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  本文選題：聲腔　切入點：中頻　出處：《東南大學》2017年博士論文　論文類型：學位論文

【摘要】：眾所周知,任何復雜的機械系統(tǒng)都可以被視為由諸多不同子系統(tǒng)組合而成。由于系統(tǒng)的各個組成部分在制造材料、結構和尺寸方面的差異性,就導致了系統(tǒng)局部結構間動態(tài)特性的差異性,從而使得整個系統(tǒng)結構的振動在相當廣的頻率區(qū)間內(nèi)表現(xiàn)出由模態(tài)密度較低子結構產(chǎn)生的長波變形和由模態(tài)密度較高子結構產(chǎn)生的短波變形同時并存的復雜混合振動特征。學術界因此將系統(tǒng)振動中局部低頻振動與局部高頻振動同時并存的復雜振動情況籠統(tǒng)的定義為系統(tǒng)的"中頻振動"。而在此頻段內(nèi),傳統(tǒng)的有限元法、邊界元法和統(tǒng)計能量分析法均在一定程度上喪失了計算的準確性及有效性。因此,復雜組合系統(tǒng)中頻振動問題一直是學術界主要研究課題之一。由于復雜組合系統(tǒng)的子系統(tǒng)在制造、裝配和測量等過程中不可避免地存在著誤差,正是由于這些微小誤差的存在而引起了系統(tǒng)的不確定性。在大多數(shù)情況下,這些不確定性數(shù)值較小。但是,隨著頻率的升高,系統(tǒng)的動態(tài)特性對參數(shù)的變化越來越敏感,不確定性對系統(tǒng)的整體動態(tài)特性影響也逐漸增大;此外,許多不確定性因素耦合在一起,可能導致實際聲振耦合系統(tǒng)響應產(chǎn)生較大偏差,甚至出現(xiàn)反相現(xiàn)象。目前,對不確定性的建模研究主要還是局限于系統(tǒng)的非參數(shù)不確定性,而針對模型不確定性對系統(tǒng)響應的影響及量化研究較少。此外,不確定數(shù)值分析與優(yōu)化方法的研究主要集中在不確定結構領域,其在聲-固耦合系統(tǒng)領域的研究尚處于起步階段。本文在江蘇省科技支持計劃項目(BE2014133)、江蘇省產(chǎn)學研前瞻性聯(lián)合研究項目(BY2014127-001)及東南大學水聲信號處理教育部重點實驗室開放性基金項目(UASP1301)的資助下,針對聲腔結構的典型中頻聲-振問題及不確定性因素對聲腔結構動力學響應分析進行了深入研究,并取得了一些有意義的結論。該研究結果對聲腔結構及類聲腔結構的中頻聲-振設計及腔內(nèi)噪聲的控制有重要的理論意義及實用價值。本文的主要研究內(nèi)容及創(chuàng)新點如下:(1)推導了混合模型的建立過程及求解過程,詳細介紹了 Hybrid finite element-statistic energy analysis method(混合 FE-SEA 方法)的理論原理,并對混合 FE-SEA 方法的使用前提假設做了說明。以典型中頻框架-板系統(tǒng)為研究對象,建立了混合FE-SEA模型。通過引入?yún)?shù)不確定性分別研究了結構動態(tài)特性不確定性、連接邊界不確定性在確定激勵下對混合模型計算結果的影響,得出了一些有意義的結論。(2)針對具有不同邊界條件的聲腔結構的內(nèi)損耗因子和耦合損耗因子不易獲取等問題,提出了一種新的通過實驗測量來確定各子系統(tǒng)的內(nèi)損耗因子及子系統(tǒng)間的耦合損耗因子計算方法。研究了具有不同邊界條件的矩形聲腔損耗因子的獲取方法,該方法通過測量系統(tǒng)子結構總損耗因子以及子系統(tǒng)間的能量比,可直接同時計算內(nèi)損耗因子和耦合損耗因子。該方法無需做任何條件簡化,計算結果能更全面反應子系統(tǒng)的損耗特性。(3)基于中頻混合理論建立了帶孔隙隔聲結構傳遞損失的Diffuse acoustic field-Semi-infinite field(DAF-SIF)預測模型,研究了帶孔隙隔聲結構的聲傳遞特性,并與解析結果進行了對比分析。研究了不確定性對帶孔隙板隔聲性能的影響特性,分析了結構在不同邊界條件、不同開孔率及是否密封條件下的聲傳遞特性,為工程上隔聲設計及噪聲治理提供理論基礎。(4)提出了一種基于隨機矩陣理論的建模方法,詳細介紹了非參數(shù)不確定模型的建模原理及過程,研究分析了非參數(shù)不確定性對聲-振耦合系統(tǒng)的中低頻響應影響。該方法在耦合系統(tǒng)有限元的基礎上,通過引入隨機矩陣來描述系統(tǒng)中質(zhì)量陣、阻尼陣和剛度陣的不確定性,進而可以從根本上分析量化非參數(shù)不確定性對系統(tǒng)響應的影響。基于隨機響應的置信區(qū)間分析方法,通過數(shù)值算例分析了一般聲-固耦合系統(tǒng)在結構剛度為不確定因子時對系統(tǒng)聲-振響應的影響。本文研究工作將為不確定聲-固耦合系統(tǒng)的分析與優(yōu)化提供有效方法,具有重要的理論意義與應用價值。(5)基于混合FE-SEA方法建立某工程機械駕駛室的混合模型,對駕駛室內(nèi)的中頻噪聲進行了預測及分析,并通過實驗對模型準確性進行了驗證。針對駕駛室模型中內(nèi)損耗因子及耦合損耗因子等參數(shù)存在的不確定性(風擋玻璃本身是夾層結構,且與周圍結構之間存在粘彈性介質(zhì)連接;板結構與駕駛室框架之間的焊連接),本文利用第三章中提出的相關計算理論,用虛擬實驗的方法計算了玻璃子系統(tǒng)的內(nèi)損耗因子及耦合損耗因子。用實驗測量的方法獲取了模型機械激勵及空氣聲激勵。建立了駕駛室內(nèi)半無限流場模型,分析并量化了各板件結構對駕駛室內(nèi)聲壓的貢獻量。
[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.

【學位授予單位】：東南大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TB53

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