Browsing by Author "Dimopoulos, A."

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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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    ItemOpen Access
    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.