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为解决飞行器复合材料构件的非接触、高精度无损检测问题,提出基于关节型机器人的激光超声检测系统及光声学参量匹配方法。采用有限元方法建立层状复合材料模型,计算分析材料层状各向异性导致激光超声的非对称分布、声束倾斜和畸变特征,结合实验分析得出利用激光超声表征分层的光声学参量匹配方法。在系统设计上,利用1 064 nm波长的Nd:YAG脉冲激光器激励超声波,利用基于光折变效应的双波混合干涉测量系统探测超声信号,激励和探测激光由光纤传导并投射至被检测工件表面,采用精密六轴关节型机器人作为C型扫描装置,建立系统的实验室原型,实现碳/环氧复合材料试样的C型扫描检测,得到试样中模拟缺陷的分布、形状和尺寸特征,验证了检测系统及参量匹配方法的有效性。研究结果表明,研制的机器人辅助激光超声检测系统可以实现碳/环氧复合材料内部直径1 mm以上分层的检测与成像,在飞行器复合材料构件的无损检测方面具有应用前景。
In order to solve the problem of non-contact and high-precision non-destructive testing of aircraft composite components, a laser-based ultrasonic testing system and a photoacoustic parameter matching method are proposed. The layered composite model was established by finite element method, and the asymmetry distribution, beam tilt and distortion characteristics of laser ultrasonic were analyzed and calculated by laminar anisotropy. With the experimental analysis, the photoacoustic parameter matching method. In the system design, the Nd: YAG pulsed laser with 1 064 nm wavelength is used to excite the ultrasonic wave, and the ultrasonic signal is detected by the double-wave hybrid interferometry system based on the photorefractive effect. The excitation and detection laser are guided by the optical fiber and projected onto the surface of the workpiece , A precision six-axis articulated robot was used as a C-type scanning device to establish a systematic laboratory prototype. The C-type scanning of the carbon / epoxy composite sample was detected, and the distribution, shape and size characteristics of the simulated defects in the sample were obtained. Verify the effectiveness of the detection system and parameter matching method. The results show that the developed robot-assisted laser ultrasonic inspection system can detect and image the stratified layer with a diameter of 1 mm or more inside the carbon / epoxy composites and has potential applications in the non-destructive testing of aircraft composite materials.