Browsing by Author "Staines, Stephen"

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    All-electronic frequency stabilization of a DFB laser diode
    (Cranfield University, 2017-05-11 13:27) Asmari, Abdullah|Hodgkinson, Jane; Chehura, Edmon; Staines, Stephen; Tatam, Ralph
    Data to support the paper All-electronic frequency stabilization of a DFB laser diode A Asmari, J Hodgkinson, E Chehura, SE Staines and RP Tatam Optics Express 25 (10), 11679-11691, 2017. Doi: 10.1364/OE.25.011679
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    Application of fibre optic sensing systems to measure rotor blade structural dynamics
    (Elsevier, 2021-03-09) Weber, Simone; Kissinger, Thomas; Chehura, Edmond; Staines, Stephen; Barrington, James; Mullaney, Kevin; Fragonara, Luca Zanotti; Petrunin, Ivan; James, Stephen; Lone, Mudassir; Tatam, Ralph P.
    This paper compares two fibre optic sensing techniques for vibration characterisation: (a) optical fibre Bragg grating (FBG) strain gauges and (b) a novel direct fibre optic shape sensing (DFOSS) approach based on differential interferometric strain measurements between multiple fibres within the same fibre arrangement. Operational mode shapes and frequency measurements of an Airbus Helicopters H135 bearingless main rotor blade (5.1 m radius) were acquired during a series of ground vibration tests undertaken in a controlled laboratory environment. Data recorded by the fibre optic instrumentation systems were validated using commercially available accelerometers and compared against a baseline finite element model. Both fibre optic sensing systems proved capable of identifying the natural frequencies of the blade in the frequency range of interest (0–100 Hz). The data from the FBG sensors exhibited a dependency on their position relative to the neutral axes of the blade, which meant that full characterisation of the flapping and lagging modes required careful consideration of sensor location in the chordwise direction. The DFOSS system was able to identify all structural dynamics, despite being located on the neutral axis in the lagging direction, due to its sensitivity to angle changes, rather than strain, and its biaxial measurement capability. The DFOSS system also allowed the operational mode shapes of the blade to be determined directly, without the requirement for strain transfer from the blade to the sensor and without the requirement for a model of the underlying structure. The accuracy of obtained natural frequencies and operational mode shapes is assessed, demonstrating the potential of the use of both fibre optic sensing systems for determining blade structural dynamics.
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    Application of fibre optic sensing systems to measure rotor blade structural dynamics - underlying data
    (Cranfield University, 2021-03-12 09:17) James, Stephen; Kissinger, Thomas; Tatam, Ralph; Barrington, James; Chehura, Edmon; Weber, Simone; Mullaney, Kevin; Zanotti Fragonara, Luca; Petrunin, Ivan; Staines, Stephen
    Refer to the paper for full details. Fig9a.csv: Comparison of the Power Spectral Density (PSD) of data recorded by the direct optical fibre shape sensing system, an optical fibre Bragg grating strain sensor and a 1D accelerometer with finite element modeling predictions, measured on the top surface of an Airbus Helicopters H135 bearingless main rotor blade on the quarter chord line at approximately 40% rotor radius. Fig9b.csv: Comparison of the Power Spectral Density (PSD) of data recorded by the direct optical fibre shape sensing system, an optical fibre Bragg grating strain sensor and a 1D accelerometer with finite element modeling predictions, measured on the top surface of an Airbus Helicopters H135 bearingless main rotor blade on the quarter chord line at approximately 60% rotor radius. Fig10_FBG_top.csv: Power Spectral Density (PSD) of the 7th fibre Bragg grating strain (FBG) sensor (FBG7) in the three FBG arrays bonded to the top surface of the Airbus Helicopters H135 bearingless main rotor blade, located at approximately 60% rotor radius. Fig10_FBG_bottom.csv: Power Spectral Density (PSD) of the 7th fibre Bragg grating strain sensor (FBG7) in the three FBG arrays bonded to the bottom surface of the Airbus Helicopters H135 bearingless main rotor blade, located at approximately 60% rotor radius. Fig11.csv: Time series of raw data of 3F frequency input collected at approximately 60% rotor radius for the accelerometer, fibre Bragg grating strain sensor and direct optical fibre shape sensor (vertical direction). Fig12.csv: Comparison of Power Spectral Density (PSD) for the 3F mode measured at approximately 60% rotor radius by the accelerometer, fibre Bragg grating strain sensor and direct optical fibre shape sensor (vertical direction). Fig14.csv: Mode shapes measured using the direct optical fibre shape sensor Fig15.cvs: Comparison of normalised displacement mode shapes measured using a 1D accelerometer, the direct optical fibre shape sensor with the finite element model prediction Fig16.csv: Normalised angle measurements performed by the direct optical fibre shape sensor with the ouput from the FE model for Mode 5F Fig17.csv:Comparison of normalised strain mode shapes determined by the FBG strain sensors and the output from the FE model.
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    Bladesense – a novel approach for measuring dynamic helicopter rotor blade deformation
    (European Rotorcraft Forum, 2018-12-31) Weber, Simone; Southgate, Dominic; Mullaney, Kevin; James, Stephen; Rutherford, Robert; Sharma, Anuj; Lone, Mudassir; Kissinger, Thomas; Chehura, Edmond; Staines, Stephen; Pekmezci, Huseyin; Fragonara, Luca Zanotti; Petrunin, Ivan; Williams, Dan; Moulitsas, Irene; Cooke, Alastair; Rosales, Waldo; Tatam, Ralph P.; Morrish, Peter; Fairhurst, Mark; Atack, Richard; Bailey, Gordon; Morley, Stuart
    Technologies that allow accurate measurement of rotorblade dynamics can impact almost all areas of the rotorcraft sector; ranging from maintenance all the way to blade design. The BladeSense project initiated in 2016 aims to take a step in developing and demonstrating such a capability using novel fibre optic sensors that allow direct shape measurement. In this article the authors summarise key project activities in modelling and simulation, instrumentation development and ground testing. The engineering approach and associated challenges and achievements in each of these disciplines are discussed albeit briefly. This ranges from the use of computational aerodynamics and structural modelling to predict blade dynamics to the development of direct fibre optic shape sensing that allows measurements above 1kHz over numerous positions on the blade. Moreover, the development of the prototype onboard system that overcomes the challenge of transferring data between the rotating main rotor to the fixed fuselage frames is also discussed.
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    Data for: The use of range-resolved interferometry for multi-parameter sensing in a wind tunnel
    (Cranfield University, 2023-12-12 14:59) Barrington, James; James, Stephen; Kissinger, Thomas; Staines, Stephen; Alcusa Saez, Erica; Lawson, Nicholas; Tatam, Ralph; Prince, Simon
    Each data set relates to the data displayed in Figure 2 of the conference paper. The 1st column in each file outlines the data type and unit.
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    Data supporting "Optical Fibre Pressure Sensing Using a Frequency Modulated Laser-Based Signal Processing Technique"
    (Cranfield University, 2023-04-21 12:36) Barrington, James; James, Stephen; Kissinger, Thomas; Staines, Stephen; Prince, Simon; Alcusa Saez, Erica; Lawson, Nicholas; Tatam, Ralph
    Each file contains the relevant data to the figure as stated in its name. Column headers within the file outline the variable and its associated unit. The authors, where possible, have tried to keep the data in its rawest, useable form in order to provide the greatest flexibility for future manipulation. All data files are formatted as csv for accessibility.
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    Data supporting: 'Fibre-optic measurement of strain and shape on a helicopter rotor blade during a ground run: data for the measurement of shape'
    (Cranfield University, 2022-09-01 15:50) Kissinger, Thomas; James, Stephen; Weber, Simone; Mullaney, Kevin; Chehura, Edmon; Barrington, James; Staines, Stephen; Tatam, Ralph
    FSI_Phase_Data_Shape_CORD.csv contains the raw phase data from the three Fibre Segment interferometry array installed on the Direct Optical Fibre Shape Sensing Rod described in the paper: "Fibre-optic measurement of strain and shape on a helicopter rotor blade during a ground run - part 2: measurement of shape", Smart Materials and Structure, online 25 May 2022. Shape_Data_Vertical_CORD.csv contains the processed shape data in the vertical (flapping) direction, for the T&B2 ground run. Note that the position measurements are relative to the first FSI reflector on the rod, not to the centre of rotation of the blade. Shape_Data_Horizontal_CORD.csv contains the processed shape data n the horizontal (lagging) direction, for the T&B2 ground run. Note that the position measurements are relative to the first FSI reflector on the rod, not to the centre of rotation of the blade.
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    Monitoring the fabrication of tapered optical fibres
    (SPIE, 2017-04-23) Mullaney, Kevin; Correia, Ricardo; Staines, Stephen; James, Stephen W.; Tatam, Ralph P.
    A variety of optical methods to enhance the process of making optical fibre tapers are explored. A thermal camera was used to both refine the alignment of the optical components and optimize the laser power profile during the tapering process. The fibre transmission was measured to verify that the tapers had the requisite optical characteristics while the strain experienced by the fibre while tapering was assessed using an optical fibre Bragg grating. Using these techniques, adiabatic tapers were fabricated with a 2% insertion loss.
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    Optical fibre pressure sensing using a frequency modulated laser-based signal processing technique
    (IOP Publishing, 2023-04-21) Barrington, James; James, Stephen; Kissinger, Thomas; Staines, Stephen; Prince, Simon; Alcusa Saez, Erica; Lawson, Nicholas J.; Tatam, Ralph P.
    Range resolved interferometry (RRI) applied to the interrogation of an extrinsic Fabry–Perot based pressure sensor in laboratory and wind tunnel environments is presented. A simple, compact sensor head design was fabricated and subsequently characterised using RRI, which was shown to have a sensitivity of 1.627x10-3 rad Pa−1 with a noise standard deviation of 9 Pa over a data rate of 1.5 kHz. When installed in a high-lift wing for surface pressure evaluation during wind tunnel testing, the approach outlined here was able to perform as well as a conventionally employed commercial device for relative static pressure measurements.
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    Optimised process for fabricating tapered long period gratings
    (SPIE, 2017-04-23) Mullaney, Kevin; Staines, Stephen; James, Stephen; Tatam, Ralph P.
    The process of fabricating tapered long period gratings (TLPGs) using a CO2 laser is described. TLPGs with a period spacing of 378 μm, were fabricated by optimization of the taper waist diameter and careful control of the duty-cycle and its uniformity along the length of the grating. The 6-period TLPGs exhibited a pass-band insertion loss of 0.6 dB, resonance band extinction values of 3 dB and had a physical length of 2.27 mm.
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    Optimized process for fabricating ultra-short tapered long period gratings
    (IEEE, 2017-11-03) Mullaney, Kevin; Staines, Stephen; James, Stephen; Ralph, Tatam
    The process of fabricating tapered long period gratings (TLPGs) using a CO2 laser is described. The objective of this work is to optimize the CO2 laser based fabrication of TLPGs so that their transmission spectra are comparable with those made using the arc-discharge technique, which typically exhibits transmission losses below 2 dB. The losses currently observed with CO2 laser fabricated TLPGs are typically greater than 10 dB over the spectral waveband 650-1100 nm. In this work, the reduction in transmission loss was achieved by optimizing the micro-taper geometry and the duty-cycle of the device. TLPGs with a period of 378 μm were fabricated. The 6-period TLPGs exhibited a pass-band transmission loss of 0.6 dB, resonance band extinction values of 3 dB and had a physical length of 2.27 mm. The refractive index sensitivity of a 6 period TPLG was measured and found to be 372 nm/ RI.
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    Production process monitoring and post-production mechanical testing of a full-size carbon-fibre composite aircraft tailcone assembly using embedded optical fibre sensors
    (Cranfield University, 2021-02-22 17:04) James, Stephen; Tatam, Ralph; Staines, Stephen; Chehura, Edmon
    The spreadsheet contains the data underpinning the figures within the paper "Production process monitoring and post-production mechanical testing of a full-size carbon-fibre composite aircraft tailcone assembly using embedded optical fibre sensors", Edmon Chehura et al 2020 Meas. Sci. Technol. 31 105204.
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    Production process monitoring and post-production strain measurement on a full-size carbon-fibre composite aircraft tail cone assembly using embedded optical fibre sensors
    (IOP, 2020-07-13) Chehura, Edmon; James, Stephen W.; Staines, Stephen; Groenendijk, Chris; Cartié, Denis D. R.; Portet, Stephanie; Hugon, Michael; Tatam, Ralph P.
    Multiplexed optical fibre sensors were embedded into a carbon-fibre-reinforced-preform during the industrial production of a full-sized, one-piece tail cone assembly for a regional jet aircraft. Optical fibre Fresnel sensors monitored both the infusion of the resin, via measurement of the refractive index-dependent attenuation in the reflected light signal, and the degree of cure of the resin, via measurement of the chemical cure reaction-dependent change in refractive index. The resin cure was also monitored by optical fibre Bragg gratings (FBGs) fabricated in high linearly birefringent optical fibre, which measured through-thickness strain development, while FBGs in standard single mode optical fibre measured longitudinal strain development. The magnitudes and profiles of the transverse and longitudinal strains developed during the curing process were consistent across different locations on the tail cone. Typical transverse and longitudinal strains, related to cure reaction-induced shrinkage, were −1500 ± 17 μepsilon and −500 ± 5 μepsilon, respectively. Post-production, the same embedded FBG sensors were used subsequently to monitor structural strains when the tail cone was subjected to vacuum pressure loading. The longitudinal strains measured using the embedded FBG sensors were generally in good agreement with the longitudinal strains measured by the surface-bonded resistance foil strain gauge (RFSG) sensors, both qualitatively and quantitatively. The in-plane transverse and circumferential strains, oriented collinearly, were measured by the embedded FBGs and appropriately oriented surface-bonded RFSG sensors, respectively, and were, qualitatively, in good agreement
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    Railway track component condition monitoring using optical fibre Bragg grating sensors
    (2016-03-22) Buggy, Stephen J.; James, Stephen W.; Staines, Stephen; Carroll, R.; Kitson, P.; Farrington, D.; Drewett, L.; Jaiswal, J.; Tatam, Ralph P.
    The use of optical fibre Bragg grating (FBG) strain sensors to monitor the condition of safety critical rail components is investigated. Fishplates, switchblades and stretcher bars on the Stagecoach Supertram tramway in Sheffield in the UK have been instrumented with arrays of FBG sensors. The dynamic strain signatures induced by the passage of a tram over the instrumented components have been analysed to identify features indicative of changes in the condition of the components.
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    The use of range-resolved interferometry for multi-parameter sensing in a wind tunnel
    (SPIE, 2023-05-23) Barrington, James; James, Stephen; Kissinger, Thomas; Staines, Stephen; Prince, Simon; Alucsa-Saeza, Erica; Lawson, Nicholas J.; Tatam, Ralph P.
    The work presented demonstrates that key parameters in aerodynamic structural characterisation of pressure, strain, and structural dynamics, can be all measured via optical fibre sensors interrogated using the principles of range-resolved interferometry (RRI). When used to interrogate sensors simultaneously deployed on a high lift wind in a wind tunnel, the approach yielded resolutions of 31 μPa/ √ Hz and 1 nε/ √ Hz at a bandwidth of 1526 Hz for pressure and strain, respectively, demonstrating the accuracy and versatility of the RRI signal processing technique.
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    Wavelength-locking of a semiconductor laser using an electronic technique
    (SPIE, 2019-03-04) Mullaney, Kevin; Hodgkinson, Jane; Staines, Stephen; Tatam, Ralph P.
    This work describes a novel system to control the stability of a 1583 nm telecommunications laser diode via measurement of junction voltage. This electronic technique dispenses with the optical components used in conventional wavelength locking schemes and shifts wavelength control to system level electronic instrumentation. The approach employs real-time measurement of diode series resistance (Rs), which is used to compensate the measured forward voltage (Vf) and recover the junction voltage (Vj) of the laser. Control of Vj provides wavelength control without introducing a significant error when the package temperature varies. This was implemented by measuring Rs as the dynamic resistance, δV/δI, by modulating the injection current. Recent work has reduced the modulation amplitude and noise in the electronics. Using a frequency deviation of 1 GHz, we achieved a centre wavelength variation of ± 2 pm over a package temperature variation of 20-55 °C. This gives a wavelength/ temperature coefficient of 0.03 pm/ °C, which is an improvement on 0.34 pm/ °C, as typically achieved for optical locking systems. The system has been further developed using board-level components within a compact demonstrator unit. Work is on-going to further enhance this performance over a package temperature variation of 0-70 °C.