摘要
弧形阵列对其所在圆弧中心的重点区域进行超声导波成像检测,具有比直线阵列成像更高的横向分辨率。该文介绍了板中超声导波弧形阵列成像检测实验系统构成,详细分析了弧形阵列聚焦图像的椭圆簇轨迹特征,结合合成孔径聚焦讨论了其成像原理。该椭圆簇轨迹特征可用以分析、解释、改进图像的横向分辨率。成像实验表明:基于椭圆簇轨迹特征的合成孔径聚焦原理可用于弧形阵列成像检测,适当减小成像采样步距可使图像灰度更加平滑,成像采样距离为导波波长的1/3时成像效果最好;在圆心角小于散射点的声波散射开角时,增大阵元间距和弧形阵列圆心角可显著提高图像横向分辨率。该研究有助于将弧形阵列超声导波成像技术应用于大尺度板结构无损检测。
Imaging and inspection of ultrasonic guided waves for an arc array have higher transverse resolution than for a line array for locating defects centered around the natural focus of the arc array. An imaging and inspection system is developed using ultrasonic guided waves of an arc array using multichannel array signals. The characteristics of elliptical cluster tracks （CECT） of an arc array with ＂single transmitter and multi receivers＂ are used by synthetic aperture focusing. The CECT image can be used for analyzing, explaining and improving the transverse resolution. Imaging experiments show that synthesis aperture focusing with CECT can be used for imaging and inspection of ultrasonic guided waves for an arc array with smaller imaging-sampling step distances （ISSD） to make the image smoother. The image is the smoothest when ISSD is about 1/3 of the wave length. Larger distances between the two array elements and larger central angles of the arc array may significantly increase the transverse inspection resolution. This method provides imaging and inspection of ultrasonic guided waves in larger plate-like structures.
出处
《清华大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2012年第11期1601-1606,共6页
Journal of Tsinghua University(Science and Technology)
基金
国家自然科学基金资助项目(60871101)
关键词
弧形阵列
合成孔径聚焦
超声导波
成像检测
arc arrayl synthetic aperture focusing
ultrasonic guided wave
imaging and inspection
