Get smart, go optical: example uses of optical fibre sensing technology for production optimisation and subsea asset monitoring

Fiber Bragg grating (FBG) measuring bolts, as a useful tool to evaluate the behaviors of steel bolts in underground engineering, can be manufactured by gluing the FBG sensors inside the grooves, which are usually symmetrical cuts along the steel bolt rod. The selection of the cut shape and the glue types could perceivably affect the final supporting strength of the bolts. Unfortunately, the impact of cut shape and glue type on bolting strength is not yet clear. In this study, based on direct tension tests, full tensile load–displacement curves of rock bolts with different groove shapes were obtained and analyzed. The effects of groove shape on the bolt strength were discussed, and the stress redistribution in the cross-section of a rock bolt with different grooves was simulated using ANSYS. The results indicated that the trapezoidal groove is best for manufacturing the FBG bolt due to its low reduction of supporting strength. Four types of glues commonly used for the FBG sensors were assessed by conducting tensile tests on the mechanical testing and simulation system and the static and dynamic optical interrogators system. Using linear regression analysis, the relationship between the reflected wavelength of FBG sensors and tensile load was obtained. Practical recommendations for glue selection in engineering practice are also provided.

Section: Introductionmentioning

confidence: 99%

Study on the Optimal Groove Shape and Glue Material for Fiber Bragg Grating Measuring Bolts

Zhao

Zhang

et al. 2018

“…The stability of resistance strain gauge is poor. The phenomenon of zero drift readily occurs in the process of using resistance strain gauges, and there is a sizeable residual strain in repeated measurements [32]. Moreover, some problems were encountered during in situ applications, including (i) corrosive groundwater and dusty circumstances causing failure of mechanical and electronic sensors, (ii) electronic sensors which were susceptible to electromagnetic interference, (iii) that monitoring of data collection relies on laborious manual operations, and (iv) implementation of real-time and remote monitoring was difficult [33].…”

Section: Fbg Sensormentioning

confidence: 99%

Testing Mechanical Properties of Rock Bolt under Different Supports Using Fiber Bragg Grating Technology

Guo

Wang

et al. 2019

Fiber Bragg grating (FBG) sensors, which can accurately measure strain, can be integrated with rock bolts with small fingerprints. In this paper, according to the force mechanism of prestressed anchor and non-prestressed anchor, different loading modes were designed, named active loading mode and passive loading mode. Then, FBG technology was used to monitor the axial force variation of prestressed anchor and non-prestressed anchor in different loading modes. Based on the test results, it is found that when the anchoring force is relatively small (<35 kN), prestressed anchors need to be tested by active loading mode, and non-prestressed anchors need to be tested by passive loading mode. For the prestressed anchor, the force condition of the bolt-shaft was similar to that of the two-force bar, and the axial force of the bolt-shaft was nearly the same along its entire length. Taking the applied load as the reference, the change rate of the axial force of the bolt-shaft was less than 10%. For non-prestressed anchor, due to the plate, there is a certain area surrounding the plate where the axial force of the bolt-shaft was greatly influenced. With applied loads of less than 15 kN, the change rate of the axial force on FBG1 was greater than 10%. With applied loads of greater than 20 kN, this was less than 10%. In this area, influenced by the plate, the axial force of the bolt-shaft increases, and as the applied load of the pullout test increases, the influence decreases.

“…In recent years, given the unique characteristics of high accuracy, excellent electromagnetic immunity, durability, and distributed measurement, a new sensor, based on fiber Bragg grating (FBG) material as a perceived element and transmission medium, has been widely applied in a variety of industries, such as civil engineering, petroleum engineering, and structural engineering [4,5,6,7,8], especially in harsh environments [9,10]. FBG monitoring in underground engineering has been conducted by many researchers.…”

Section: Introductionmentioning

confidence: 99%

A Fiber Bragg Grating-Based Monitoring System for Roof Safety Control in Underground Coal Mining

Zhao

Zhang

2016

Monitoring of roof activity is a primary measure adopted in the prevention of roof collapse accidents and functions to optimize and support the design of roadways in underground coalmines. However, traditional monitoring measures, such as using mechanical extensometers or electronic gauges, either require arduous underground labor or cannot function properly in the harsh underground environment. Therefore, in this paper, in order to break through this technological barrier, a novel monitoring system for roof safety control in underground coal mining, using fiber Bragg grating (FBG) material as a perceived element and transmission medium, has been developed. Compared with traditional monitoring equipment, the developed, novel monitoring system has the advantages of providing accurate, reliable, and continuous online monitoring of roof activities in underground coal mining. This is expected to further enable the prevention of catastrophic roof collapse accidents. The system has been successfully implemented at a deep hazardous roadway in Zhuji Coal Mine, China. Monitoring results from the study site have demonstrated the advantages of FBG-based sensors over traditional monitoring approaches. The dynamic impacts of progressive face advance on roof displacement and stress have been accurately captured by the novel roadway roof activity and safety monitoring system, which provided essential references for roadway support and design of the mine.