【论文】微宏观裂纹分布式光纤感知：基于界面断裂能模型

【研究背景】

社会上的一些问题，例如建筑物的安全性和桥梁的耐久性，需要使用新的技术来解决。然而，目前的研究领域存在一个挑战，即如何准确地测量裂纹的大小和数量。这是一个重要的问题，因为它可以帮助人们预测材料的寿命和安全性，并采取必要的措施来保护人们的生命和财产。

【研究内容】

本研究旨在解决裂纹量化的问题。研究人员通过进行板分裂试验，探究了裸光纤和其涂层层之间的界面剪切应力-滑移关系。基于此，他们提出了一种基于界面断裂能的分析模型，将界面剪切应力-滑移关系转换为微观和宏观裂纹的COD。研究人员通过板分裂试验和文献中的实验数据验证了模型的准确性。此外，他们还利用四点梁试验的实验结果研究了模型在多裂纹情况下的可行性。模型辅以应变叠加策略，在界面剥离之前精确量化多个裂纹的COD，但在界面剥离之后则失败了。此外，他们还提出了一种基于裂开长度和相应COD之间线性关系的简化方法，便于评估剥离后的COD。

【研究意义】

本研究提出了一种新的方法，可以更准确地测量裂纹的大小和数量。这种方法可以应用于建筑物、桥梁等结构的监测和维护，有助于预测材料的寿命和安全性，并采取必要的措施来保护人们的生命和财产。此外，该研究还提出了一种简化方法，使得COD的评估更加容易和高效。这些创新点都具有重要的研究意义和应用价值。

来源：Structural Health Monitoring

作者：Lin, Shaoqun, Tan, Daoyuan, Jian-Hua, Yin, Zhu, Honghu, Yong, Kong

机构：香港理工大学，南京大学

DOI：10.1177/14759217231215482

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Distributed fiber optic sensing for micro- and macro-crack quantification: an interfacial-fracture-energy-based model

Authors: Shao-Qun Lin, Dao-Yuan Tan, Jian-Hua Yin, Hong-Hu Zhu, Yong Kong

Affiliations: Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; School of Earth Sciences and Engineering, Nanjing University, Nanjing, China

[Abstract] Clarifying the strain transfer between the host material with a crack opening displacement (COD) and the optical fiber after interfacial debonding remains a critical challenge for crack quantification. The interfacial debonding induced a triangular form strain profile around the crack due to the residual shear stresses at the interface. This study investigated the interfacial shear stress-slip relationship between the bare fiber and its coating layer through a plate splitting test. Based on that, we proposed an interfacial-fracture-energy-based analytical model to convert distributed fiber optic strains before and after interfacial debonding to CODs of micro- and macro-cracks. The accuracy of the model under a single crack was validated through plate splitting tests and the experimental data reported in the literature. Furthermore, experimental results from a four-point beam test were utilized to investigate the feasibility of the model under multiple cracks. The model, assisted by the strain superposition strategy, accurately quantified the CODs of multiple cracks before interfacial debonding but failed when interfacial debonding occurred. In addition, we proposed a simplified method based on the linear relationship between the debonded lengths and the corresponding CODs, which facilitates evaluation of the CODs after debonding.

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