基于零矩尺度函数有限元的转轴裂纹识别方法与应用

发布时间：2018-03-28 13:16

本文选题：小波有限元　切入点：转轴　出处：《华中科技大学》2012年硕士论文

【摘要】：随着大型回转机械日益向高速、重载、大功率、长周期运行方向发展，使得转子的运行条件更为恶劣，容易导致转子在运行过程中出现横向裂纹。而裂纹的不断扩展，最终会导致结构的失效，并可能引发重大事故。因此，对早期结构裂纹的参数识别是工程实践中的重要课题。振动诊断法在工程裂纹识别中应用广泛，而小波有限元在处理裂纹等奇异性、大梯度问题上具有独特的优势，因此本文选取小波有限元对转轴裂纹参数识别进行研究。首先分别计算了Daubechies小波和Coiflet小波尺度函数的数值和导数值，，并推导了联系系数的计算方法，然后通过将小波尺度函数当作插值函数引入到有限元中，构造了Daubechies小波转轴单元和Coiflet小波转轴单元。把裂纹等效为无质量扭转线弹簧，建立转轴的小波有限元模型，并得到随裂纹深度和位置变化的转轴固有频率曲面。将小波有限元法与解析法进行比较，其吻合程度很高，说明了小波有限元法的有效性。对转轴的固有频率进行参数敏感性分析，由此得到实验需要注意的事项。然后进行悬臂结构转轴裂纹激振实验，获得实测固有频率，并通过等高线法对转轴裂纹参数进行识别，取得了非常好的效果。
[Abstract]:With the development of large rotating machinery towards the direction of high speed, heavy load, high power and long period operation, the operating conditions of rotor are worse, and it is easy to cause transverse cracks in the running process of rotor. Therefore, parameter identification of early structural cracks is an important subject in engineering practice. Vibration diagnosis method is widely used in engineering crack identification. Wavelet finite element has a unique advantage in dealing with crack singularity and large gradient problem, so this paper selects wavelet finite element to study the parameter identification of rotating axis crack. First, the numerical and derivative values of Daubechies wavelet and Coiflet wavelet scaling function are calculated, and the calculation method of the correlation coefficient is derived. Then the wavelet scaling function is introduced into the finite element method as an interpolation function. Daubechies wavelet axis unit and Coiflet wavelet axis unit are constructed. The crack is equivalent to a massless torsion line spring, and the wavelet finite element model of the axis is established, and the natural frequency surface of the shaft varies with the depth and position of the crack. The comparison between the wavelet finite element method and the analytical method shows that there is a good agreement between the finite element method and the analytical method. The validity of wavelet finite element method is illustrated. The parameter sensitivity analysis of the natural frequency of the shaft is carried out, and the matters needing attention in the experiment are obtained. Then, the vibration experiment of the shaft crack of the cantilever structure is carried out, and the measured natural frequency is obtained. The crack parameters of rotating shaft are identified by contour method, and the results are very good.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：O346.1;TH165.3

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