【作者】 张虹；

【导师】 靳世久； 李一博；

【作者基本信息】 天津大学 ， 精密仪器及机械， 2007， 硕士

【摘要】 管道运输作为与公路、铁路、航空、水运并驾齐驱的五大运输行业之一,在国民经济和现代工业方面发挥着越来越大的作用。研究先进的管道无损检测技术,对于保障管道运输的安全稳定运行,减少和避免环境污染具有重要意义。本文对基于声发射方法的管道缺陷和泄漏检测技术进行了研究,为管道声发射检测进入工程应用提供了经验和依据。本文研究了管道声发射检测的现有技术。基于声发射现象产生的机理和声发射检测的基本原理,并根据突发型信号和连续型信号的不同特点,研究了管道裂纹信号和泄漏信号的形成机制、波形和频谱特征。本文对管道腐蚀裂纹声发射信号的检测进行了研究,采用了Nielsen-Hsu断铅法模拟管道裂纹的产生。根据实际检测中出现的现象及采集的数据,分析了裂纹信号在传播过程中的衰减变化、时差测量方法对定位的影响,以及产生漏定位和伪定位的原因。提出了改变定时参数、测量实际波速、绘制衰减曲线的补偿方法,并验证了补偿效果。本文分析了管道泄漏检测的特点,定性判断了管道泄漏的发生。研究了管道泄漏声发射信号的频谱和能量随泄漏孔大小、管道压力、信号传播距离等的变化规律。分析了管道泄漏信号定位时的误差,采用相关分析的方法实现对泄漏的定位。从去噪的角度,提出了采用小波包分析信号处理方法,并进一步验证提高了定位精度。更多还原

【Abstract】 Pipeline transportation is playing a more and more important part in national economy and modern enterprise, which is one of the five chief transporting industries with others like highway, railway, air-ferry and water carriage. And advanced non-destructive inspection technology is the key to insure safe and reliable operation of pipeline, as well as avoid environmental pollution. This dissertation mainly researched on acoustic emission corrosions and leakage detection technology for pressure pipeline.The present technology of acoustic emission detection is been studied. Based on the mechanism of AE generation and basic principle of acoustic emission, formation mechanism, waveform and spectrum features of AE crack and leak signals were analyzed according to the differences between sudden-signal and continuous signal. Simulated by Nielsen-Hsu lead broken, the AE crack signal of pipeline was researched. According to the phenomena and data acquired in real detection, AE crack signal attenuation during transmission process and the impact factors cased by time-difference measurement were analyzed, and compensation methods, such as changing the time parameters, measuring the actual velocity, and drawing the attenuation curve and so on, were put forward and certificated.The pipeline leakage was judged qualitatively and quantificationally from the pipeline leakage characteristics. The rule of pipeline leak AE parameters varying with size of the leaking point, pressure in pipeline, and propagating distance was studied in detail. The leak location error was analyzed, and correlation analysis method was used to acquire the leak position. Further more, wavelet analysis method was raised to wipe off noise, and was proved to be more effective.更多还原