超声共振频谱测量法理论及应用性研究

发布时间：2018-01-13 22:21

本文关键词：超声共振频谱测量法理论及应用性研究　出处：《天津大学》2015年硕士论文　论文类型：学位论文

【摘要】：超声波在所测量的有限长材料中传播时,如果超声波的频率与材料的固有频率相等,就会发生共振现象。本文研究超声波共振频谱法测量的理论及其应用。首先利用一维杆的物理特性以及机械振动推导得到了有限长材料的共振频率,给出了其与长度、声速以及振动模式的关系式。介质的共振频率均随着长度的增加呈现递减趋势,并且振动模式对应的阶数越高,共振频率越大。利用该公式对铝杆和钢杆的声速进行了测量。通过建立水-钢-水的三层介质模型,分析了共振频率对透射系数和反射系数的影响,探讨了共振频率处超声波的透射和反射特性。在共振频率处,透射系数达到极大值,反射系数达到极小值,并且极大值、极小值对应的频率范围很小,透射曲线和反射曲线在共振频率处的变化比较剧烈。同时,利用探头的频谱以及透射和反射系数随频率的变化关系得到了超声波透过钢杆的透射波频谱以及被钢杆反射的反射波的频谱,分析了透射波和反射波频谱与入射波的差异。在共振频率处,透射波频谱接近于入射波;非共振频率处,反射波频谱形状接近入射波。利用发生共振时的频谱差异,建立了反映套管井I界面胶结情况的模型,并用超声波共振频谱测量法进行分析,发现借助这种差别可以判断固体材料或水泥构件中各种缺陷或者裂缝。最后,从理论上分析讨论了用超声波共振频谱法进行测量时,出现盲区的原因。
[Abstract]:The ultrasonic propagation in a finite length measurement in the material, if the natural frequency of the ultrasonic frequency and material, will be the phenomenon of resonance. This paper studies the theory and application of ultrasonic resonance spectroscopy measurement. First of all the physical and mechanical properties of one-dimensional rod vibration derived resonance frequency of finite length material, and gives the the length, velocity and vibration mode. The resonance frequency of medium with decreased length increases, and the number of vibration modes corresponding to the higher, the resonance frequency increases. The formula of velocity on the aluminum rod and steel rod were measured. Through the three layer model establishment of water - steel - water and analyzed the influence of resonance frequency on the transmission coefficient and reflection coefficient, discussed the reflection and transmission characteristics of the resonant frequency of the ultrasonic wave. At the resonant frequency, the transmission coefficient reaches the maximum value, The reflection coefficient reaches its minimum and maximum value, minimum value corresponding to the frequency range is very small, and changes the transmission curve of the reflection curve at the resonance frequency of the more intense. At the same time, the relationship between the probe spectrum and reflection and transmission coefficient changes with the frequency obtained through ultrasonic transmission wave spectrum and reflection spectrum is steel bar reflection the waves, analyzes the difference between the transmitted wave and reflected wave spectrum and incident wave. At the resonance frequency, transmission spectrum close to the incident wave; non resonant frequency, reflection wave spectrum shape close to the incident wave spectrum difference. When resonance occurs, in order to reflect well I interface cementation model. And analyzed by ultrasonic resonance spectrum measurement method, the difference can be found by the judgment of solid materials or various cement components in defects or cracks. Finally, theoretical analysis is discussed. The cause of the blind area is found when the ultrasonic resonance spectrum is used to measure.

【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB302.5;TB559

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