Classified Index: CODE: 10075 U.D.C.: NO: 20121677
A Disrtation for the Degree of M. Engineering
Technology Rearch On Wrapped Cylinder Of Acoustic Emission Testing
Candidate：Liu Yaping
Supervisor：Prof.Zhang Wanling
Prof.Shen Gongtian
Academic Degree Applied for：Master of Engineering
Specialty：Instrument and Meter Engineering
给老人的生日祝福语University：Hebei University Date of Oral Examination：June, 2014
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目前，车用纤维缠绕气瓶已应用广泛。但近年来，国内已先后发生过几次大的车用压缩天然气气瓶事故，其中以复合材料气瓶事故为主。另外，在CNG气瓶定期检验中，也发现了一定比率有危害性的表面损伤。车用压缩天然气缠绕气瓶在使用中会因碰撞造成表面损伤，从而影响其安全性。因此，针对缠绕气瓶，迫切需要一种不拆卸的、在役无损检测方法。为此，本文对缠绕气瓶疲劳过程的声发射信
号特性进行研究，初步提出了缺陷的判断方法，为实现缠绕气瓶的声发射在线检测及缺陷判断奠定了基础。完成的主要工作及成果有：
（1）对比国内外复合材料气瓶标准，国外标准在声发射检测方面较为领先，如缠绕气瓶的ASTM E-2191-2008等标准，但是国外的检测标准也不尽完善，国内目前还没有较为详尽的声发射检测标准。文中对缠绕气瓶的声发射检测标准提出详细的评价准则。
（2）在实验室中对新生产的缠绕气瓶和内胆进行疲劳的声发射试验研究，采集缠绕气瓶和内胆在疲劳过程中的大量周期信号。将内胆与缠绕气瓶的疲劳过程中的声发射信号进行统计参数综合比较，找出能够区分内胆与缠绕气瓶缺陷的参数，得出缠绕气瓶缺陷信号参数，伴随参数能量、幅度、撞击数和有效值电压峰值信号的特征发现缠绕气瓶从完好到裂纹出现直到泄露经历了三个阶段，反应了缠绕气瓶整个生命过程的声发射源特性。
（3）对有缺陷缠绕气瓶和北京在用车用缠绕气瓶进行现场声发射检测，分析采集的声发射信号特征，得出有断丝缺陷气瓶的声发射检测中升压时信号的幅度变化比较大，之后信号开始变得平缓。无缺陷在用车用缠绕气瓶的声发射信号的特征参数均在一定范围内上下波动，无明显变化趋势，没有发现异常，气瓶的性能比较稳定。
（4）观察缠绕气瓶材料、疲劳和现场的声发射信号的统计参数变化趋势，经过参数分析筛选，提取受益匪浅近义词
出有效识别缺陷的特征参数比较有效的 Hits和 RMS。分析得出缠绕气瓶无缺陷和有缺陷时特征参数的分布范围及幅度波动，初步提出了缠绕气瓶声发射检测的判断方法。
关键词缠绕气瓶疲劳声发射参数统计分析缺陷
Abstract
吃小米粥会胖吗Compresd natural gas vehicle wrapped cylinder increa rapidly in recent years. At prent, China has experienced veral major vehicle compresd natural gas cylinder accident, but the composite cylinders the most rious. In addition, in the regular inspection of CNG cylinders have found the ratio of surface damage of harm, at the same time, the surface of white spot damage in vehicle compresd natural gas wrapped cylinders has incread than in the past years .Compresd gas cylinders will be wound caud by collision with the vehicle surface damage in u which affected the cylinder’s safety. Therefore, it is urgent to find an on-rvice nondestructive testing method for the composite cylinder. Conquently, the disrtation studies AE signals characteristics of the wrapped cylinder fatigue process, also propos fault recognition method initially. All the work established the foundation for realizing AE on-line detection and fault diagnosis of the wrapped cylinder fatigue. the tasks finished are as follows:
丰硕的近义词(1)Contrasted domestic and foreign standards of composite cylinders, foreign standards is more leading in life prediction, damage control, non-destructive testing and safety design, acoustic emission detection, such as wrapped cylinders of ASTM E-2191-2008 and other standards, but testing standards abroad are not perfect .there is no more detailed acoustic emission testing standards in the country. In paper, the detailed evaluation criteria of acoustic emission testing standards of wrapped cylinder is made
(2) In the laboratory , the new wrapped cylinders and liner have a AE testing rearch during fatigue process, collecting a large number of cycle signal wrapped cylinders. The regularity of AE signal of wrapped cylinders fatigue test is analysis using the statistical parameters, lecting typical periodic signal is analysis the parameters and spectrum characteristics to find out the characteristics of AE during the wrapped cylinders fatigue process. With the parameters of Energy, Amplitude, Hits and RMS signals , wrapped cylinders has gone through three stages, reflecting the wrapped cylinders throughout the life cour of AE signal characteristics from intact to crack until the leak
(3) The defective cylinders and wrapped cylinders of bus in Beijing have a on live AE testing, then analysis of AE signal characteristics collected, The change of Amplitude is more larger in broken wire detection of wrapped cylinders when the wrapped cylinders have a AE test during the boost, the
n the signal starts to become flat. The characteristic parameters of the
