【作者】 谢芳；

【导师】 肖柏勋； 杨河林；

【作者基本信息】 长江大学 ， 地质工程， 2017， 硕士

【摘要】 随着现代生活节奏快速化,噪音在某种程度上来说是不可避免,也极其有害的。一直以来,由于低频噪声的特殊性,使其拥有很强的穿透力,导致了传统材料很难有效的隔离或吸收低频噪声,这也使其成为环境污染的重要原因之一。因此,轻质超薄的低频隔声材料一直是隔声、降噪领域的研究重点。近年来,声学超材料作为一种单元结构为亚波长的人工声学材料,具有自然材料难以具有的独特属性,这使其理论和应用研究受到了普遍关注。而基于声学超材料的各种声学器件的研究和设计,如减振降噪结构也已成为研究的热点问题。可以说,薄膜型声学超材料的出现,弥补了传统的线性隔声材料应对低频噪声问题上的缺陷,其在实现轻质低频隔声方面具有明显优势。本文系统的由低频降噪方面的降噪机理出发,研究设计了一种薄膜型声波超介质材料,以期更好地应用于实际,本文具体的研究内容如下:(1)由声传播波动方程理论入手,讨论分析了声波在隔声结构表面的反射、透射以及吸收系数,从理论上分析了隔声原理基础,并且给出了隔声性能的评价指标。以结构力学能量理论为基础,分析薄膜结构形变状态下应变能的分布,介绍了薄膜型材料的隔声特性,为薄膜声学超材料隔声机理的分析提供了基础。(2)主要介绍了薄膜型声学超材料隔声量计算的有限元仿真方法。根据薄膜型声学超材料的理论模型,基于有限元分析方法和多物理场有限元分析软件COMSOL,建立了超材料的声一固耦合模型。分析了薄膜声学超材料在不同频率(100Hz-1200Hz)的声源激励下的隔声效果,证明了超材料在低频率范围内降噪的有效性。(3)基于模型的基础,讨论改变超材料结构参数对超材料的吸声系数的影响。通过对结构参数和质量块结构的修改,得到降噪效果更明显的模型结构,为之后生产应用化提供更优质的模型。并提供了制作样品结构进行低频降噪隔声效果的实验方法,可进一步验证模型材料的有效性和优质性。更多还原

【Abstract】 With the rapid pace of modern life,noise to some extent is inevitable and yet extremely harmful.In particular,due to its characteristic properties,thelow-frequency noise possesseshigh penetrating power,which makes it difficult for traditional materials to effectively isolate or absorb low-frequency noise,and hence it becomes a pernicious form of environmental pollution.To reduce the harm of low-frequency noise,new materials are desired.To this end,the lightweight ultra-thin low-frequency sound insulation materialshave been the research focus in the field of sound insulation and noise reduction.Acoustics metamaterials regarded as a kind of artificial acoustics material with sub-wavelength structure have characteristic properties superior to the natural materials,triggering relevant theoretical and applied in recent years.While,the research and design of various acoustic devices based on acoustic metamaterials,such as vibration and noise reduction structure,have become research focus.It can be said that the emergence of thin film-type acoustic metamaterials has made up for the shortcomings of traditional linear sound insulation materials on dealing with low-frequency noise problems,and they have obvious advantages on lightweight low-frequency sound insulation.In this paper,the mechanism of low frequency noise reduction has been studied systematically,and a kind of thin film type acoustic metamaterials expected to be well applied in practice has been designed.The research contents are as follows:(1)Starting from the theory of acoustic propagation,the reflection,transmission and absorption coefficients of sound waves on the surface of sound insulation are analyzed.The mechanism of the sound insulation is analyzed theoretically,and the evaluation index of sound insulation performance is given.Based on the principle of energy in structural mechanics,the distribution of strain energy in the thin film structure under deformation is analyzed,and the sound insulation properties of the film materials are stated,which provides the basis for the analysis of the sound insulation mechanism of the thin film acoustic materials.(2)The finite element simulation method for the calculation of sound insulation of thin film acoustic material is introduced.Based on the theoretical model of thin film acoustic metamaterials and the finite element method,the acoustic-solid coupled model of metamaterials is established with the aid of the commercial finite element software COMSOL.The sound insulation performance of thin film acoustic material under the stimulation from acoustic source at different frequencies(100Hz-1200Hz)is analyzed,and the effectiveness of metamaterials on noise reduction in low frequency range is validated.(3)Based on the model,the effect of the structure parameters on the coefficient of sound absorption of metamaterials is discussed.Through the modification of the structure parameters and the structure of the mass block,the model structure with higher performance is obtained.And experimental method on testing the effectiveness of low frequency noise reduction and sound insulation through making sample structure is provided,which can further validate the effectiveness of the model material.更多还原