有限元功率流在结构振动特性分析中的应用

发布时间：2018-04-22 00:36

本文选题：有限元功率流 + 结构振动　；参考：《华北电力大学》2017年硕士论文

【摘要】：随着工业和经济的发展及生活水平的提高,人们对结构振动和噪声问题的研究也越来越深入。在以往的振动研究中,以应力、应变、速度等参量做为变量来评估振动的大小。目前阶段,振动功率流法的研究已经成为热门趋势,相比以往的参量,功率流法包括振动的力和速度两个参量,在描述振动时,功率流表现为能量的传递,具有明显的优势。并且,有限元法(FEM)是工程上常用来解决复杂工程问题的数值分析方法,现已得到包括研究领域和工程领域的广泛应用。有限元功率流法(PFFEM)是把有限元理论和功率流理论相结合,使得功率流理论在工程上的应用得到进一步扩展。本文以功率流理论为基础,使用ABAQUS二次开发做为编程,完成了不同结构的功率流可视化,并对实际对象的振动功率流的分析来加以验证。本文主要是从以下几个方面详细展开研究:第一,给出了一维梁结构的能量密度控制方程及功率流方程。使用简单的悬臂梁作为研究对象,把ABAQUS二次开发得到的有限元功率流和理论的功率流进行对比分析,结果显示两种方法吻合良好。最后使用钢管杆作为复杂的梁结构做了详细的功率流分析。在非共振频率下阻尼越大其结构体的功率消耗也就越大,但是在共振频率下其阻尼越大其结构体的功率消耗反而越小。第二,给出了二维板有限元功率流计算公式。对简单的平板结构做了振动功率流分析,得出功率流的矢量图、等长矢量图、云图和流线图四种不同的功率流表现形式。分析表明两个相碰撞的功率流在碰撞点处会出现能量汇聚点。并对复杂的浮筏隔振系统做振动功率流分析,分析显示频率越大传递到筏架和地板的功率越小,激励力的激振频率越大其隔振效果越好。第三,引入振动功率流理论。使用ABAQUS建立了轴承基座的有限元模型,并进行了模态分析。使用ABAQUS二次开发结合功率流理论实现了轴承基座在故障状态下的能量传递矢量图及功率流云图。结果显示,裂纹会加大轴承基座的振动。第四,利用结构声强理论,对结构瞬态响应的有限元功率流做了研究。把有限元功率流理论从稳态分析引入到瞬态分析领域。扩宽了有限元功率流的应用范围。使用钢球和钢块的碰撞作为模型,研究并分析了碰撞瞬态响应过程中的能量传递过程,得出了整个碰撞过程中的时间历程功率流云图动画及功率流矢量动画。并且在分析过程中验证了无旋波和等容波的存在,比起应力波,能量波表现出明显的优势。
[Abstract]:With the development of industry and economy and the improvement of living standard, more and more researches on structural vibration and noise have been carried out. In previous vibration studies, stress, strain, velocity and other parameters are used as variables to evaluate the magnitude of vibration. At present, the research of vibration power flow method has become a hot trend. Compared with the previous parameters, the power flow method includes two parameters, the force and velocity of vibration. When describing vibration, the power flow is characterized by energy transfer, which has obvious advantages. In addition, FEMM (finite element method) is a numerical analysis method, which is often used to solve complex engineering problems in engineering, and has been widely used in both research and engineering fields. The finite element power flow method (PFFEMM) combines the finite element theory with the power flow theory, which further expands the application of the power flow theory in engineering. Based on the theory of power flow, the visualization of power flow with different structures is accomplished by using ABAQUS secondary development, and the analysis of the vibration power flow of the actual object is verified. In this paper, the following aspects are studied in detail: first, the energy density governing equation and power flow equation of one-dimensional beam structure are given. Using a simple cantilever beam as the research object, the finite element power flow obtained by ABAQUS secondary development is compared with the theoretical power flow. The results show that the two methods are in good agreement with each other. Finally, the power flow analysis of the steel pipe rod as a complex beam structure is done in detail. The higher the damping at the non-resonant frequency, the greater the power consumption of the structure, but the smaller the power consumption of the structure is at the resonance frequency. Secondly, the two-dimensional finite element power flow calculation formula is given. The vibration power flow of a simple flat plate is analyzed, and four different power flow representations are obtained, such as vector diagram, isometric vector diagram, cloud diagram and streamline diagram. The analysis shows that the energy convergent point will appear at the collision point of the two colliding power flow. The vibration power flow analysis of the complex floating raft vibration isolation system shows that the larger the frequency is, the smaller the power of the raft and floor is, the greater the exciting frequency of the excitation force is, the better the isolation effect is. Thirdly, the theory of vibration power flow is introduced. The finite element model of bearing base is established by ABAQUS and modal analysis is carried out. The energy transfer vector diagram and power flow cloud diagram of bearing base in fault state are realized by ABAQUS secondary development combined with power flow theory. The results show that the crack will increase the bearing base vibration. Fourthly, the finite element power flow of the transient response of the structure is studied by using the theory of structural sound intensity. The finite element power flow theory is introduced from steady state analysis to transient analysis. The application of finite element power flow is broadened. Using the collision between steel ball and steel block as the model, the energy transfer process in the transient response process of the collision is studied and analyzed. The time history power flow cloud animation and the power flow vector animation in the whole collision process are obtained. The existence of non-rotating wave and isovolumic wave is verified in the process of analysis, and the energy wave has obvious advantages over the stress wave.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH113.1

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