發(fā)布時(shí)間：2019-03-22 13:24

【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(guān)系著橋梁的安全使用。本文結(jié)合國(guó)家自然科學(xué)基金項(xiàng)目"基于磁致伸縮導(dǎo)波動(dòng)態(tài)聚焦原理的拱橋吊桿腐蝕斷絲在線檢測(cè)方法"(NO.61271084),開(kāi)展了拱橋吊桿導(dǎo)波無(wú)損檢測(cè)實(shí)驗(yàn)研究。本文針對(duì)傳統(tǒng)導(dǎo)波檢測(cè)方向識(shí)別方法中存在的不足,提出了基于時(shí)延估計(jì)的導(dǎo)波檢測(cè)信號(hào)方向識(shí)別方法。通過(guò)將基本互相關(guān)時(shí)延估計(jì)方法和LMS自適應(yīng)濾波時(shí)延估計(jì)方法引入到傳統(tǒng)導(dǎo)波檢測(cè)方向識(shí)別方法中,克服了傳統(tǒng)方法中方向識(shí)別能力受實(shí)際波速影響和檢測(cè)頻率受換能器限制的問(wèn)題。最后通過(guò)實(shí)驗(yàn)對(duì)本文提出的方法和傳統(tǒng)方法進(jìn)行了對(duì)比研究,證明本文提出的方法在換能器和檢測(cè)頻率匹配時(shí)比傳統(tǒng)方法的方向識(shí)別能力略強(qiáng),在換能器和檢測(cè)頻率失配時(shí)方向識(shí)別效果遠(yuǎn)遠(yuǎn)好于傳統(tǒng)方法。針對(duì)吊桿中導(dǎo)波信號(hào)嚴(yán)重頻散引起的檢測(cè)分辨力下降和信號(hào)衰減問(wèn)題,開(kāi)展了時(shí)間反轉(zhuǎn)聚焦技術(shù)的基本理論研究及其在拱橋吊桿的導(dǎo)波檢測(cè)信號(hào)頻散補(bǔ)償中的應(yīng)用研究。通過(guò)Abaqus軟件對(duì)拱橋吊桿進(jìn)行建模和仿真研究,驗(yàn)證了時(shí)間反轉(zhuǎn)聚焦方法能夠在特定位置使得拱橋吊桿中導(dǎo)波信號(hào)形成聚焦,從而實(shí)現(xiàn)對(duì)導(dǎo)波檢測(cè)信號(hào)的頻散補(bǔ)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(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U446

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