【摘要】：拱橋吊桿是現(xiàn)代中下承式拱橋重要的傳力構(gòu)件,其結(jié)構(gòu)健康狀況關系著橋梁的安全使用。本文結(jié)合國家自然科學基金項目"基于磁致伸縮導波動態(tài)聚焦原理的拱橋吊桿腐蝕斷絲在線檢測方法"(NO.61271084),開展了拱橋吊桿導波無損檢測實驗研究。本文針對傳統(tǒng)導波檢測方向識別方法中存在的不足,提出了基于時延估計的導波檢測信號方向識別方法。通過將基本互相關時延估計方法和LMS自適應濾波時延估計方法引入到傳統(tǒng)導波檢測方向識別方法中,克服了傳統(tǒng)方法中方向識別能力受實際波速影響和檢測頻率受換能器限制的問題。最后通過實驗對本文提出的方法和傳統(tǒng)方法進行了對比研究,證明本文提出的方法在換能器和檢測頻率匹配時比傳統(tǒng)方法的方向識別能力略強,在換能器和檢測頻率失配時方向識別效果遠遠好于傳統(tǒng)方法。針對吊桿中導波信號嚴重頻散引起的檢測分辨力下降和信號衰減問題,開展了時間反轉(zhuǎn)聚焦技術的基本理論研究及其在拱橋吊桿的導波檢測信號頻散補償中的應用研究。通過Abaqus軟件對拱橋吊桿進行建模和仿真研究,驗證了時間反轉(zhuǎn)聚焦方法能夠在特定位置使得拱橋吊桿中導波信號形成聚焦,從而實現(xiàn)對導波檢測信號的頻散補償。
[Abstract]:Arch bridge hanger is an important force transfer component of modern middle-bottom arch bridge, and its structural health is related to the safe use of the bridge. In this paper, combined with the project of National Natural Science Foundation of China, "on-line testing method of corrosion broken wire of arch bridge hanger based on magnetostrictive guided wave dynamic focusing principle" (NO.61271084), experimental research on non-destructive testing of arch bridge hanger by guided wave is carried out. In this paper, a new direction recognition method for guided wave detection based on time delay estimation is proposed, aiming at the shortcomings of the traditional direction recognition method for guided wave detection. The basic cross-correlation time delay estimation method and the LMS adaptive filtering delay estimation method are introduced into the traditional direction identification method of guided wave detection. It overcomes the problem that the traditional method is influenced by the actual wave velocity and the detection frequency is limited by the transducer. Finally, a comparative study of the proposed method and the traditional method is carried out through experiments. It is proved that the proposed method is a little stronger than the traditional method in direction recognition when the transducer and the detection frequency are matched. When the transducer and the detection frequency are mismatched, the direction recognition effect is much better than the traditional method. In order to solve the problem of decreasing detection resolution and signal attenuation caused by severe dispersion of guided wave signal in hanger, the basic theoretical research of time reversal focusing technique and its application in dispersion compensation of guided wave detection signal of arch bridge hanger are carried out. The modeling and simulation of arch bridge hanger is carried out by Abaqus software. It is verified that the time reversal focusing method can focus the guided wave signal in the arch bridge hanger at a specific position, thus realizing the dispersion compensation of the guided wave detection signal.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：U446

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