磁致伸缩扭转波激励模型与影响因素研究

发布时间：2018-04-02 02:36

本文选题：磁致伸缩　切入点：扭转导波　出处：《南昌航空大学》2017年硕士论文

【摘要】：管道作为油气集输的主要运输方式,在生产运输方面占有重要的地位。管道在长期使用以及特殊环境下所产生的缺陷成为油、气和石化产业的主要问题。随着国家经济迅速发展,管道应用数量也随之增加,相应的管道在役安全状况以及使用寿命预测工作也急需加强,以保证正常生产运转。因此,如何快速、准确的实现对管道在役状况的检测,成为当前无损检测的首要任务。本论文在国家自然科学基金(51261024,51675258)、国家重点研发计划项目(2016YFF0203000)、江西省教育厅科学技术研究项目(GJJ150699)和广东省数字信号与图像处理技术重点实验室开放课题(2014GDDSIPL-01)共同资助下开展研究的,采用磁致伸缩扭转模态导波传感器对铁磁性管道的进行非接触无损检测。扭转模态导波的传播特性不受管道中液体的存在的影响,并且T)1,0(模态在所有频率下是非频散的。该类型传感器能够实现单点检测,且产生的导波传播距离远、速度快。然而检测信号信噪比较低是当今磁致伸缩超声导波检测的的主要缺点,因此研究力磁耦合作用下磁致伸缩扭转导波的激励和其影响因素对于提升导波检测效率有重大意义。本文从相关理论出发,仿真计算和实验研究两方面相结合对磁致伸缩扭转模态导波传感器展开研究。首先,详细阐述磁致伸缩导波检测技术的相关基础理论。介绍了铁磁性材料的磁致伸缩效应基本特征以及对导波检测系统的换能机理做了详细描述,然后根据导波的多模态性和频散特性给出了扭转导波的频散方程。同时结合文献给出了针对铁磁性材料多场耦合的线性模型。其次,介绍了磁致伸缩扭转模态导波的检测原理和传感器结构,还包括圆管中扭转波的传播以及扭转模态导波的激励过程控制方程。利用有限元软件COMSOL建立了扭转模态导波传感器激励端的三维力磁耦合数值仿真模型,对其进行加载求解,得到管道内部的磁场分布情况。在此基础上,对管道内部靠近磁场的某一质点进行磁致伸缩力的位移分析,通过质点在周向和轴向的振动规律分析数值模型激励出的导波特性,并与铁磁性材料扭转模态导波的传播特性相比较。研究表明,铁磁性管道在周向偏置磁场作用下,与动态磁场的合成的方向较为单一,并且磁致伸缩效应占据主导地位。最后根据仿真结果确定该激励模型产生的导波符合铁磁性材料扭转模态导波的传播特性,即以周向振动为主,产生的波沿管道轴向传播,传播方向与质点振动方向相垂直。说明通过该仿真分析能够得到由力磁声多场耦合产生的应变,能够真实反映扭转模态磁致伸缩导波,为后续研究激励导波影响因素以及导波增强研究提供了基础。再次,对磁致伸缩扭转模态导波检测系统搭建了实验平台,通过计算激励出的导波的波速并与理论扭转波的波速作对比,从而确定实验激励出的导波模态为扭转波。针对周向偏置磁场作用下建立的铁磁性管道激励扭转波的仿真模型,从激励信号的电流强度、频率、周期数三个方面讨论不同影响因素下磁致伸缩激励传感器作用区域内质点振动位移的变化情况。为了验证仿真结果的有效性,对钢管分别进行了不同影响因素下的检测实验,并对实验采集到的波形进行分析。结果表明,随着激励信号条件的改变,质点振动幅值和回波的峰值都产生了一定规律的变化,可以从中分析选择最优激励条件,且仿真结果和实验结果的变化规律相一致,因此该仿真模型可作为磁致伸缩导波激励检测方面研究的参考。最后,对磁致伸缩扭转模态导波激励传感器结构进行优化,采用交叉线圈式磁致伸缩扭转模态导波传感器结构对管道进行超声检测。首先介绍了偏置磁场在磁致伸缩导波传感器中的影响和作用。其次介绍了交叉线圈式激励传感器的原理以及构造,通过数值仿真验证交叉线圈式的磁致伸缩传感器能够有效的激励出扭转波并且证明了管道中合成磁场强度矢量方向?对于质点振动幅值是有影响的。结果表明,在不同材质中,总存在一个最佳的?方向使得质点振动幅值最好。然后利用交叉线圈式的传感器结构进行实验,结果表明交叉线圈式传感器激励能量能用于产生扭转波,并对仿真研究进行了实验验证,二者具有良好的一致性。因此,交叉线圈技术的磁致伸缩传感器是用于管道检查的有用且有效的工具,在本文实验条件下,当动态磁场强度保持一定时,与环形线圈磁化镍带得到偏置磁场的合成磁场强度矢量方向接近某一最佳方向时,导波幅值最好,有利于提升信噪比和对缺陷的灵敏度。
[Abstract]:As the main mode of transportation pipeline of oil and gas transportation, plays an important role in the production of transport. Pipeline defects generated in the long-term use and special environment become the main problems of oil, gas and petrochemical industry. With the rapid development of national economy, the number of pipeline application increases, the corresponding pipeline in service security situation work and life prediction also needs to be strengthened, in order to ensure the normal operation of production. Therefore, how to quickly, to realize the detection of pipeline in service condition accurately, become the primary task of nondestructive testing. The natural science foundation of the state (5126102451675258), the national key research project (2016YFF0203000), the Education Department of Jiangxi province the science and technology research project (GJJ150699) in Guangdong province and the open project of digital signal and image processing technology key laboratory (2014GDDSIPL-01) research funded under the mining Modal guided wave sensor on the ferromagnetic pipeline for nondestructive detection with magnetostrictive torsion. Propagation characteristics of torsional modes of guided waves is not affected by the influence of the presence of liquid in the pipe, and the T (1,0) mode at all frequencies is nondispersion. This type of sensor can achieve single point detection, and the guided wave propagation distance and speed. However, the detection signal in low SNR is the magnetostrictive ultrasonic guided wave detection of the main faults, so the study of magnetic force coupling for magnetostrictive torsional guided wave excitation and its influencing factors to improve the efficiency of guided wave detection is of great significance. This paper from the relevant theories. Simulation and experimental study of two combination of magnetostrictive torsional mode guided wave sensor is researched. Firstly, elaborated the magnetostrictive guided wave detection technology is introduced. The basic theory of ferromagnetic material The basic characteristics of the magnetostrictive effect of guided wave detection system to the mechanism described in detail, and then according to the guided wave multi-mode and dispersion characteristics are given torsional guided wave dispersion equation. At the same time, combined with the literature given for ferromagnetic material of multi field coupling linear model. Secondly, introduced. Torsion sensor detection principle and structure of the magnetostrictive guided wave modes, including torsional wave propagation in pipe and torsional excitation process control equation of guided wave mode was established. By numerical simulation of torsional modes of magnetic coupling model of three axis force sensor excitation wave end by using finite element software COMSOL, loading and solving the magnetic. The distribution of the internal pipe. Based on the analysis of displacement of a particle inside the pipeline near the magnetic field of the magnetostrictive force, through the analysis of particle vibration law in the circumferential and axial number The value of the incentive model of guided wave characteristics and propagation characteristics of torsional modes of guided waves and the ferromagnetic material is compared. The results show that the ferromagnetic pipeline in the circumferential bias magnetic field, magnetic field and dynamic synthesis direction is single, and the magnetostrictive effect dominates. Finally, according to the simulation results to determine the incentive the model accords with the guided wave propagation characteristics of torsional modes of guided waves in ferromagnetic materials, the circumferential vibration, wave generated along the pipe axial propagation, propagation direction and perpendicular to the direction of particle vibration. Through the simulation analysis of strain can be produced You Li magneto acoustic multi field coupling, can reflect the magnetostrictive torsional mode the telescopic guide wave, guided wave factors and guided wave enhanced research provides a foundation for the further research on incentive. Again, the magnetostrictive torsional mode guided wave detection system to build an experimental platform. Too excited to calculate the velocity of guided wave and torsional wave velocity theory for comparison, to determine the experimental excitation of guided wave modes for torsional wave. The ferromagnetic pipeline for circumferential bias magnetic field established simulation model of torsional wave excitation, the frequency from the current intensity, excitation signal, discuss the changes of different under the influence of the magnetostrictive sensor excitation region particle vibration displacement of three cycle. In order to verify the validity of the simulation results, the pipe experiments were carried out under different factors detection, and the collected waveforms were analyzed. The results show that as the excitation signal conditions change, change of peak particle the amplitude of vibration and echo have certain rules, can be analyzed to select the optimum excitation conditions, consistent variation and simulation results and experimental results, so the imitation It can be used as a model of magnetostrictive guided wave excitation and detection of reference. Finally, the magnetostrictive torsional mode guided wave excitation sensor structure optimization, torsion wave sensor structure by ultrasonic detection of the pipeline mode guided by cross coil magnetostriction. First introduced the influence of guide wave sensor bias magnetic field in magnetostrictive effect and secondly introduces the principle of cross coil excitation and sensor structure, numerical simulation results show that the magnetostrictive sensor cross coil can effectively excite torsional waves and that the synthesis of magnetic field intensity vector direction in the pipeline? Has an impact on the particle vibration amplitude. The results showed that in different materials, there is always a the best direction makes the vibration amplitude? Best. And then use the sensor structure cross coil experiments, results show that cross the line Ring type sensor excitation energy can be used to produce torsion wave, and the simulation is verified by experiments, the two have good consistency. Therefore, the magnetostrictive sensor cross coil technique is a useful and effective tool for pipeline inspection, under this experimental conditions, when the dynamic magnetic field strength constant, close to a an optimal synthesis direction of magnetic field intensity vector direction of the bias magnetic field and magnetization loop nickel belt, guided wave amplitude is best, is conducive to enhancing the SNR and the defect sensitivity.

【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

【参考文献】