Browsing by Author "Correia, Ricardo N."
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Item Open Access Development and application of optical fibre strain and pressure sensors for in-flight measurements(IOP Publishing, 2016-09-16) Lawson, Nicholas J.; Correia, Ricardo N.; James, Stephen W.; Partridge, Matthew; Staines, Stephen E.; Gautrey, James E.; Garry, Kevin; Holt, Jennifer C.; Tatam, Ralph P.Fibre optic based sensors are becoming increasingly viable as replacements for traditional flight test sensors. Here we present laboratory, wind tunnel and flight test results of fibre Bragg gratings (FBG) used to measure surface strain and an extrinsic fibre Fabry–Perot interferometric (EFFPI) sensor used to measure unsteady pressure. The calibrated full scale resolution and bandwidth of the FBG and EFFPI sensors were shown to be 0.29% at 2.5 kHz up to 600 με and 0.15% at up to 10 kHz respectively up to 400 Pa. The wind tunnel tests, completed on a 30% scale model, allowed the EFFPI sensor to be developed before incorporation with the FBG system into a Bulldog aerobatic light aircraft. The aircraft was modified and certified based on Certification Standards 23 (CS-23) and flight tested with steady and dynamic manoeuvres. Aerobatic dynamic manoeuvres were performed in flight including a spin over a g-range −1g to +4g and demonstrated both the FBG and the EFFPI instruments to have sufficient resolution to analyse the wing strain and fuselage unsteady pressure characteristics. The steady manoeuvres from the EFFPI sensor matched the wind tunnel data to within experimental error while comparisons of the flight test and wind tunnel EFFPI results with a Kulite pressure sensor showed significant discrepancies between the two sets of data, greater than experimental error. This issue is discussed further in the paper.Item Open Access Evaluation of the optical switching characteristics of erbium-doped fibres for the development of a fibre Bragg grating sensor interrogator(SPIE, 2014-06-02) Rigas, E.; Correia, Ricardo N.; Stathopoulos, N. A.; Savaidis, S. P.; James, Stephen W.; Bhattacharyya, Debabrata; Kirby, Paul B.; Tatam, Ralph P.A polling topology that employs optical switching based on the properties of erbium-doped fibres (EDFs) is used to interrogate an array of FBGs. The properties of the EDF are investigated in its pumped and un-pumped states and the EDFs’ switching properties are evaluated by comparing them with a high performance electronically controlled MEM optical switch. Potential advantages of the proposed technique are discussed. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.Item Open Access Fibre Bragg grating based effective soil pressure sensor for geotechnical applications(International Society for Optical Engineering; 1999, 2009-12-31T00:00:00Z) Correia, Ricardo N.; Li, Jin; Staines, Stephen E.; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P.; Kutner, Joel; Dewhurst, Paul; Ferreira, PedroAn effective-soil-pressure sensor for geotechnical applications based on Fibre Bragg Gratings is presented. The sensor simultaneous measures total soil pressure and pore pressure, allowing the calculation of the effective stress of soil. Calibration of the sensor using pressurised air demonstrated a pressure sensitivity of 2.02x10 ± 2.84x10nm/kPa and 1.87x10 ± 6.88x10nm/kPa for the total and pore pressure respectively. This corresponds to a pressure resolution of 4.95x10 kPa and 5.46x10kPa for total and pore pressure using a 1pm interrogation system. Measurements undertaken in two types of soil demonstrated dependence of the total pressure sensitivity on soil density/stiffness. Pore pressure measurements agreed well with the preliminary calibratioItem Open Access A fibre Bragg grating based inclinometer system for ground movement measurement(International Society for Optical Engineering; 1999, 2010-12-31T00:00:00Z) Li, Jin; Correia, Ricardo N.; Chehura, Edmon; Staines, Stephen E.; James, Stephen W.; Tatam, Ralph P.The measurement of ground movement is an essential part of many geotechnical engineering operations. For decades, inclinometer systems have traditionally been used for this purpose to provide crucial information to engineers and researchers. However, conventional inclinometer systems have their limitations, such as high cost and poor durability. In this paper a fibre optic based inclinometer system is reported, which utilizes fibre Bragg grating sensors attached to the casing of a conventional inclinometer. The characterization of the sensor revealed good agreement with theory and conventional displacement measurements. For a casing of length 2.5 m, the minimum measureable deflection of the top of the casing was found to be 0.48 mm when the FBGs were interrogated with a 1 pm wavelength resolution system.Item Open Access Fibre segment interferometry for dynamic strain measurements(Institute of Electrical and Electronics Engineers, 2016-02-18) Kissinger, Thomas; Correia, Ricardo N.; Charrett, Thomas O. H.; James, Stephen W.; Tatam, Ralph P.Using a novel range-resolved interferometric signal processing technique based on the sinusoidal optical frequency modulation of a cost-effective laser diode, a fibre sensing approach termed fibre segment interferometry (FSI) is described. In FSI, a chain of long-gauge length fibre optic strain sensors are separated by identical in-fibre partial reflectors. Targeted at dynamic strain analysis and ultrasound detection for structural health monitoring, this approach allows integrated strain measurements along fibre segments, removing the sensing gaps and sensitivity to inhomogeneities found with localized fibre sensors. In this paper, the multiplexing of six fibre segments, each of length 12.5 cm, is demonstrated. The sensor array can be interrogated at 98 kHz data rate, achieving dynamic strain noise levels 0:14 n Hz 0:5. The reflector fabrication is discussed, an analysis of linearity and noise performance is carried out and results from an exemplar experiment to determine the speed-of-sound of a stainless steel rod are shown.Item Open Access Highly sensitive contact pressure measurements using FBG patch in endotracheal tube cuff(SPIE, 2016-05-31) Correia, Ricardo N.; Blackman, O. R.; Hernandez, F. U.; Korposh, Sergiy; Morgan, S. P.; Hayes-Gill, R.; James, Stephen W.; Evans, D.; Norris, A.A method for measuring the contact pressure between an endotracheal tube cuff and the trachea was designed and developed by using a fibre Bragg grating (FBG) based optical fibre sensor. The FBG sensor is encased in an epoxy based UV-cured cuboid patch and transduces the transversely loaded pressure into an axial strain that induces wavelength shift of the Bragg reflection. The polymer patch was created by using a PTFE based mould and increases tensile strength and sensitivity of the bare fibre FBG to pressure to 2.10×10-2 nm/kPa. The characteristics of the FBG patch allow for continuous measurement of contact pressure. The measurement of contact pressure was demonstrated by the use of a 3D printed model of a human trachea. The influence of temperature on the measurements is reduced significantly by the use of a second FBG sensor patch that is not in contact with the trachea. Intracuff pressure measurements performed using a commercial manometer agreed well with the FBG contact pressure measurements. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.Item Open Access Interrogation of fibre Bragg gratings through a fibre optic rotary joint on a geotechnical centrifuge(SPIE, 2016-05-31) Correia, Ricardo N.; James, Stephen W.; Marshall, Alec; Heron, Charles; Korposh, SergiyThe monitoring of an array of fibre Bragg gratings (FBGs) strain sensors was performed through a single channel, single mode fibre optic rotary joint (FORJ) mounted on a geotechnical centrifuge. The array of three FBGs was attached to an aluminum plate that was anchored at the ends and placed on the model platform of the centrifuge. Acceleration forces of up to 50g were applied and the reflection signal of the monitored FBGs recorded dynamically using a 2.5kHz FBG interrogator placed outside the centrifuge. The use of a FORJ allowed the monitoring of the FBGs without submitting the FBG interrogator to the high g-forces experienced in the centrifuge. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.Item Open Access Locally pressed fibre Bragg grating pressure sensor(2006-12-31T00:00:00Z) Correia, Ricardo N.; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P.A spectral-hole created by locally pressing a fibre Bragg grating exhibited a wavelength-shift within the FBG bandwidth. A sensitivity of 74.3pm/(N/mm) was obtained for pressure applied along the slow axis of a high birefringence fibre.Item Open Access Range-resolved signal processing for fibre segment interferometry applied to dynamic long-gauge length strain sensing(SPIE, 2015-11) Kissinger, Thomas; Correia, Ricardo N.; Charrett, Thomas O. H.; James, Stephen W.; Tatam, Ralph P.A range-resolved interferometric signal processing technique using sinusoidal optical frequency modulation is applied to fibre segment interferometry. Here, six optical fibre segments of gauge length 12.5 cm are used as interferometric strain sensors and are formed between seven weak, broadband fibre Bragg gratings, acting as in-fibre partial reflectors. In a very simple and cost-effective optical setup using injection current modulation of a laser diode source, interferometric measurement of acoustic wave propagation in a metal rod is used to demonstrate the capabilities of the technique.