Tabatabaeian Ali, Mohammadi Reza, Harrison Philip, Fotouhi Mohammad
James Watt School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK.
Faculty of Civil Engineering and Geosciences, Delft University of Technology, 2628 CN Delft, The Netherlands.
Sensors (Basel). 2024 Aug 10;24(16):5170. doi: 10.3390/s24165170.
Traditional inspection methods often fall short in detecting defects or damage in fibre-reinforced polymer (FRP) composite structures, which can compromise their performance and safety over time. A prime example is barely visible impact damage (BVID) caused by out-of-plane loadings such as indentation and low-velocity impact that can considerably reduce the residual strength. Therefore, developing advanced visual inspection techniques is essential for early detection of defects, enabling proactive maintenance and extending the lifespan of composite structures. This study explores the viability of using novel bio-inspired hybrid composite sensors for detecting BVID in laminated FRP composite structures. Drawing inspiration from the colour-changing mechanisms found in nature, hybrid composite sensors composed of thin-ply glass and carbon layers are designed and attached to the surface of laminated FRP composites exposed to transverse loading. A comprehensive experimental characterisation, including quasi-static indentation and low-velocity impact tests alongside non-destructive evaluations such as ultrasonic C-scan and visual inspection, is conducted to assess the sensors' efficacy in detecting BVID. Moreover, a comparison between the two transverse loading types, static indentation and low-velocity impact, is presented. The results suggest that integrating sensors into composite structures has a minimal effect on mechanical properties such as structural stiffness and energy absorption, while substantially improving damage visibility. Additionally, the influence of fibre orientation of the sensing layer on sensor performance is evaluated, and correlations between internal and surface damage are demonstrated.
传统的检测方法在检测纤维增强聚合物(FRP)复合结构中的缺陷或损伤时往往存在不足,随着时间的推移,这可能会损害其性能和安全性。一个典型的例子是由平面外载荷(如压痕和低速冲击)引起的几乎不可见的冲击损伤(BVID),这种损伤会显著降低残余强度。因此,开发先进的视觉检测技术对于早期发现缺陷、实现主动维护以及延长复合结构的使用寿命至关重要。本研究探讨了使用新型生物启发式混合复合传感器检测层压FRP复合结构中BVID的可行性。从自然界中发现的变色机制中汲取灵感,设计了由薄层玻璃和碳层组成的混合复合传感器,并将其附着在承受横向载荷的层压FRP复合材料表面。进行了全面的实验表征,包括准静态压痕和低速冲击试验以及诸如超声C扫描和视觉检测等无损评估,以评估传感器检测BVID的功效。此外,还对静态压痕和低速冲击这两种横向载荷类型进行了比较。结果表明,将传感器集成到复合结构中对结构刚度和能量吸收等力学性能的影响最小,同时显著提高了损伤的可见性。此外,还评估了传感层纤维取向对传感器性能的影响,并证明了内部损伤与表面损伤之间的相关性。