Browsing by Author "Buggy, Stephen J."

Now showing 1 - 8 of 8
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    Composite material process monitoring using optical fibre grating sensors
    (Cranfield University, 2008-06) Buggy, Stephen J.; Tatam, Ralph P.; James, Stephen W.
    In this thesis a long period grating (LPG) based sensor is investigated as a possible alternative to current process monitoring sensors used in the manufacture of composites to monitor cure. An LPG is demonstrated as a means of monitoring the cure of a UVcured epoxy resin. The wavelength shift of the attenuation bands were measured during the cure of the resin and compared with measurements made using a fibre optic Fresnel based refractometer. The results showed a good correlation (6 x 10 -3 rius) and illustrate the potential of the techniques for non-invasive composite material cure monitoring. Alternative fibre grating methods; a chirped LPG sensor, an in-fire Mach-Zehnder interferometer and a tilted fibre Bragg grating sensor, are also presented to demonstrate the versatility of grating based sensors for flow, high sensitivity refractive index and multi-parameter sensing, respectively. Demonstrations of LPG sensors in industrial applications are also presented and highlight the technical issues of integrating such devices in composite components and composite manufacturing processes.
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    Cure monitoring of a UV cured epoxy resin using a long period grating Mach- Zehnder interferometer
    (International Society for Optical Engineering; 1999, 2007-12-31T00:00:00Z) Buggy, Stephen J.; Murphy, Richard P.; James, Stephen W.; Tatam, Ralph P.; Cutolo, A.; Culshaw, B.; Lpez-Higuera, J. M.
    A cascaded long period grating Mach-Zehnder interferometer is used to monitor the change in refractive index of a UV cured epoxy resin over a cure cycle. Fourier techniques are used to calculate the phase shift and frequency spectral amplitude of the associated fringe pattern during the cure. The results are compared with the refractive index change during cure calculated using a Fresnel reflection based technique.
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    Fibre grating refractometer sensors for composite process monitoring
    (2007-06-17T00:00:00Z) Buggy, Stephen J.; Chehura, Edmon; Skordos, Alexandros A.; Dimopoulos, A.; James, Stephen W.; Partridge, Ivana K.; Tatam, Ralph P.; Osten, W.; Gorecki, C.; Novak, E. L.
    Optimum performance from advanced composites requires careful control of the resin matrix during cure. This is to ensure there are no cure induced voids and to minimise the build up of internal stresses. Careful control of the process is also necessary to reduce wastage. Traditional resin inspection techniques are bulk or sample oriented and thus cannot provide data about critical component parts. Optical fibre based sensors however, allow for in-situ monitoring techniques to be deployed in components without effecting their structural integrity. In this work, two fibre optic grating techniques are demonstrated as process monitoring sensors and are compared with a Fresnel refractometric method. The change in refractive index of a resin has previously been used as a means for assessing the degree of cure. The central wavelength of an attenuation band of a long period grating (LPG) was monitored during the cure of a resin. In parallel the spectral resonances of a tilted fibre Bragg grating (FBG) are also monitored. The two techniques are shown to correlate well with the Fresnel based method in both detecting the resin and monitoring the state of cure, indicating the potential of the techniques for online production monitoring
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    A long period grating based directional flow sensor
    (International Society for Optical Engineering; 1999, 2008-12-31T00:00:00Z) Buggy, Stephen J.; James, Stephen W.; Tatam, Ralph P.
    A chirped long period grating (LPG) is used as a directional flow sensor by monitoring the change in the transmission spectrum upon immersion in an oil of refractive index higher than that of the fibre cladding. The change in profile of an attenuation band is shown to depend on the direction of immersion, indicating the possibility of using such devices in applications such as resin flow sensing in the manufacture of fibre reinforced plastic composite structures.
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    Monitoring cure in epoxies containing carbon nanotubes with an optical-fiber fresnel refractometer
    (John Wiley & Sons, Ltd, 2009-07-15T00:00:00Z) Dimopoulos, A.; Buggy, Stephen J.; Skordos, Alexandros A.; James, S. W.; Tatam, Ralph P.; Partridge, Ivana K.
    Fresnel refractometry was used to follow the changes in the refractive index during the isothermal curing of a simple difunctional epoxy resin, a commercial formulated multifunctional epoxy blend, and the same two resin systems modified by the addition of multiwalled carbon nanotubes. The refractive index change, monitored via an embedded optical fiber, was correlated with the degree of cure established from isothermal differential scanning calorimetry measurements. A good correlation was established in all cases, indicating the potential of the technique to be used for online cure monitoring in thermosetting resin carbon nanocomposites.
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    Multi-component strain development in superconducting magnet coils monitored using fibre Bragg grating sensors fabricated in highly linearly birefringent fibre
    (Institute of Physics, 2011-12-31T00:00:00Z) Chehura, Edmon; Buggy, Stephen J.; James, Stephen W.; Johnstone, Adam; Lakrimi, M’hamed; Domptail, Fred; Twin, Andrew; Tatam, Ralph P.
    The commissioning of superconducting magnet coils was monitored using embedded optical fibre Bragg grating sensors (FBG) fabricated in highly linearly birefringent (HiBi) fibre. The HiBi FBG sensors monitored the internal strain developed in the coils during the energization of the coils. The development of multiple components of strain in the coils when the magnet was energized and quenched was monitored, revealing phenomena that it had not been previously possible to measure using other sensor technologies.
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    Optical Fibre Grating Refractometers for Resin Cure Monitoring.
    (Institute of Physics, 2007-06-01T00:00:00Z) Buggy, Stephen J.; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P.
    The use of fibre grating refractometers as a means of monitoring the cure of a UVcured epoxy resin is presented. The wavelength shift of the attenuation bands of a long period grating and the spectral response of a tilted fibre Bragg grating sensor were measured simultaneously during the cure of the resin and compared with measurements made using a fibre optic Fresnel based refractometer. The results showed a good correlation (6 x 10 -3 rius) and illustrate the potential of the techniques for non-invasive composite material cure monitoring.
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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.