基于激光超声的金属构件表面微裂纹定量检测技术研究  

Micro-crack quantitative detection technique for metal component surface based on laser ultrasonic

作　　者：刘永强[1] 杨世锡[1] 刘学坤[1] LIU Yongqiang;YANG Shixi;LIU Xuekun(State Key Lab of Fluid Power and Mechatronic Systems,School of Mechanical Engineering,Zhejiang University,Hangzhou 310027,China)

机构地区：[1]浙江大学机械工程学院流体动力与机电系统国家重点实验室

出　　处：《振动与冲击》2019年第19期14-19,共6页Journal of Vibration and Shock

基　　金：国家自然科学基金(51375434)

摘　　要：传统超声无损检测技术一般需对比裂纹构件与无损构件响应数据,分析两者差异以识别裂纹;两次测量结果易受人工操作误差、外界环境变化影响,导致裂纹误检。针对该问题,提出一种基于激光超声的金属构件表面微裂纹定量检测技术,该技术通过提取激光超声波与裂纹构件作用后非线性特征参数改变量实现裂纹定量检测,无需参考无损构件响应数据,能有效减少因人工操作误差、外界环境变化引发的裂纹误检;利用激光辐照构件激发超声波,根据构件时域动态响应信号重构相空间,引入一种非线性特征参数提取方法对构件上相邻辐射点之间状态空间改变量进行评估以实现裂纹检测。构建实验系统对空压机缸体表面实际砂孔缺陷及疲劳裂纹进行检测,结果表明所提技术能有效定量检测金属构件表面微裂纹。Traditional ultrasonic nondestructive detection techniques need to compare response data of a cracked component and a nondestructive one and analyze differences between them to identify crack.Two measured results are easy to be affected by manual operation error and changes of external environment,which causes the false detection of cracks.Here,a micro-crack quantitative detection technique for metal component surface based on laser ultrasonic was proposed to tackle this problem.This technique didn’t need to refer to response data of a nondestructive component,and crack quantitative detection was realized through extracting changes of nonlinear characteristic parameters after interaction between laser ultrasonic wave and a cracked component to avoid false detection of cracks.Laser was used to irradiate a component and excite ultrasonic wave.The component’s time domain dynamic response signals were used to reconstruct a phase space.A nonlinear characteristic parameters extracting method was introduced to evaluate the state space change between adjacent radiated points on the component,and realize crack detection.A test system was built to detect actual sand hole defects and fatigue cracks on the cylinder block surface of an air compressor.The results showed that the proposed technique can be used to effectively and quantitatively detect micro-crack on metal components’surface.

关 键 词：裂纹检测 激光超声 相空间 吸引子 

分 类 号：TB57[理学—物理] TH113[理学—声学]