometrical parameters and material combinations of the two types of structures,it is found that the bandgap range has a tendency to actually decrease in frequency,which realizes the macroscopic regulation of the energy band range.The two new types of metamaterials proposed in this paper realize the goals of wide bandgap concentration,increased bandwidth and high coverage of low-frequency bandgap,respectively,and can regulate the bandgap range according to practical needs.At the same time,the two have good noise reduction and vibration damping effects in the bandgap range,and the study provides a reference program for designing periodic acoustic metamaterial structures with wide-frequency and low-frequency bandgaps.更多还原