Hedayatrasa Saeid, Segers Joost, Poelman Gaétan, Paepegem Wim Van, Kersemans Mathias
Mechanics of Materials and Structures (UGent-MMS), Department of Materials, Textiles and Chemical Engineering (MaTCh), Ghent University, Technologiepark-Zwijnaarde 46, 9052 Zwijnaarde, Belgium.
SIM Program M3 DETECT-IV, Technologiepark-Zwijnaarde 48, 9052 Zwijnaarde, Belgium.
Materials (Basel). 2021 May 7;14(9):2436. doi: 10.3390/ma14092436.
This paper proposes an efficient non-destructive testing technique for composite materials. The proposed vibro-thermal wave radar (VTWR) technique couples the thermal wave radar imaging approach to low-power vibrothermography. The VTWR is implemented by means of a binary phase modulation of the vibrational excitation, using a 5 bit Barker coded waveform, followed by matched filtering of the thermal response. A 1D analytical formulation framework demonstrates the high depth resolvability and increased sensitivity of the VTWR. The obtained results reveal that the proposed VTWR technique outperforms the widely used classical lock-in vibrothermography. Furthermore, the VTWR technique is experimentally demonstrated on a 5.5 mm thick carbon fiber reinforced polymer coupon with barely visible impact damage. A local defect resonance frequency of a backside delamination is selected as the vibrational carrier frequency. This allows for implementing VTWR in the low-power regime (input power < 1 W). It is experimentally shown that the Barker coded amplitude modulation and the resultant pulse compression efficiency lead to an increased probing depth, and can fully resolve the deep backside delamination.
本文提出了一种用于复合材料的高效无损检测技术。所提出的振动热波雷达（VTWR）技术将热波雷达成像方法与低功率振动热成像相结合。VTWR通过对振动激励进行二相调制来实现，使用5位巴克码编码波形，随后对热响应进行匹配滤波。一维解析公式框架证明了VTWR具有高深度分辨率和更高的灵敏度。所得结果表明，所提出的VTWR技术优于广泛使用的经典锁相振动热成像。此外，在一块5.5毫米厚的碳纤维增强聚合物试样上对VTWR技术进行了实验演示，该试样有几乎不可见的冲击损伤。选择背面分层的局部缺陷共振频率作为振动载波频率。这使得VTWR能够在低功率状态下（输入功率<1W）实现。实验表明，巴克码编码幅度调制和由此产生的脉冲压缩效率导致探测深度增加，并且能够完全分辨深层背面分层。
