【摘要】：吊桿廣泛地應(yīng)用于橋梁結(jié)構(gòu)中,主要用來(lái)連接懸索和橋面系,作用是承受橋面系的載荷,由于吊桿始終處于受力狀態(tài),且工作環(huán)境較為惡劣,一旦表面的PE護(hù)套破損,就很容易導(dǎo)致吊桿內(nèi)部斷絲和銹蝕,存在很大的安全隱患,因此對(duì)吊桿的缺陷及時(shí)進(jìn)行檢測(cè)對(duì)于保證吊桿正常工作具有重要的意義。本文以實(shí)現(xiàn)拱橋吊桿超聲導(dǎo)波無(wú)損檢測(cè)為目標(biāo),深入研究了吊桿中導(dǎo)波傳播的特性,建立了37芯拱橋吊桿的有限元仿真模型,搭建了吊桿超聲導(dǎo)波無(wú)損檢測(cè)實(shí)驗(yàn)平臺(tái),從仿真和實(shí)驗(yàn)兩個(gè)角度分別對(duì)導(dǎo)波在吊桿中傳播的頻散和衰減特性進(jìn)行了分析,并設(shè)計(jì)了相關(guān)的縱波和扭轉(zhuǎn)波換能器。具體的研究工作包括:第一章,分析了吊桿無(wú)損檢測(cè)的重要性,介紹了吊桿無(wú)損檢測(cè)的主要技術(shù),概述了吊桿檢測(cè)和導(dǎo)波技術(shù)在國(guó)內(nèi)外的研究發(fā)展現(xiàn)狀,為后續(xù)研究指明了方向。第二章,介紹了超聲導(dǎo)波基本理論,分析了導(dǎo)波的傳播特性,利用半解析有限元方法求解了導(dǎo)波在吊桿中傳播的頻散曲線和頻散衰減曲線,使用短時(shí)傅里葉變換和二維傅里葉變換驗(yàn)證了吊桿中導(dǎo)波傳播的頻散曲線的正確性。第三章,介紹了利用磁致伸縮方式激勵(lì)超聲導(dǎo)波的方法,根據(jù)不同模態(tài)導(dǎo)波的產(chǎn)生方式設(shè)計(jì)了超聲導(dǎo)波縱波換能器和扭轉(zhuǎn)波換能器。第四章,建立了吊桿的有限元模型,對(duì)導(dǎo)波在吊桿中的傳播過(guò)程進(jìn)行了仿真,通過(guò)分析仿真信號(hào),對(duì)吊桿中縱波的頻散和衰減特性進(jìn)行了驗(yàn)證。通過(guò)缺陷檢測(cè)仿真分析了扭轉(zhuǎn)波的缺陷檢測(cè)能力。第五章,搭建了拱橋吊桿超聲導(dǎo)波無(wú)損檢測(cè)實(shí)驗(yàn)平臺(tái),并利用該平臺(tái)分析了偏置磁場(chǎng)對(duì)導(dǎo)波檢測(cè)的影響,研究了不同頻率下L(0,1)模態(tài)導(dǎo)波的缺陷檢測(cè)能力,對(duì)比了使用磁致伸縮帶材前后的實(shí)驗(yàn)效果,證明了將磁致伸縮帶材粘貼于吊桿表面,將帶材的磁致伸縮效應(yīng)耦合到吊桿中,對(duì)于提高磁致伸縮換能效率有著明顯效果。第六章,對(duì)本文的研究?jī)?nèi)容和結(jié)論進(jìn)行了概括總結(jié),對(duì)導(dǎo)波在拱橋吊桿無(wú)損檢測(cè)中的發(fā)展前景和今后的研究工作進(jìn)行了展望。
[Abstract]:The suspension rod is widely used in the bridge structure, mainly used to connect the suspension cable and the bridge deck system, the function is to bear the load of the bridge deck system, because the suspender is always in the stress state and the working environment is relatively bad, once the surface PE sheath is damaged, It is very easy to lead to wire breakage and corrosion inside the suspender, and there is a great potential safety hazard. Therefore, it is very important to detect the defects of the suspender in time to ensure the normal operation of the suspender. In this paper, the ultrasonic guided wave nondestructive testing (NDT) of the suspender of arch bridge is taken as the goal, the characteristics of guided wave propagation in the suspender are deeply studied, the finite element simulation model of the suspender of 37 core arch bridge is established, and the experimental platform of ultrasonic guided wave nondestructive testing (NDT) of the suspender is built. The dispersion and attenuation characteristics of guided wave propagating through the boom are analyzed from the point of view of simulation and experiment, and the related longitudinal and torsional wave transducers are designed. The specific research work includes: in the first chapter, the importance of non-destructive testing of suspenders is analyzed, the main techniques of nondestructive testing of suspenders are introduced, and the research and development status of non-destructive testing and guided wave technology at home and abroad are summarized. It points out the direction for further study. In the second chapter, the basic theory of ultrasonic guided wave is introduced, and the propagation characteristic of guided wave is analyzed. The dispersion curve and attenuation curve of guided wave propagating through the boom are solved by semi-analytical finite element method. Short-time Fourier transform and two-dimensional Fourier transform are used to verify the correctness of the dispersion curve of guided wave propagation in the boom. In chapter 3, the method of exciting ultrasonic guided wave by magnetostrictive mode is introduced, and the ultrasonic guided wave longitudinal wave transducer and torsional wave transducer are designed according to different modes of guided wave generation. In chapter 4, the finite element model of the suspender is established, and the propagation process of the guided wave in the boom is simulated. By analyzing the simulation signal, the dispersion and attenuation characteristics of the longitudinal wave in the boom are verified. The defect detection ability of torsion wave is analyzed by defect detection simulation. In the fifth chapter, the experimental platform of ultrasonic guided wave nondestructive testing for arch bridge suspension rod is built, and the influence of bias magnetic field on guided wave detection is analyzed, and the defect detection ability of L _ (0 ~ (1) mode guided wave at different frequencies is studied. The experimental results before and after the use of magnetostrictive strip are compared. It is proved that the magnetostrictive effect of magnetostrictive strip attached to the surface of the suspension rod and the magnetostrictive effect of the strip coupled to the suspender have obvious effect on improving the efficiency of magnetostrictive energy transfer. In the sixth chapter, the research contents and conclusions of this paper are summarized, and the development prospect and future research work of guided wave in nondestructive testing of arch bridge suspenders are prospected.
【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)】：U448.22

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