厚壁压力容器声发射技术声源定位误差分析

Sound Source Location Error Analysis of Acoustic Emission Technique for Thick-Wall Pressure Vessel

声发射技术(AE)已经被广泛应用到压力容器、压力管道等检验中。声源定位在整个声发射检验与评定结果过程中起重要作用,目前这方面的研究热点是如何提高定位精度。声发射技术通常采用时差定位法来检测压力容器和压力管道的缺陷,通过检测声波到达不同传感器的时间来确定声源位置。对于厚壁压力容器来说,若声源位于容器的内表面或内部,显然容器壁厚会对声源的精确定位产生一定的影响。针对此问题,详细推导并得出厚壁压力容器中声发射检测的定位误差的解析解,分析和讨论了声源定位误差的变化规律。分析结果表明,定位误差的试验值和理论分析符合良好,计算数据与试验值之间的最大误差为7.12%。当容器壁厚小于600 mm的情况下,建议实际声发射检测中对声源位置200 mm以内区域采用其他常规无损检测方法进行复验以确定实际声源位置。

Acoustic emission（AE） technique has been widely applied to pressure vessel and piping inspection. Sound source location analysis plays an important role in the whole AE inspection and evaluation process, how to improve the location precision to an extent is the research focus all over the world. For AE sound source location of pressure vessel and piping, the arrival-time difference location method is mainly used, i.e. compute arrival-time difference which sound source signals arrive at different sensors to determine the sound source location. If an active sound source is on the internal surface or in the wall not on the external surface of thick-wall pressure vessels, the location error obviously exists because of the wall thickness influence. Aiming at the problem, the sound source error for thick-wall pressure vessels is deduced in detail, the sound source location error formulas are founded and the change law of location error with the wall thickness is analyzed and discussed too. The results indicate that the location errors in the experiment are both in good agreement with those in theory with a maximum relative error of 7.12%. Furthermore, when the thickness is less than 600 mm, it is proposed that about 200 mm radius area around the source location should be rechecked by normal nondestructive testing methods to determine the actual source location by AE inspection.