机械设备薄板件的声发射波束形成缺陷定位

Location of Acoustic Emission Beamforming Defects in Thin Plates of Mechanical Equipment

针对薄板件不易察觉的内部缺陷,需要在不能破坏薄板件基础上进行无损检测,其中声发射无损检测应用较为广泛。声发射无损检测最常用的直线阵列存在垂直于阵列方向定位分辨率较低的问题,同时波束形成产生的旁瓣和主瓣较宽会影响定位精度。对此提出了针对薄板件内部缺陷的低频结合高频二次声发射波束形成定位新方法,即先通过分析主瓣、旁瓣参数与最大旁瓣级MSL来确定信号定位高低两种频带,再通过信号包络低频定位确定主瓣范围,最后通过确定的主瓣范围缩小扫描范围进行信号滤波高频定位。结果表明,该法避免了波束形成主瓣较宽及存在旁瓣的影响,对薄板件缺陷定位精度很高,同时还解决了直线阵列垂直于阵列方向定位分辨率较低的问题。

For the internal defects that are not easy to detect for thin plate parts, we need to conduct non-destructive testing on the basis of not destroying the thin plate parts. Among them, acoustic emission non-destructive testing is widely used. The linear array most commonly used in acoustic emission nondestructive testing has the problem of low location resolution perpendicular to the array direction. Meanwhile, the wide side lobes and main lobes produced by beam forming will affect the location accuracy. In this regard,this paper proposes a new method of low-frequency combined with high-frequency secondary acoustic emission beamforming location for internal defects of thin plate parts, which is to determine the high and low frequency bands of signal location by analyzing the main lobe, side lobe parameters and the maximum side lobe level MSL. Then the main lobe range is determined by low-frequency location of the signal envelope, and finally the scanning range is reduced by the determined main lobe range to perform signal filtering and highfrequency location. The results show that this method avoids the influence of the wide beam forming main lobe and the presence of side lobes, and the location accuracy of the thin plate defects is very high. It also solves the problem of low location resolution of the linear array perpendicular to the array direction.