Repeat scanning technology for laser ultrasonic propagation imaging
Repeat scanning technology for laser ultrasonic propagation imaging
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DOI：
10.1088/0957-0233/24/8/085201
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发表时间：
2013-06
影响因子：
2.4
通讯作者：
Jung‐Ryul Lee;S. Y. Chong;Nitam Sunuwar;Chan Yik Park
中科院分区：
文献类型：
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作者：
Jung‐Ryul Lee;S. Y. Chong;Nitam Sunuwar;Chan Yik Park
激光超声扫描结合接触式或非接触式传感器为大型复合材料结构的结构健康管理（SHM）和非破坏性过程质量控制（IPQC）提供了新的范例。基于激光超声扫描和定点传感的波传播成像技术显示出显著的优势，例如在SHM中对嵌入式传感器的需求最小，在IPQC中的最小侵入性缺陷可视化以及弯曲和复杂目标检测的一般能力，以及时间无参考检测。然而，与其他SHM方法和基于超声的非破坏性评估一样，信噪比（SNR）是真实的结构应用中普遍存在的问题，特别是对于非接触薄复合材料传感或厚且异质的复合材料。提出了一种用于激光超声传播成像（UPI）技术的高速重复扫描技术，该技术利用调Q连续波激光器1 kHz的扫描速度，精确控制激光束脉冲实现同点扫描。因此，该技术能够实现显着改善的SNR检查现实世界的复合材料结构。所提出的技术提供了增强的结果，在2毫米厚的机翼盒的碳纤维增强塑料制成的冲击损伤检测，尽管非接触式激光超声传感的灵敏度低。采用激光多普勒测振仪作为非接触式超声传感器，研制了一种现场应用的纯激光UPI系统。所提出的技术使剥离缺陷的可视化在15 mm厚的风叶片试样由玻璃纤维增强塑料制成，尽管在厚的复合材料的超声波的高耗散。
Laser ultrasonic scanning in combination with contact or non-contact sensors provides new paradigms in structural health management (SHM) and non-destructive in-process quality control (IPQC) for large composite structures. Wave propagation imaging technology based on laser ultrasonic scanning and fixed-point sensing shows remarkable advantages, such as minimal need for embedded sensors in SHM, minimum invasive defect visualization in IPQC and general capabilities of curved and complex target inspection, and temporal reference-free inspection. However, as with other SHM methods and non-destructive evaluation based on ultrasound, the signal-to-noise ratio (SNR) is a prevalent issue in real structural applications, especially with non-contact thin-composite sensing or with thick and heterogeneous composites. This study proposes a high-speed repeat scanning technique for laser ultrasonic propagation imaging (UPI) technology, which is realized with the scanning speed of 1 kHz of a Q-switched continuous wave laser, and precise control of the laser beam pulses for identical point scanning. As a result, the technique enables the achievement of significant improvement in the SNR to inspect real-world composite structures. The proposed technique provides enhanced results for impact damage detection in a 2 mm thick wing box made of carbon-fiber-reinforced plastic, despite the low sensitivity of non-contact laser ultrasonic sensing. A field-applicable pure laser UPI system has been developed using a laser Doppler vibrometer as the non-contact ultrasonic sensor. The proposed technique enables the visualization of the disbond defect in a 15 mm thick wind blade specimen made of glass-fiber-reinforced plastic, despite the high dissipation of ultrasound in the thick composite.