摘要
超声衍射时差法（Time of flight diffraction,TOFD）中由于探头具有一定声束宽度使得缺陷D扫描图像中存在甩弧现象,导致检测图像横向分辨率差,缺陷起始位置确定困难,长度定量误差大。为了提高缺陷长度定量精度,引入合成孔径聚焦技术（Synthetic aperture focusing technology,SAFT）,并建立D扫描图像SAFT数学模型。借助CIVA仿真软件,对长度范围为5.0~45.0 mm的9个矩形槽进行TOFD检测D扫描模拟,并利用SAFT对D扫描图像进行处理与重建,结果显示缺陷的有效衍射信号得到增强,甩弧现象减弱甚至消失;对于长度为5.0 mm的矩形槽,经SAFT处理后,缺陷定量误差为-0.4 mm。将该方法应用到长度分别为5.0 mm和40.0 mm的表面开口槽试验D扫描图像处理中,缺陷长度定量误差分别为0.4 mm和0.8 mm。研究结果表明,通过D-SAFT技术能够有效提高缺陷D扫描图像横向分辨率,实现缺陷长度精确定量。
In time of flight diffraction（TOFD） technology,the D-scan image has poor lateral resolution,large quantitative error of crack length and arcs at the crack tip due to the wide beam of transducers.In order to improve the sizing accuracy of crack length,the synthetic aperture focusing technology（SAFT） is introduced and a mathematical model of SAFT processing on the D-scan image is built.Based on CIVA software,nine rectangular cracks is established and the ultrasonic TOFD D-scan is simulated.The range of crack length is from 5.0 mm to 45.0 mm.The effective diffraction signals of cracks are enhanced and the arcs at the crack tip are weakened in the simulated D-scan image which is processed and reconstructed by SAFT.For the rectangle crack with a length of 5.0 mm,the measurement error is only-0.4 mm.This method is verified in the experiments of two surface breaking notches,of which the length is 5.0 mm and 40.0 mm,the quantification errors are 0.4 mm and 0.8 mm respectively.It shows that D-SAFT technique can be utilized to obtain high resolution D-scan image and accurately measure the crack length.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2015年第18期20-25,共6页
Journal of Mechanical Engineering
基金
十二五国防技术基础科研(Z0220120001)
十二五国防技术基础科研(Z022014T001)资助项目
关键词
超声衍射时差法
合成孔径聚焦技术
甩弧
缺陷长度定量
time of flight diffraction
synthetic aperture focusing technology
arcs
flaw length sizing
