本文關(guān)鍵詞：超聲共振頻譜測量法理論及應(yīng)用性研究　出處：《天津大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 超聲波 共振頻率 透射 反射 頻譜 測量

【摘要】：超聲波在所測量的有限長材料中傳播時,如果超聲波的頻率與材料的固有頻率相等,就會發(fā)生共振現(xiàn)象。本文研究超聲波共振頻譜法測量的理論及其應(yīng)用。首先利用一維桿的物理特性以及機械振動推導(dǎo)得到了有限長材料的共振頻率,給出了其與長度、聲速以及振動模式的關(guān)系式。介質(zhì)的共振頻率均隨著長度的增加呈現(xiàn)遞減趨勢,并且振動模式對應(yīng)的階數(shù)越高,共振頻率越大。利用該公式對鋁桿和鋼桿的聲速進行了測量。通過建立水-鋼-水的三層介質(zhì)模型,分析了共振頻率對透射系數(shù)和反射系數(shù)的影響,探討了共振頻率處超聲波的透射和反射特性。在共振頻率處,透射系數(shù)達到極大值,反射系數(shù)達到極小值,并且極大值、極小值對應(yīng)的頻率范圍很小,透射曲線和反射曲線在共振頻率處的變化比較劇烈。同時,利用探頭的頻譜以及透射和反射系數(shù)隨頻率的變化關(guān)系得到了超聲波透過鋼桿的透射波頻譜以及被鋼桿反射的反射波的頻譜,分析了透射波和反射波頻譜與入射波的差異。在共振頻率處,透射波頻譜接近于入射波;非共振頻率處,反射波頻譜形狀接近入射波。利用發(fā)生共振時的頻譜差異,建立了反映套管井I界面膠結(jié)情況的模型,并用超聲波共振頻譜測量法進行分析,發(fā)現(xiàn)借助這種差別可以判斷固體材料或水泥構(gòu)件中各種缺陷或者裂縫。最后,從理論上分析討論了用超聲波共振頻譜法進行測量時,出現(xiàn)盲區(qū)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.

【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB302.5;TB559

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本文編號：1420805