Extraction and processing of real time strain of embedded FBG sensors using a fixed filter FBG circuit and an artificial neural network
- Authors: Kahandawa, Gayan , Epaarachchi, Jayantha , Wang, Hao , Canning, John , Lau, Alan
- Date: 2013
- Type: Text , Journal article
- Relation: Measurement: Journal of the International Measurement Confederation Vol. 46, no. 10 (2013), p. 4045-4051
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- Description: Fibre Bragg Grating (FBG) sensors have been used in the development of structural health monitoring (SHM) and damage detection systems for advanced composite structures over several decades. Unfortunately, to date only a handful of appropriate configurations and algorithm sare available for using in SHM systems have been developed. This paper reveals a novel configuration of FBG sensors to acquire strain reading and an integrated statistical approach to analyse data in real time. The proposed configuration has proven its capability to overcome practical constraints and the engineering challenges associated with FBG-based SHM systems. A fixed filter decoding system and an integrated artificial neural network algorithm for extracting strain from embedded FBG sensor were proposed and experimentally proved. Furthermore, the laboratory level experimental data was used to verify the accuracy of the system and it was found that the error levels were less than 0.3% in predictions. The developed SMH system using this technology has been submitted to US patent office and will be available for use of aerospace applications in due course. © 2013 Elsevier Ltd. All rights reserved.
An application of near infra-red fibre bragg grating as dynamic sensor in SHM of thin composite laminates
- Authors: Zohari, Mohd , Kahandawa, Gayan , Epaarachchi, Jayantha , Lau, Alan , Cook, Kevin , Canning, John
- Date: 2013
- Type: Text , Conference paper
- Relation: Structural health monitoring 2013 : a roadmap to intelligent structures : proceedings of the 9th International Workshop on Structural Health Monitoring p. 267-275
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- Description: Vibration testing is an essential component in Structural Health Monitoring (SHM). It can provide vital information regarding the integrity of critical structure; for instance, it can provide information on progressive failure monitoring of composites structure in the aerospace industry. Over the past decade, there have been many successful researches showing extraordinary ability of Fiber Bragg grating (FBG) sensors as a dynamic sensor. Ability of acquiring both static and dynamic strain measurements, make FBG sensor as a good alternative to replace the conventional vibration sensors. In addition the physical size of FBG sensor provides greater access to embed them in composite structures without affecting to any properties of the composite. However, in most applications to date, people have used only the FBG with wavelength 1550 nm. Moreover, FBG sensors with this wavelength are commonly use in industries such as telecommunications and medical industries. However, there is an option of using near infra-red (NIR) FBG range which comparably cheap in term of total system design. This paper details the use of near infra-red (NIR) FBGs as dynamic sensors; a part of SHM system for the monitoring of the damages in a thin glass fiber composite plates. Results reveal that the NIR FBG range gives good response to an impact and; also to applied high frequency vibrations.
Development of embedded FBG sensors for SHM systems
- Authors: Kahandawa, Gayan , Epaarachchi, Jayantha , Canning, John , Gand-Ding, Peng , Lau, Alan
- Date: 2016
- Type: Text , Book chapter
- Relation: Structural health monitoring technologies and next-generation smart composite structures Chapter 3 p. 61-88
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Estimation of strain of distorted FBG sensor spectra using a fixed FBGfilter circuit and an artificial neural network
- Authors: Kahandawa, Gayan , Epaarachchi, Jayantha , Lau, Alan , Canning, John
- Date: 2013
- Type: Text , Conference paper
- Relation: 2013 IEEE 8th International Conference on Intelligent Sensors, Sensor Networks and Information Processing: Sensing the Future, ISSNIP 2013 p. 89-94
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- Description: Fibre Bragg Grating (FBG) sensors are extremely sensitive to changes of strain, and are therefore an extremely useful candidate for Structural Health Monitoring (SHM) systems of composite structures. Sensitivity of FBGs to strain gradients originating from damage was observed as an indicator of initiation and propagation of damage in composite structures. To date there have been numerous research works done on distorted FBG spectra due to damage accumulation under controlled environments. Unfortunately, a number of related unresolved problems remain in FBG-based SHM systems development, making the present SHM systems unsuitable for real life applications. This paper reveals a novel configuration of FBG sensors to acquire strain reading and an integrated statistical approach to analyse data in real time. The proposed configuration has proven its capability to overcome practical constraints and the engineering challenges associated with FBG-based SHM systems. A fixed filter decoding system and an integrated artificial neural network algorithm for extracting strain from embedded FBG sensor were proposed and experimentally proved. Furthermore, the laboratory level experimental data was used to verify the accuracy of the system and it was found that the error levels were less than 0.3% in strain predictions.
NIR fibre bragg grating as dynamic sensor : An application of 1D digital wavelet analysis for signal denoising
- Authors: Zohari, Mohd , Kahandawa, Gayan , Epaarachchi, Jayantha , Lau, Alan , Canning, John , Cook, Kevin
- Date: 2013
- Type: Text , Conference paper
- Relation: Fourth International Conference on Smart Materials and Nanotechnology in Engineering
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- Description: During the past decade, many successful studies have evidently shown remarkable capability of Fiber Bragg Gratings (FBG) sensor for dynamic sensing. Most of the research works utilized the 1550 nm wavelength range of FBG sensors. However near infra-red (NIR) FBG sensors can offer the lower cost of Structural health Monitoring (SHM) systems which uses cheaper silicon sources and detectors. Unfortunately, the excessive noise levels that experienced in NIR wavelengths have caused the rejection of sensor that operating in this range of wavelengths for SHM systems. However, with the appropriate use of signal processing tools, these noisy signals can be easily ‘cleaned’. Wavelet analysis is one of the powerful signal processing tools nowadays, not only for time-frequency analysis but also for signal denoising. This present study revealed that the NIR FBG range gave good response to impact signals. Furthermore, these ‘noisy’ signals’ response were successfully filtered using one dimensional wavelet analysis.
Distortion index for assessment of damage growth in a composite structures using spectral distortion of embedded FBG sensors
- Authors: Kahandawa, Gayan , Epaarachchi, Jayantha , Canning, John , Lau, Alan
- Date: 2013
- Type: Text , Conference paper
- Relation: 9th International Workshop on Structural Health Monitoring: A Roadmap to Intelligent Structures, IWSHM 2013 p. 175-181
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- Description: Structural Health Monitoring Systems based on embedded FBG sensors, to identify damage conditions, are largely dependent on the spectral distortion of the sensors. The uneven stress gradient occurring along the grating of FBG sensors, due to damage inside composite structures can be estimated by analyzing significant changes that appear in the FBG response spectra. However, the stochastic nature of the distorted shape of the FBG spectra makes it difficult to interpret and quantify the existing damage at the location of the FBG sensors. This research works on a novel concept of the "Distortion I ndex (DI)" which is defined using distorted spectra of FBG sensors. I t was observed that the DI increases with t he i ncrease in damage size.