Browsing by Author "Kissinger, Thomas"
Now showing 1 - 20 of 46
Results Per Page
Sort Options
Item Open Access 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.Item Open Access 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, StephenRefer 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.Item Open Access 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, StuartTechnologies 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.Item Open Access Characterisation of a cryostat using simultaneous, single-beam multiple-surface laser vibrometry(American Institute of Physics Publishing, 2016-06-28) Kissinger, Thomas; Charrett, Thomas O. H.; James, Stephen W.; Adams, Alvin; Twin, Andrew; Tatam, Ralph P.A novel range-resolved interferometric signal processing technique that uses sinusoidal optical frequency modulation is applied to multi-surface vibrometry, demonstrating simultaneous optical measurements of vibrations on two surfaces using a single, collimated laser beam, with a minimum permissible distance of 3.5 cm between surfaces. The current system, using a cost-effective laser diode and a fibre-coupled, downlead insensitive setup, allows an interferometric fringe rate of up to 180 kHz to be resolved with typical displacement noise levels of 8 pm · Hz−0 5. In this paper, the system is applied to vibrometry measurements of a table-top cryostat, with concurrent measurements of the optical widow and the sample holder target inside. This allows the separation of common-mode vibrations of the whole cryostat from differential vibrations between the window and the target, allowing any resonances to be identified.Item Open Access Correction of periodic displacement non-linearities by two-wavelength interferometry(IOP, 2021-08-31) Bridges, Angus; Yacoot, Andrew; Kissinger, Thomas; Humphreys, David A.; Tatam, Ralph P.Non-linearities in interferometric displacement measurements commonly affect both homodyne and heterodyne optical interferometers. Unwanted back reflections (ghost reflections) or polarisation leakage introduce non-linearity terms at harmonics of the illuminating wavelength that cannot be fully corrected for with standard non-linearity correction techniques. A two-wavelength interferometric approach, operating at 632.8 and 785 nm, is presented here that is capable of correcting such non-linearities. Non-linearities are separated from the difference between two displacement measurements made at differing wavelengths with a Fourier approach. Compared to a standard Heydemann ellipse fitting correction, the proposed approach reduces estimated residual non-linearities from 84 to 11 pm in the case of a linear displacement profile. In particular this approach is applicable to the correction of higher order non-linearities that are caused by multiple reflections, and that are therefore very sensitive to alignment conditions.Item Open Access Correction of periodic displacement non-linearities by two-wavelength interferometry - associated data(Cranfield University, 2021-08-23 10:26) Bridges, Angus; Yacoot, Andrew; Kissinger, Thomas; Humphreys, David; Tatam, RalphData associated with the publication "Correction of periodic displacement non-linearities by two-wavelength interferometry".Item Open Access Cost-effective vibration and displacement measurement using range-resolved interferometry(British Society for Strain Measurement’s (BSSM), 2015-09-03) Kissinger, Thomas; Charrett, Thomas O. H.; James, Stephen W.; Tatam, Ralph P.A recently developed range-resolved optical interferometric signal processing technique is applied to vibration and displacement sensing with fibre-based beam delivery. The technique is demonstrated to allow the simultaneous acquisition of high-quality, high resolution relative displacement measurements (ߪ ൌ ͵ ) based on interferometric phase evaluation along with coarser ሺߪ ൌ ͲǤͲͷ ) absolute displacement measurements. The interferometric relative displacement data can be used for vibrometry measurement and to yield high-quality derivative velocity and acceleration data suitable for position control applications. The absolute data can serve as an additional proximity sensor. The sensing approach employs cost-effective diode lasers, off-the-shelf digital processing hardware and a very simple optical setup, and can, due to the use of a collimated beam, operate over a wide range of working distances.Item Open Access 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, RalphEach 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.Item Open Access Data supporting "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, SimonEach 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.Item Open Access 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, RalphFSI_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.Item Open Access Data supporting: 'Fibre-optic measurement of strain and shape on a helicopter rotor blade during a ground run: data for the measurement of strain'(Cranfield University, 2022-09-01 15:49) James, Stephen; Kissinger, Thomas; Weber, Simone; Mullaney, Kevin; Chehura, Edmon; Barrington, James; Tatam, RalphFBG_Data_CORD.csv contains the raw wavelength data from the 10 FBGs (G1-G10) recorded during the ground run detailed within the paper "Fibre-optic measurement of strain and shape on a helicopter rotor blade during a ground run - part 1: measurement of strain", James et al. Smart Materials and Structures, available online, May 2022. The unit of the "Time" column is seconds, while the units of columns G1-G10 are nanometers. FSI_Data_CORD.csv contains the raw phase data obtained from the interferometers formed between the reflectors (R1-R10,) and the cleaved end of the optical fibre, recorded during the ground run detailed within the paper The unit of the "Time" column is seconds, while the units of columns R1-R10 are radians.Item Open Access Dynamic fiber-optic shape sensing using fiber segment interferometry(Cranfield University, 2017-09-14 09:16) Kissinger, Thomas; Chehura, Edmond; E. Staines, Stephen; W. James, Stephen; P. Tatam, RalphResearch Data for Paper "Dynamic fibe- optic shape sensing using fiber segment interferometry" by Thomas Kissinger, Edmond Chehura, Stephen E. Staines, Stephen W. James and Ralph P. Tatam, Cranfield University, UKItem Open Access Dynamic fiber-optic shape sensing using fiber segment interferometry(IEEE, 2017-09-12) Kissinger, Thomas; Chehura, Edmond; Staines, Stephen E.; James, Stephen W.; Tatam, Ralph P.Dynamic fiber-optic shape sensing, often also referred to as curvature or bend sensing, is demonstrated using fiber segment interferometry, where chains of fiber segments, separated by broadband Bragg grating reflectors, are interrogated using range-resolved interferometry. In this work, the theory of interferometric curvature sensing using fiber segments is developed in detail, including techniques to infer lateral displacements from the measured differential strain data and methods for directional calibration of the sensor. A proof-of-concept experiment is performed, where four fiber strings, each containing four fiber segments of gauge length 20 cm each, are attached to the opposing sides of a flexible support structure and the resulting differential strain measurements are used to determine the lateral displacements of a 0.8 m cantilever test object in two dimensions. Dynamic tip displacement measurements at 40nm . HZ-0.5 noise levels over a 21 kHz bandwidth demonstrate the suitability of this approach for highly sensitive and cost-effective fiber-optic lateral displacement or vibration measurements.Item Open Access Fiber segment interferometry for dynamic strain measurements(Cranfield University, 2017-07-21 15:25) Kissinger, Thomas; O. H. Charrett, Thomas; W. James, Stephen; P. Tatam, Ralph; Correia, RicardoResearch Data for Paper: Thomas Kissinger, Ricardo Correia, Thomas O. H. Charrett, Stephen W. James and Ralph P. Tatam, "Fiber segment interferometry for dynamic strain measurements" Journal of Lightwave Technology 34.19 (2016): 4620-4626Item Open Access A fibre optic angle sensing tape for applications in robotics and automation(SPIE, 2023-08-15) Pillai, Sivaji; Charrett, Thomas O. H.; Kissinger, Thomas; James, Stephen W.; Tatam, Ralph P.A dual-fibre single-plane angle-sensing tape that utilizes optical Fibre Segment Interferometry and Range- Resolved Interferometry (RRI) for angle sensing is presented. The sensing tape facilitates the multiplexing of an array of angle sensors along its length and can be retrofitted into small robots and construction equipment. We demonstrate its application on three non-rotational joints of a small five-axis robot, describing the design, construction, measurement principle, and presenting measurement results. Preliminary data shows that the angles measured by the sensing tape exhibited agreement within a range of ±0.005° with the manufacturer-installed angle encoder of the robot.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 Fibre segment interferometry using code-division multiplexed optical signal processing for strain sensing applications(Iop Publishing Ltd, 2013-09-30T00:00:00Z) Kissinger, Thomas; Charrett, Thomas O. H.; Tatam, Ralph P.A novel optical signal processing scheme for multiplexing fibre segment interferometers is proposed. The continuous-wave, homodyne technique combines code-division multiplexing with single-sideband modulation. It uses only one electro-optic phase modulator to achieve both range separation and quadrature interferometric phase measurement. This scheme is applied to fibre segment interferometry, where a number of long-gauge length interferometric fibre sensors are formed by subtracting pairs of signals from equidistantly placed, weak back reflectors. In this work we give a detailed account of the signal processing involved and, in particular, explore aspects such as electronic bandwidth requirements, noise, crosstalk and linearity, which are important design considerations. A signal bandwidth of ±20 kHz permits the resolution of phase change rates of 2.5 × 104 rad s-1 for each of the four 16.5 m long segments in our setup. We show that dynamic strain resolutions below 0.2 nanostrain Hz-0.5 at 2 m sensor gauge length are achievable, even with an inexpensive diode laser. When used in applications that require only relative strain change measurements, this scheme compares well to more established techniques and can provide high-fidelity yet cost-effective measurements.Item Open Access Fibre-coupled, multiplexed methane detection using range-resolved interferometry(Institute of Physics, 2021-02-08) Bremner, James; Kissinger, Thomas; Hodgkinson, Jane; Tatam, Ralph P.We describe the first use of range-resolved interferometric signal processing for measurement of spectral transmission. This was applied to gas sensing using tunable diode laser spectroscopy, allowing the simultaneous and independent measurement of methane concentrations in multiple gas cells. The system uses a single injection-current modulated diode laser and a single photodetector. For three gas cells, we show the ability of the system to measure methane at noise equivalent concentrations of less than 200 ppm for a 0.5 s measurement period and a potential noise equivalent concentration (1σ) of <20 ppm with 150 s averaging time. We further show that cross-talk between cells is below the experimental uncertainty for the systemItem Open Access Fibre-optic measurement of strain and shape on a helicopter rotor blade during a ground run: 1. Measurement of strain(IOP Publishing, 2022-06-08) James, Stephen W.; Kissinger, Thomas; Weber, Simone; Mullaney, Kevin; Chehura, EdmondOptical fibre strain and shape measurement sensors were deployed on a 5-m long rotor blade during a full-speed (rotation rate 6.6 Hz) helicopter ground run, with real-time data wirelessly streamed from rotor hub-mounted sensor interrogators. In Part 1 of a 2-part paper series, the strain sensing capabilities of the two optical fibre-based sensing techniques, optical fibre Bragg grating (FBG) and fibre segment interferometry (FSI), are compared, while Part 2 (Kissinger et al 2022 Smart Mater. Struct. accepted) specifically investigates the blade shape measurement based on the FSI approach. In part 1, the rotor hub-mounted instrumentation is described, and data on the dynamics of the blade obtained from a sequence of controlled pilot inputs are analysed both in the time and spectral domains. It is shown that this can provide insights into the aeroelastic properties of the blade. Noise standard deviations of 0.2 n√ ε/ Hz and 30 nε/ Hz for the FSI and FBG-based sensing approaches, respectively, were observed over a strain range of 3500 µepsilon.Item Open Access High sensitivity pressure measurement using optical fibre sensors mounted on a composite diaphragm(Cranfield University, 2021-01-21 17:44) James, Stephen; Aime, Laura; Kissinger, Thomas; Chehura, Edmon; Tatam, RalphData underlying the work presented in the paper "High sensitivity pressure measurement using optical fibre sensors mounted on a composite diaphragm", published in Optics Express, 2020. Each zip file contains the data and a text file describing the contents. Full details are provided in the paper
- «
- 1 (current)
- 2
- 3
- »