摘要
将脉冲激光的空间展开与激光超声无损检测相结合,数值分析及实验研究了激光瞬态光栅作用于铝合金板的结构响应。数值分析了反射-吸收综合模型框架下表面粗糙度对吸收率的影响,进行了直径1 mm外型、脉冲宽度1 ns、单脉冲6 mJ输入下激光瞬态光栅激励过程的仿真,并开展了相同能量条件下束斑点光源、有限长度线光源的比对分析;数值分析结果表明,观测距离小于等于4 mm的范围内,瞬态光栅激发下峰值为点源激发的2~5倍,且结构表面能量密度约为点源模式的1%、线源模式的12.7%。开发了瞬态光栅模块并搭建了激发-检测实验系统,结合49.36 mm×49.80 mm×4.97 mm尺寸的铸铝平板进行了验证比对。实验结果表明,60 kHz高通滤波下噪声幅值约为1 nm,距离光栅中心位置2 mm处表面位移峰值的相对偏差最大值为8.91%、10 mm处信号时延对应的声表面波速度偏差为6.62%。
Ultrasonic Nondestructive Testing(NDT)supports field use and has a strong resolution,which is a key developing method in the field of structural health supervision and testing.In recent years,contacttype technical paths such as patch detection,medium coupling detection,and air coupling detection based on piezoelectric sensors have been formed,which are widely applied to many industries.With the integration of high-quality pulsed laser technology and the research on the mechanism of laser-matter interaction,the detection technology of pulsed laser-excited ultrasound has gradually developed.This technology is expected to solve the problems of surface pollution and fixed detection area caused by traditional piezoelectric-excited adhesive sensors and coating coupling agents.The ultrasonic wave excited by pulsed laser includes longitudinal wave,transverse wave and surface wave,and its propagation velocity is related to the density and elastic constant of the material.In the past,the spot source mode and line source mode of a pulsed laser beam,as well as the line source array mode modulated by lens array and fiber bundle with fixed physical structure,limited the flexibility of spatial expansion of pulsed laser,and also restricted the development of structural response characteristics and signal-structure correlation analysis under the new excitation mode.The disadvantages of pulsed laser excitation are:the monochromatic coherence of laser restricts the modulation ability of beam spot,which leads to the limitation of ultrasonic time-frequency mode,meanwhile,the structural damage threshold limits the energy of pulsed laser,which leads to the shortage of ultrasonic signal intensity.In this paper,the spatial expansion of pulsed laser is combined with laser ultrasonic nondestructive testing technology.Then,the structural response of laser transient grating acting on aluminum alloy plate is studied from two aspects:numerical analysis and experimental research by adopting the idea of numerical analysis to reveal the law and e
作者
姚东
高波
宋英政
李群
高贵龙
YAO Dong;GAO Bo;SONG Yingzheng;LI Qun;GAO Guilong(Rocket Force University of Engineering,Xi′an 710025,China;Shanghai Academy of Spaceflight Technology,Shanghai 200233,China;Xi′an Jiaotong University,Xi′an 710049,China;Xi′an Institute of Optics and Precision Mechanics,Chinese Academy of Sciences,Xi′an 710119,China)
出处
《光子学报》
EI
CAS
CSCD
北大核心
2022年第9期217-227,共11页
Acta Photonica Sinica
基金
国家自然科学基金(No.62005311)。
关键词
超声无损检测
激光激发
栅形空间调制
能量密度
信号强度
Ultrasonic nondestructive testing
Laser excitation
Grating spatial modulation
Energy density
Signal intensity
