水下粘弹性声子晶体结构带隙特性和设计理论研究

Focusing on the major strategic needs of Hainan Province in developing ocean engineering and that of the state in safeguarding maritime rights and interests, the issue of the suppression of vibration and sound of underwater marine structures is addressed. This subject introduces the concept of band gaps into the field of underwater sound and vibration reduction, aiming to realize the design exhibiting low frequency and ultra-wide band gap properties via the research on band gap characteristics of underwater phononic crystals. Firstly, taking into account the damping characteristics of viscoelastic materials and the fluid-structure interaction, the numerical model for investigating the band gap properties of underwater viscoleastic phononic crystals is established by employing the Bloch wave expansion method and the Galerkin method. Secondly, the research of mechanisms on band gaps is carried out. The influences of viscoelastic damping and fluid-structure interaction on location of band gaps, range of band gaps, generation mechanisms, attenuation factor and degree of attenuation anisotropy are studied. The analysis demonstrates the efficiency of the application of underwater viscoelastic phononic crystals to reduce underwater sound and vibration. Thirdly, this object presents a parametric study to reveal the effects of geometric parameters, material properties, topological pattern on band gap properties. Based on the parametric study, the topological configuration exhibiting low frequency and wide band gap properties is expected to be designed. Finally, the calculation of vibration transmission loss of finite phononic crystals and the conduction of the test of sound absorption in acoustic tube verify the band gap properties of underwater phononic crystals analytically and experimentally, respectively. The research results will lay a theoretical foundation for the design and application of ship and marine structures to reduce vibration and sound.

围绕海南省发展海洋工程和国家维护海上权益的战略需求，聚焦水下工程结构的减振降噪问题，申请人将带隙特性引入到抑制水下振动和噪声领域中，旨在通过研究水下声子晶体结构的带隙特性，实现具备低频宽带的水下吸声结构。首先，考虑流固耦合效应和粘弹性材料的阻尼特性，基于Bloch波函数和伽辽金方法建立求解水下粘弹性声子晶体结构带隙特性的计算模型；然后，开展关于带隙特性的机理研究，分析粘弹性阻尼和流固耦合对带隙位置、范围、生成机制、衰减因子、衰减各向异性的影响，揭示水下粘弹性声子晶体结构用于吸声降噪的作用机理；再次，开展参数化研究，分析几何参数、材料参数、拓扑型式对带隙特性的影响，设计具备低频宽带特性的水下声子晶体结构的拓扑构型。最后，通过有限声子晶体结构的振动传递损失结果以及声管试验在理论和试验方面分别验证水下粘弹性声子晶体结构的带隙特性。研究成果将为新型船舶与海洋结构物减振降噪设计与应用奠定理论基础。

聚焦水下工程结构的减振降噪问题，本项目将带隙特性引入到抑制水下振动和噪声领域，把减振降噪问题转化为波动传播和衰减调控问题，目标是实现具备低频多禁带的声子晶体结构。基于以上研究思路，本项目以复杂梁板周期结构为研究对象，开展了以下研究：1. 考虑流固耦合效应和粘弹性材料阻尼特性，引入功能梯度材料和压电超材料的可调属性，利用伽辽金方法、Bloch波函数展开、能量法则和Maxwell阻尼模型，提出了求解水下声子晶体板、粘弹性开孔声子晶体结构、惯性放大功能梯度梁和压电超材料梁等复波矢能带的数值计算模型。2. 分析了外部半无限大重流体加载效应、粘弹性阻尼、材料梯度分布、外部分流电路等对弹性波带隙位置、范围、衰减能力和衰减方向等的影响，完成了水下声子晶体带隙调控机理研究以及为主动可调带隙机制发展奠定了基础。3. 基于前述参数化分析，分别以压电片布局、电路参数和材料参数等为设计变量，完成了最大化低频段和宽带带隙平均衰减系数的优化设计；进一步地，利用人工神经网络模型初步完成了一维超材料梁弯曲波带隙的按需设计。4. 通过空气和水下有限声子晶体结构的振动传递损失结果验证了声子晶体结构的带隙特性，为水下声子晶体实际应用奠定了基础。本项目研究内容进展顺利，在水下声子晶体带隙计算与设计以及可调带隙应用方面取得了一定研究成果，资助期间发表基金标注的SCI期刊论文9篇。