摘要
应用超声端点反射法测量薄壁工件中缺陷高度时,需要深入研究检测信号的产生机理、检测信号与缺陷的对应关系、缺陷信号的识别等。采用有限元计算方法,对测量薄壁(6 mm)工件中未焊透高度的超声端点反射法进行了数值分析。通过构造合适的有限元模型,计算得到了超声波与未焊透缺陷相互作用的散射声场,对源于缺陷上端与底部的反射回波的产生、传播过程以及含有不同高度未焊透的薄板工件的检测回波信号进行对比分析。结果表明:超声端点反射法用于薄壁工件中未焊透高度测量时,可同时得到缺陷的上端与底部反射回波,且两回波在检测得到的A扫描信号中具有一定声程差,其值与未焊透的高度呈线性关系;此外,为得到更易于识别的缺陷上端反射回波,超声检测探头可进行小幅度的位置变动。在此基础上,对平板未焊透模拟试样进行了实际超声检测试验,试验结果与有限元分析结果具有良好的吻合性。
To efficiently measure the height of flaws in thin-wall object by tip echo techniques,further investigations on generation mechanism of signals and identification of flaw echoes are necessary. Therefore,numerical analysis of tip echo technique for measuring height of incomplete penetration in thin-wall（6 mm）object was carried out by finite element method. A suitable FEM model was established,and then scattering sound field from interaction of ultrasound and incomplete penetration was calculated. The processes of generation and propagation of echoes from top and bottom of flaw were analyzed in detail and echo signals from incomplete penetration of different height were calculated and compared. The result indicates that the measurement of the penetration height in thin-wall object by tip echo technique,reflected echoes from top and bottom of the flaw can be obtained simultaneously. The sound path length between these two echoes has linear relations with the incomplete penetration height. Furthermore,the position of angle probe can be adjusted slightly to enhance the identifiability of echo from top of the flaw. Based on the above,ultrasonic testing was carried out. The experimental results agree well with the FEM analysis results.
出处
《兵器材料科学与工程》
CAS
CSCD
北大核心
2015年第4期113-118,共6页
Ordnance Material Science and Engineering
关键词
超声端点反射法
有限元方法
未焊透
高度测量
tip echo technique
finite element method
incomplete penetration
height measurement
