相移迁移法在激光超声合成孔径聚焦技术中的应用  

Application of Phase Shift Migration Method in Laser Ultrasonic SAFT

作　　者：陈楚 应恺宁 刘念 戴鹭楠 阚威威 倪辰荫[1] Chen Chu;Ying Kaining;Liu Nian;Dai Lunan;Kan Weiwei;Ni Chenyin(School of Electronic and Optical Engineering,Nanjing University of Science&Technology,Nanjing,Jiangsu 210094,China;School of Science,Nanjing University of Science&Technology,Nanjing,Jiangsu 210094,China)

机构地区：[1]南京理工大学电子工程与光电技术学院,江苏南京210094 [2]南京理工大学理学院,江苏南京210094

出　　处：《中国激光》2021年第3期25-35,共11页Chinese Journal of Lasers

基　　金：国家自然科学基金(11974186,61975080)。

摘　　要：通过分析脉冲源激光辐照于工件表面激发的多模式、宽带超声体波信号并结合合成孔径聚焦技术(SAFT),实现了对工件内部微小缺陷的检测、定位和成像。首先基于有限元仿真模拟了激光激发超声波在含缺陷样品中的传播过程,编写了基于相移迁移法(PSM)的SAFT成像算法,然后在实验中使用激光在含缺陷样品表面激发超声波,使用激光测振仪探测超声波,并基于已有算法和探测结果对样品内缺陷进行了检测和定位,以验证算法的正确性。有限元仿真以及实验结果均表明,将激光超声技术与频域SAFT-PSM结合,能够有效地对微小缺陷进行检测和定位,且其图像重构速度快于时域SAFT,可为激光超声无损检测提供更快速的实时技术方案。Objective The positioning and even imaging of small defects inside metal workpieces can avoid unqualified workpieces.Au ultrasound imaging technology is based on the property of ultrasound which can penetrate opaque objects to obtain images of target objects,and is widely used in various fields.Traditional ultrasonic imaging data is mostly obtained by using ultrasonic transducers,such as piezoelectric transducers and electromagnetic acoustic transducers,to excite and detect ultrasonic waves on the surface of the material.However,these ultrasonic detection technologies have limitations in specific environments.On the other hand,laser ultrasonic nondestructive testing technology(NDT&E) can provide possibilities to overcome the shortcomings of traditional ultrasonic testing methods.Traditional laser ultrasonic defect detection methods include A-scan,B-scan,C-scan,etc.Most of these methods cannot accurately determine the size and location of the defect.Apart from this,the synthetic aperture focusing technology(SAFT) is widely used in the field of ultrasound imaging due to its ability of imaging of small defects and high imaging contrast.Our research combines the laser ultrasonic NDT&E with SAFT algorithm,which can realize imaging of small defect when it is used as the traditional ultrasonic transducer,and can also bring the advantages of laser ultrasound.The propagation and interaction with defects of laser ultrasound in metallic samples are numerically simulated by Comsol Multiphysics and the PSM-SAFT algorithm is compiled and verified by experiments to be suitable for laser ultrasound.Results indicate that the algorithm can effectively detect and locate small defects,and the image reconstruction speed is faster than that of the time domain SAFT algorithm.It can provide faster real-time technical solutions for laser ultrasonic NDT&E.Methods The propagation mechanism of laser ultrasound in high-strength steel samples,as well as the interaction of the high-strength steel with circular through-hole defects,was numerica

关 键 词：传感器 激光超声 合成孔径聚焦技术 相移迁移法 成像算法 无损检测 

分 类 号：TG115.28[金属学及工艺—物理冶金]