激光剪切散斑干涉与红外成像复合的无损检测新方法与设备试制

Shearography and thermography are non-contacting optical techniques, which provide full-field information for detecting material defects in specific metallic, nonmetallic and composites materials. They have become valuable tools for material nondestructive evaluation since they are easy to apply in various working circumstances. However, the methods are fundamentally different in their flaw detection mechanisms. Shearography measures the mechanical response of a material to stress, whereas active thermography measures the heat-transfer response of a material to thermal excitation. In this investigation, the coupling technique of shearography and thermography is explored for the feasibility of a combined means for non-destructive evaluation. The purpose is to develop an integrated portable instrument which possesses the advantages of two kinds of detection methods. It is quite significant to achieve fast, non-contact measurement and improve the performance of the image based non-destructive method. This research will be deployed in the following aspects. First, the key techniques in shearography, which include the development of long-life PZT driven phase shifter and the corresponding temporal real-time phase shifting algorithm, will be studied. This technique can notably improve the sensitivity of shearography in identifying flaws. The research is followed by the study of image processing methods on improving the detection precision in the sequential thermographic images when the object surface is subjected to a pulsed or periodic thermal excitation. Polynomial fitting and fast Fourier transform algorithms will be considered. Then the image analyzing methods coupling shearographic and thermographic images will be studied in order to quantitatively reveal internal local damage (e.g., flaws). The integrated instrument for non-destructive evaluation will be designed based on the novel techniques developed with shearography and thermography. By developing parallel computing algorithms, the live thermal image and the interferometric phase image will be displayed in real-time on the same screen during inspection. And the internal defects will be quantitatively identified with new algorithm according to the 2 types of images. Samples such as fiber reinforced polymer, honeycombs, laminated composites, and fiber reinforced pressure vessels will be prepared. By comparing the results with those obtained from C scan and other radiation detection methods, the functions of the newly developed equipment will be enriched and the performance will be improved with modification of the software.

激光剪切散斑干涉和红外成像无损检测技术具有非接触、全场测量的优点，然而在应用中各有局限性。本项目提出了研制复合型的激光剪切散斑干涉和红外成像无损检测设备的整体思路，充分发挥两种检测方法的优势，研制新型便携式无损检测设备。本项目拟开展热波在典型复合材料部件中传播的基础理论研究，探索缺陷所引起的物体表面温度变化和物体表面变形的机制；开展激光剪切散斑干涉和热成像无损检测关键技术研究，包括开展长寿命低电压压电陶瓷相移器开发和实时相移算法研究；探索提升检测灵敏度的红外序列图像处理方法；开展电子散斑干涉与红外复合的缺陷检测新方法研究；设计一体化激光剪切散斑干涉/红外成像无损检测设备，开发两种检测图像的共屏实时显示技术，研究结合两种图像的缺陷精确定位算法。最后，针对航空航天典型复合材料构件，开展新型检测设备的应用研究，通过与现有无损检测方法进行对比，积累新装备的应用经验，完善新装备的检测功能。

激光剪切散斑干涉和红外成像无损检测技术具有非接触、全场测量的优点，然而在应用中各有局限性。本项目提出了研制复合型的激光剪切散斑干涉和红外成像无损检测设备的整体思路，充分发挥两种检测方法的优势，研制新型便携式无损检测设备。本项目运用数值分析方法开展了热波在典型复合材料部件中传播的基础理论研究，探索缺陷所引起的物体表面温度变化和物体表面变形的机制，提出了基于长脉冲和锁相热激励加载条件下的红外序列图像位相分析方法；在激光剪切散斑干涉技术研究方面，研制了长寿命低电压压电陶瓷相移器和实时相移算法研究；运用深度学习技术开展了散斑缺陷自动识别技术研究，并提出了基于迈克尔逊干涉光路的大视场激光散斑干涉光路；探索了激光散斑和红外成像复合无损检测技术的新方法和融合技术，提高了非接触无损检测技术的检测能力。针对航空航天典型复合材料构件，开展新型检测设备的应用研究。