超声导波在拱桥吊杆中传播特性的研究
发布时间：2018-10-31 20:50
【摘要】：吊杆广泛地应用于桥梁结构中,主要用来连接悬索和桥面系,作用是承受桥面系的载荷,由于吊杆始终处于受力状态,且工作环境较为恶劣,一旦表面的PE护套破损,就很容易导致吊杆内部断丝和锈蚀,存在很大的安全隐患,因此对吊杆的缺陷及时进行检测对于保证吊杆正常工作具有重要的意义。本文以实现拱桥吊杆超声导波无损检测为目标,深入研究了吊杆中导波传播的特性,建立了37芯拱桥吊杆的有限元仿真模型,搭建了吊杆超声导波无损检测实验平台,从仿真和实验两个角度分别对导波在吊杆中传播的频散和衰减特性进行了分析,并设计了相关的纵波和扭转波换能器。具体的研究工作包括:第一章,分析了吊杆无损检测的重要性,介绍了吊杆无损检测的主要技术,概述了吊杆检测和导波技术在国内外的研究发展现状,为后续研究指明了方向。第二章,介绍了超声导波基本理论,分析了导波的传播特性,利用半解析有限元方法求解了导波在吊杆中传播的频散曲线和频散衰减曲线,使用短时傅里叶变换和二维傅里叶变换验证了吊杆中导波传播的频散曲线的正确性。第三章,介绍了利用磁致伸缩方式激励超声导波的方法,根据不同模态导波的产生方式设计了超声导波纵波换能器和扭转波换能器。第四章,建立了吊杆的有限元模型,对导波在吊杆中的传播过程进行了仿真,通过分析仿真信号,对吊杆中纵波的频散和衰减特性进行了验证。通过缺陷检测仿真分析了扭转波的缺陷检测能力。第五章,搭建了拱桥吊杆超声导波无损检测实验平台,并利用该平台分析了偏置磁场对导波检测的影响,研究了不同频率下L(0,1)模态导波的缺陷检测能力,对比了使用磁致伸缩带材前后的实验效果,证明了将磁致伸缩带材粘贴于吊杆表面,将带材的磁致伸缩效应耦合到吊杆中,对于提高磁致伸缩换能效率有着明显效果。第六章,对本文的研究内容和结论进行了概括总结,对导波在拱桥吊杆无损检测中的发展前景和今后的研究工作进行了展望。
[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.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U448.22
[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.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U448.22
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