基于声学超材料的高刚度高阻尼结构低频减振设计
发布时间：2018-12-08 14:01
【摘要】：随着飞行器、舰船、高速列车等工程装备不断向轻质、高速、重载等方向发展,复合材料、超轻多孔材料、蜂窝材料兼具轻质、高比强度、高比刚度等优良特性而广泛应用于实际装备中。结构的轻质和高刚度特性导致其环境适应性差,容易引发严重的振动噪声问题,减振降噪需求迫切。针对轻质、高刚度结构的振动噪声问题,一方面需要引入阻尼机理对载荷引起的振动进行有效抑制,另一方面仍然需要保证结构高刚度特性满足承受外界载荷需求。通常情况下,阻尼特性的加强会降低结构的刚度特性。因此,在工程减振降噪领域,刚度与阻尼的矛盾已经成为结构设计中亟待解决的关键瓶颈问题。本文以实现结构高刚度、高阻尼特性为目标,选取典型工程梁框架支撑结构为对象,对结构进行高刚度、高阻尼设计,其中重点研究结构的低频高阻尼特性。本文以超材料理论为基础,利用超材料所具有的弹性波低频带隙特性,设计手性超材料和质量放大型超材料结构阻尼单元,嵌入梁框架结构中,从而实现结构对低频稳态载荷和冲击载荷的高效抑制。论文的主要研究内容和研究结论如下:1.建立了二维人工周期结构带隙特性和波传播方向性的计算方法。对两种典型的手性超材料带隙特性和波传播方向进行了深入分析,结合带隙起止频率处的元胞振型,分析带隙产生原因。对关键参数进行参数扫描,研究了手性超材料的拓扑结构形式对带隙位置、宽度的影响规律。2.研究了一种质量放大型超材料带隙特性。从带隙起止频率处振型和带隙内反共振点能量分布情况两个角度,分析了质量放大带隙机理和局域共振带隙机理,并研究了质量放大型超材料的负刚度、高阻尼特性,最后对关键参数对带隙的影响规律进行了分析。3.对手性超材料和质量放大超材料进行阻尼结构设计,在稳态载荷和瞬态冲击两种激励方式下实现了对工程梁框架支撑结构振动的控制,并进行实验验证。针对特定敏感频率(一阶固有频率)下的振动,优化结构形式,实现了一阶固有频率处极大衰减的抑振效果。总之,本文以高刚度、高阻尼结构的工程需求为牵引,以实现低频减振设计为目标,研究了两种新型声学超材料带隙产生机理,带隙特性,并对两种声学超材料进行结构高阻尼设计,实现了对梁框架结构的低频振动控制,并通过实验得到了验证。本文的研究工作为高刚度、高阻尼结构设计进行了有益的探索,对实际工程结构中的应用具有一定指导作用。
[Abstract]:As aircraft, ships, high-speed trains and other engineering equipment continue to develop in the direction of light, high speed and heavy load, composite materials, ultra-light porous materials, honeycomb materials have both light weight and high specific strength. High specific stiffness and other excellent characteristics are widely used in practical equipment. The light weight and high stiffness of the structure lead to its poor adaptability to the environment, which can easily lead to serious vibration and noise problems, so it is urgent to reduce vibration and noise. For the vibration and noise problem of light and high stiffness structures, on the one hand, damping mechanism should be introduced to effectively suppress the vibration caused by loads, on the other hand, it is still necessary to ensure that the high stiffness characteristics of the structures can meet the external load requirements. In general, the strengthening of damping characteristics will reduce the stiffness characteristics of the structure. Therefore, in the field of engineering vibration and noise reduction, the contradiction between stiffness and damping has become the key bottleneck in structural design. The aim of this paper is to realize the high stiffness and damping characteristics of the structure and select the typical beam frame braced structure as the object to design the structure with high stiffness and high damping. The emphasis is on the low frequency and high damping characteristics of the structure. Based on the theory of metamaterials, the damping elements of chiral supermaterials and mass-released large supermaterials are designed and embedded into the beam frame structure by using the elastic wave low frequency band gap characteristic of the metamaterials. Thus, the structure can suppress the low frequency steady load and impact load efficiently. The main research contents and conclusions are as follows: 1. A method for calculating the band gap characteristics and wave propagation directivity of two dimensional artificial periodic structures is established. The band gap characteristics and wave propagation direction of two typical chiral metamaterials are analyzed in depth. The causes of band gap are analyzed in combination with the cell mode at the frequency of band gap initiation and stop. The influence of the topological structure of chiral supermaterial on the position and width of band gap was studied by scanning the key parameters. 2. The band-gap characteristics of a mass amplifier supermaterial are studied. The mass amplification band-gap mechanism and the local resonance band-gap mechanism are analyzed from the view of the mode shape at the starting and stopping frequency of the bandgap and the energy distribution of the antiresonance point in the band-gap. The negative stiffness and high damping characteristics of the mass-discharge supermaterial are studied. Finally, the influence of key parameters on the band gap is analyzed. The damping structure is designed by chiral supermaterial and mass amplification supermaterial. The vibration control of the braced structure of engineering beam frame is realized under the two excitation modes of steady load and transient shock, and the experimental results are verified. According to the vibration of certain sensitive frequency (first order natural frequency), the structure form is optimized, and the vibration suppression effect of the maximum attenuation at the first order natural frequency is realized. In a word, aiming at the engineering demand of high stiffness and high damping structure, and aiming at the design of low frequency vibration absorption, this paper studies the band-gap generation mechanism and band gap characteristics of two new acoustic supermaterials. Two kinds of acoustic supermaterials are designed with high damping, and the low frequency vibration control of beam frame structure is realized, which is verified by experiments. The research work in this paper is beneficial to the design of high stiffness and high damping structures, and has a certain guiding effect on the application of practical engineering structures.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34
本文编号：2368480
[Abstract]:As aircraft, ships, high-speed trains and other engineering equipment continue to develop in the direction of light, high speed and heavy load, composite materials, ultra-light porous materials, honeycomb materials have both light weight and high specific strength. High specific stiffness and other excellent characteristics are widely used in practical equipment. The light weight and high stiffness of the structure lead to its poor adaptability to the environment, which can easily lead to serious vibration and noise problems, so it is urgent to reduce vibration and noise. For the vibration and noise problem of light and high stiffness structures, on the one hand, damping mechanism should be introduced to effectively suppress the vibration caused by loads, on the other hand, it is still necessary to ensure that the high stiffness characteristics of the structures can meet the external load requirements. In general, the strengthening of damping characteristics will reduce the stiffness characteristics of the structure. Therefore, in the field of engineering vibration and noise reduction, the contradiction between stiffness and damping has become the key bottleneck in structural design. The aim of this paper is to realize the high stiffness and damping characteristics of the structure and select the typical beam frame braced structure as the object to design the structure with high stiffness and high damping. The emphasis is on the low frequency and high damping characteristics of the structure. Based on the theory of metamaterials, the damping elements of chiral supermaterials and mass-released large supermaterials are designed and embedded into the beam frame structure by using the elastic wave low frequency band gap characteristic of the metamaterials. Thus, the structure can suppress the low frequency steady load and impact load efficiently. The main research contents and conclusions are as follows: 1. A method for calculating the band gap characteristics and wave propagation directivity of two dimensional artificial periodic structures is established. The band gap characteristics and wave propagation direction of two typical chiral metamaterials are analyzed in depth. The causes of band gap are analyzed in combination with the cell mode at the frequency of band gap initiation and stop. The influence of the topological structure of chiral supermaterial on the position and width of band gap was studied by scanning the key parameters. 2. The band-gap characteristics of a mass amplifier supermaterial are studied. The mass amplification band-gap mechanism and the local resonance band-gap mechanism are analyzed from the view of the mode shape at the starting and stopping frequency of the bandgap and the energy distribution of the antiresonance point in the band-gap. The negative stiffness and high damping characteristics of the mass-discharge supermaterial are studied. Finally, the influence of key parameters on the band gap is analyzed. The damping structure is designed by chiral supermaterial and mass amplification supermaterial. The vibration control of the braced structure of engineering beam frame is realized under the two excitation modes of steady load and transient shock, and the experimental results are verified. According to the vibration of certain sensitive frequency (first order natural frequency), the structure form is optimized, and the vibration suppression effect of the maximum attenuation at the first order natural frequency is realized. In a word, aiming at the engineering demand of high stiffness and high damping structure, and aiming at the design of low frequency vibration absorption, this paper studies the band-gap generation mechanism and band gap characteristics of two new acoustic supermaterials. Two kinds of acoustic supermaterials are designed with high damping, and the low frequency vibration control of beam frame structure is realized, which is verified by experiments. The research work in this paper is beneficial to the design of high stiffness and high damping structures, and has a certain guiding effect on the application of practical engineering structures.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34
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