装载机驾驶室声振耦合特性及优化设计研究

发布时间：2018-03-25 15:33

本文选题：驾驶室　切入点：声振耦合　出处：《天津大学》2014年硕士论文

【摘要】：我国现代工程机械向着大型化、复杂化、和高功率化方向迅猛发展,由此产生的振动噪声问题也日渐突出。装载机作为一种广泛应用的大功率工程机械,其驾驶室室内声场环境的优劣越来越受到人们的重视,有效降低室内噪声对于改善人机环境具有重要意义。本文依托装载机低噪声改进关键技术研究课题,以某轮式装载机驾驶室为研究对象,通过仿真分析及实验测试等手段,对驾驶室振动噪声产生机理、声振耦合特性、振动特性及室内声场、结构优化等内容进行了深入研究,为低噪声驾驶室优化设计提供了技术路线,有效降低了室内噪声水平,改善了声场环境。主要研究内容如下:本文首先基于某型轮式装载机驾驶室建立驾驶室结构有限元模型、室内声腔有限元模型,通过节点关联构建声振耦合有限元模型,分别仿真计算结构模态、声腔模态及声振耦合模态,并对驾驶室声振耦合特性进行分析;基于结构模态与声振耦合模态相关性参与因子,研究声腔与结构的相互作用;采用单激励多响应法进行模态试验,验证所建声振耦合模型的准确性,为进一步分析研究提供模型基础。准确建立声振耦合模型后,本文实测典型工况下驾驶室悬置后激励信号,作为声振耦合模型的激励输入,采用模态叠加法进行频率响应分析,研究驾驶室结构对于激励的振动特性;将振动响应结果作为声学计算的边界条件,采用声学有限元法对驾驶员人耳处声压进行虚拟预测,并基于预测结果对驾驶室声场特性进行分析。为了表征驾驶室结构与声腔的共振特性及对于能量输入的缩放效果,本文进行驾驶室声学灵敏度分析,同时为板件贡献度分析及结构优化提供参考目标频率;确定关键分析目标频率,采用声传递向量法进行板件贡献度分析,找到引起关键频率噪声峰值的主要结构板件,为结构优化提供有效优化区域。在以上研究的基础上,本文分析驾驶室工作典型工况,结合声学灵敏度分析及声压虚拟预测结果确定柔度及频率等优化目标,采用折衷规划法和平均频率法,将驾驶室静态整体刚度和多阶目标频率归一为Euclidean距离的多目标函数,以自由起肋形式对驾驶室进行多目标形貌优化,有效避免了单频优化频率震荡现象,得到整体优化目标的Pareto最优解;同时基于实际制造及冲压工艺,结合板件贡献度分析结果,以直线型肋板定义约束类型,对特定板件进行形貌优化;分别对优化模型进行修正施加相同边界条件并进行二次声压虚拟预测,结果表明结构优化有效降低了驾驶室室内噪声,改善了声场环境。
[Abstract]:With the rapid development of modern construction machinery in China in the direction of large scale, complexity and high power, the vibration and noise problems are becoming more and more prominent. As a kind of high power construction machinery, loader is widely used. More and more attention has been paid to the indoor sound field environment in the cab, and it is important to reduce the indoor noise effectively for the improvement of man-machine environment. Taking the cab of a wheeled loader as the research object, the mechanism of vibration and noise generation, the coupling characteristics of sound and vibration, the indoor sound field and the structure optimization of the cab are deeply studied by means of simulation analysis and experimental test. This paper provides a technical route for the optimization design of low-noise cab, effectively reduces the level of indoor noise and improves the sound field environment. The main research contents are as follows: firstly, the finite element model of cab structure is established based on the cab of a wheeled loader. The finite element model of indoor acoustic cavity is constructed by the connection of nodes, and the structural mode, cavity mode and acousto-vibration coupling mode are simulated and calculated respectively, and the acoustic and vibration coupling characteristics of the cab are analyzed. The interaction between the cavity and the structure is studied based on the participation factor of the correlation between the structural modes and the acoustic-vibration coupling modes, and the modal test is carried out by using the single-excitation multi-response method to verify the accuracy of the proposed acousto-vibration coupling model. After the accurate establishment of the acousto-vibration coupling model, the excitation signal of the cab mounted under typical conditions is measured in this paper. As the excitation input of the acousto-vibration coupling model, the modal superposition method is used to analyze the frequency response. The vibration characteristics of cab structure to excitation are studied, the vibration response result is taken as the boundary condition of acoustic calculation, and the acoustic finite element method is used to simulate the sound pressure at the driver's ear. The acoustic field characteristics of the cab are analyzed based on the predicted results. In order to characterize the resonance characteristics of the cab structure and the cavity and the scaling effect of the energy input, the acoustic sensitivity analysis of the cab is carried out in this paper. At the same time, it provides the reference target frequency for the contribution degree analysis and structure optimization of the plate, determines the target frequency of the key analysis, uses the acoustic transfer vector method to analyze the contribution degree of the plate, and finds out the main structural plate that causes the peak noise of the key frequency. On the basis of the above research, this paper analyzes the typical operating conditions of the cab, and determines the optimization objectives such as flexibility and frequency by combining the acoustic sensitivity analysis and the virtual prediction of sound pressure. By using the tradeoff programming method and the average frequency method, the static overall stiffness and the multi-order target frequency of the cab are normalized into a multi-objective function of the Euclidean distance, and the multi-objective topography of the cab is optimized by the form of free ribbed. The single frequency optimal frequency oscillation is avoided effectively and the Pareto optimal solution of the whole optimization goal is obtained. At the same time, based on the actual manufacturing and stamping process and the analysis results of the contribution of the plate, the constraint type is defined by the linear ribbed plate. The shape of the plate is optimized and the optimization model is modified with the same boundary condition and the secondary sound pressure is predicted. The results show that the structure optimization can effectively reduce the cab interior noise and improve the sound field environment.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TH243

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