Thermo-mechanical characterisation of in-plane properties for CSM E-glass epoxy polymer composite materials – Part 2: Young's modulus

In-situ Curing Strain Monitoring of a Flat Plate Residual Stress Specimen Using a Chopped Stand Mat Glass/Epoxy Composite as Test Material

“…This is in an acceptable agreement with previous measured gelation (61 %) using DMA, with the red dot in Fig. 6 representing the result taken from [28] and matching the kink of the FBG 4 Neat . The thermal expansion/contraction behaviour of the neat CSM glass/epoxy material has previously been suggested to follow a bi-linear model with its transition temperature equal to the instantaneous T g of the material [27].…”

“…This type of mat was chosen such comparison with earlier data could be done [27,28]. The CSM fibre mat has an area weight of 450 g/m 2 and the approximate chopped fibre bundle length is 50 mm.…”

“…A cure and temperature representation of the Young's Modulus for CSM glass/epoxy may be found in [28]. Figure 3 illustrates the time evolution of the Imaginary Impedance Maximum (IIM) during the process.…”

“…The suppression of the bi-linear behaviour for the residual stress specimens is attributed to the presence of the steel plate which governs the expansion/contraction [20] behaviour during the process. The transition temperature (76°C) identified during cooling of the neat material is compared with the T g model [28].…”

“…Impedance spectroscopy is utilised to characterise insitu the matrix material state and a linear extrapolation of the thermal contribution of the imaginary impedance maximum signal is suggested. Process milestones and phenomena such as resin gelation, vitrification, chemical shrinkage and thermal expansion are assessed and set against earlier data [27,28], in which the neat material behaviour was characterised. Moreover, it is shown that the proposed specimen configuration is able to induce curing stresses and the technique can be applied to fibrous composites.…”