声腔结构中频声振耦合建模研究及不确定性影响分析

发布时间：2018-03-09 03:08

本文选题：声腔　切入点：中频　出处：《东南大学》2017年博士论文　论文类型：学位论文

【摘要】：众所周知,任何复杂的机械系统都可以被视为由诸多不同子系统组合而成。由于系统的各个组成部分在制造材料、结构和尺寸方面的差异性,就导致了系统局部结构间动态特性的差异性,从而使得整个系统结构的振动在相当广的频率区间内表现出由模态密度较低子结构产生的长波变形和由模态密度较高子结构产生的短波变形同时并存的复杂混合振动特征。学术界因此将系统振动中局部低频振动与局部高频振动同时并存的复杂振动情况笼统的定义为系统的"中频振动"。而在此频段内,传统的有限元法、边界元法和统计能量分析法均在一定程度上丧失了计算的准确性及有效性。因此,复杂组合系统中频振动问题一直是学术界主要研究课题之一。由于复杂组合系统的子系统在制造、装配和测量等过程中不可避免地存在着误差,正是由于这些微小误差的存在而引起了系统的不确定性。在大多数情况下,这些不确定性数值较小。但是,随着频率的升高,系统的动态特性对参数的变化越来越敏感,不确定性对系统的整体动态特性影响也逐渐增大;此外,许多不确定性因素耦合在一起,可能导致实际声振耦合系统响应产生较大偏差,甚至出现反相现象。目前,对不确定性的建模研究主要还是局限于系统的非参数不确定性,而针对模型不确定性对系统响应的影响及量化研究较少。此外,不确定数值分析与优化方法的研究主要集中在不确定结构领域,其在声-固耦合系统领域的研究尚处于起步阶段。本文在江苏省科技支持计划项目(BE2014133)、江苏省产学研前瞻性联合研究项目(BY2014127-001)及东南大学水声信号处理教育部重点实验室开放性基金项目(UASP1301)的资助下,针对声腔结构的典型中频声-振问题及不确定性因素对声腔结构动力学响应分析进行了深入研究,并取得了一些有意义的结论。该研究结果对声腔结构及类声腔结构的中频声-振设计及腔内噪声的控制有重要的理论意义及实用价值。本文的主要研究内容及创新点如下:(1)推导了混合模型的建立过程及求解过程,详细介绍了 Hybrid finite element-statistic energy analysis method(混合 FE-SEA 方法)的理论原理,并对混合 FE-SEA 方法的使用前提假设做了说明。以典型中频框架-板系统为研究对象,建立了混合FE-SEA模型。通过引入参数不确定性分别研究了结构动态特性不确定性、连接边界不确定性在确定激励下对混合模型计算结果的影响,得出了一些有意义的结论。(2)针对具有不同边界条件的声腔结构的内损耗因子和耦合损耗因子不易获取等问题,提出了一种新的通过实验测量来确定各子系统的内损耗因子及子系统间的耦合损耗因子计算方法。研究了具有不同边界条件的矩形声腔损耗因子的获取方法,该方法通过测量系统子结构总损耗因子以及子系统间的能量比,可直接同时计算内损耗因子和耦合损耗因子。该方法无需做任何条件简化,计算结果能更全面反应子系统的损耗特性。(3)基于中频混合理论建立了带孔隙隔声结构传递损失的Diffuse acoustic field-Semi-infinite field(DAF-SIF)预测模型,研究了带孔隙隔声结构的声传递特性,并与解析结果进行了对比分析。研究了不确定性对带孔隙板隔声性能的影响特性,分析了结构在不同边界条件、不同开孔率及是否密封条件下的声传递特性,为工程上隔声设计及噪声治理提供理论基础。(4)提出了一种基于随机矩阵理论的建模方法,详细介绍了非参数不确定模型的建模原理及过程,研究分析了非参数不确定性对声-振耦合系统的中低频响应影响。该方法在耦合系统有限元的基础上,通过引入随机矩阵来描述系统中质量阵、阻尼阵和刚度阵的不确定性,进而可以从根本上分析量化非参数不确定性对系统响应的影响。基于随机响应的置信区间分析方法,通过数值算例分析了一般声-固耦合系统在结构刚度为不确定因子时对系统声-振响应的影响。本文研究工作将为不确定声-固耦合系统的分析与优化提供有效方法,具有重要的理论意义与应用价值。(5)基于混合FE-SEA方法建立某工程机械驾驶室的混合模型,对驾驶室内的中频噪声进行了预测及分析,并通过实验对模型准确性进行了验证。针对驾驶室模型中内损耗因子及耦合损耗因子等参数存在的不确定性(风挡玻璃本身是夹层结构,且与周围结构之间存在粘弹性介质连接;板结构与驾驶室框架之间的焊连接),本文利用第三章中提出的相关计算理论,用虚拟实验的方法计算了玻璃子系统的内损耗因子及耦合损耗因子。用实验测量的方法获取了模型机械激励及空气声激励。建立了驾驶室内半无限流场模型,分析并量化了各板件结构对驾驶室内声压的贡献量。
[Abstract]:As everyone knows, any complex mechanical system can be regarded as a combination of many different subsystems. Because each part of the system in the manufacture of materials, differences in structure and size, will lead to differences in the dynamic characteristics of the local structure of the system, so that the vibration of the structure of the whole system exhibits complex hybrid vibration the characteristics of long wave produced lower substructure by the modal density and deformation produced by the structure of high density sub modes coexist in short wave deformation frequency range is quite wide in the academic circles. So the system of local vibration frequency vibration and local high-frequency vibration coexist complex vibration is generally defined as "intermediate frequency vibration system while in this band, the traditional finite element method, both the boundary element method and statistical energy analysis and loss of the validity of the calculation accuracy to a certain extent. This complex system if the vibration problem has been one of the main research topic in academic circles. Due to the complexity of combination system in manufacturing, assembly and measurement process inevitably exist error, it is because of these tiny errors caused by the uncertainty of the system. In most cases, the uncertainty of numerical small. However, with the increase of frequency, the dynamic characteristics of the system parameter changes of the more sensitive, affecting the overall dynamic characteristics of the system uncertainty is increasing gradually; in addition, many uncertain factors are coupled together, may cause a large deviation in response to actual acoustic coupling system, and even reverse phenomenon. At present, on the modeling of uncertainty is mainly confined to the non parametric uncertainty, and according to the model uncertainty of the system response and quantification Less. In addition, the uncertainty of numerical analysis and optimization methods are mainly concentrated in the uncertain structure field, it starts in the acoustic solid coupling system in the field of research is still in the stage. Based on the project of Jiangsu province science and technology support program of Jiangsu province (BE2014133), the research prospective joint Research (BY2014127-001) and the Southeast University of underwater acoustic signal processing the open fund project of Key Laboratory of Ministry of Education (UASP1301) funding, according to the typical frequency acoustic cavity structure vibration problems and uncertainties of the cavity structure dynamic response analysis are studied, and some useful conclusions are obtained. The research results have important theoretical significance and practical value to control the frequency of sound to tune structure and class structure design and vibration acoustic cavity noise. The main research contents and innovations are as follows: (1) derive the hybrid model The process and solution process, details of the Hybrid finite element-statistic energy analysis method (hybrid FE-SEA method) principle, and assuming the premise of hybrid FE-SEA method in detail. Taking the typical frequency frame plate system as the research object, established a mixed FE-SEA model. By introducing the parameter uncertainty of dynamic structure respectively the characteristics of uncertainty, affect the calculation results of the hybrid model in determining the excitation boundary uncertainty connected, draw some meaningful conclusions. (2) aiming at the problem of cavity structure with different boundary conditions of the damping loss factor and coupling loss factor is not easy to obtain, puts forward a new calculation method by experimental measurements to determine the coupling loss factor and loss factor subsystem. Among the studied with different boundary conditions for rectangular cavity loss The acquisition method, this method through the total loss measurement subsystem and subsystem structure factor between energy ratio, can be directly calculated damping loss factor and coupling loss factor. The method does not need to make any simplifying conditions, the calculation result of loss of more comprehensive response subsystem. (3) if the mixing theory established the transmission loss of pore structure with Diffuse acoustic field-Semi-infinite sound insulation based on field (DAF-SIF) prediction model of pore structure with sound insulation sound transmission characteristics, and compared with the analytical results. The influence of uncertainty on characteristics of sound insulation performance of pore plate, analysis of the structure under different boundary conditions, different transmission characteristics the opening rate and sealing conditions, provide a theoretical basis for the governance of sound insulation design and noise engineering. (4) proposed a modeling method based on random matrix theory Method, introduces the non parametric uncertainty principle and process modeling, analysis of non parametric uncertainties in the low frequency response of acoustic vibration coupling system. The method is based on the finite element coupling system, by introducing the random matrix to describe the mass matrix system, damping and stiffness matrices. The uncertainty and influence of non parameter uncertainty on the response of the system fundamentally. The confidence interval analysis method based on stochastic response, analyzed by a numerical example of general acoustic solid coupling system in structural stiffness is uncertain due to the impact of the system when the sound and vibration response. This research work will be uncertainty analysis and optimization of structure acoustic coupling system provides an effective method and has important theoretical significance and practical value. (5) mixed model hybrid FE-SEA method to establish an engineering machinery cab based on driving If the indoor noise prediction and analysis, and the accuracy of the model is verified. According to the existing cab model in loss factor and coupling loss factor and other parameter uncertainty (windshield glass itself is a sandwich structure, and the surrounding structures between joints; in viscoelastic medium between the board structure and the cab. The framework of this paper), welding connection calculation theory put forward in the third chapter, the loss factor and coupling loss factor of glass subsystem was calculated by the method of virtual experiment. Experimental method to obtain model of mechanical excitation and air acoustic excitation. Established the model of the cab semi infinite field, analyzed and quantified the contribution of each panel structure on the cab sound pressure.

【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB53

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