Abstract

Detection of cracks while at their early stages of evolution is important in health monitoring of civil structures. Review of technical literature reveals that single or sparsely distributed multiple cracks can be detected by Brillouin-scattering-based optical fiber sensor systems. In a recent study, a pre-pump-pulse Brillouin optical time-domain analysis (PPP-BOTDA) system was employed for detection of a single microcrack. Specific characteristics of the Brillouin gain spectrum, such as Brillouin frequency shift, and Brillouin gain spectrum width, were utilized in order to detect the formation and growth of microcracks with crack opening displacements as small as 25 μm. In most situations, formations of neighboring microcracks are not detected due to inherent limitations of Brillouin-based systems. In the study reported here, the capability of PPP-BOTDA for detection of two neighboring microcracks was investigated in terms of the proximity of the microcracks with respect to each other, i.e., crack spacing distance, crack opening displacement, and the spatial resolution of the PPP-BOTDA. The extent of the study pertained both to theoretical as well as experimental investigations. The concept of shape index is introduced in order to establish an analytical method for gauging the influence of the neighboring microcracks in detection and microcrack differentiation capabilities of Brillouin-based optical fiber sensor systems.

© 2016 Optical Society of America

Detection and monitoring of surface micro-cracks by PPP-BOTDA

Dewei Meng, Farhad Ansari, and Xin Feng
Appl. Opt. 54(16) 4972-4978 (2015)

Strain-induced vibration and temperature sensing BOTDA system combined frequency sweeping and slope-assisted techniques

Junhui Hu, Lan Xia, Li Yang, Wenwen Quan, and Xuping Zhang
Opt. Express 24(12) 13610-13620 (2016)

Evaluation of the accuracy of BOTDA systems based on the phase spectral response

Alexia Lopez-Gil, Marcelo A. Soto, Xabier Angulo-Vinuesa, Alejandro Dominguez-Lopez, Sonia Martin-Lopez, Luc Thévenaz, and Miguel Gonzalez-Herraez
Opt. Express 24(15) 17200-17214 (2016)

Distributed measurement of dynamic strain based on multi-slope assisted fast BOTDA

Dexin Ba, Benzhang Wang, Dengwang Zhou, Mingjing Yin, Yongkang Dong, Hui Li, Zhiwei Lu, and Zhigang Fan
Opt. Express 24(9) 9781-9793 (2016)

1200°C high-temperature distributed optical fiber sensing using Brillouin optical time domain analysis

Pengbai Xu, Yongkang Dong, Dengwang Zhou, Cheng Fu, Juwang Zhang, Hongying Zhang, Zhiwei Lu, Liang Chen, and Xiaoyi Bao
Appl. Opt. 55(21) 5471-5478 (2016)