MIMICKING ARTIFICIAL NEURAL NETWORKS IN PREDICTING THE RESIDUAL STRENGTH OF PRE-FATIGUED GFRP LAMINATES THROUGH ACOUSTIC EMISSION ANALYSIS

The acoustic emission activity generated in monotonic four-point bending tests by pre-fatigued glass fibre-reinforced plastic specimens was treated by a conventional interpolation method, with the aim to predict the material residual strength. From the numerical analysis, a three-constant empirical model was derived, by which the residual strength was predicted as a function of the applied stress and the associated cumulative number of acoustic emission events. The results obtained were compared with those discussed in a previous work, where the same scope was pursued by the application of artificial neural networks. The response of the two methods was practically the same, in terms of both mean values and scatter. It was concluded that the classical interpolation may be preferable in the case examined, because the artificial intelligence approach required considerably longer times in the selection of the best network configuration

MECHANICAL PROPERTIES OF FIBRE REINFORCED PLASTIC OBTAINED USING COLD PLASMA TREATED FIBRES

Monotonic tensile tests were carried out on four types of composite materials, reinforced with polyester, polyethylene, aramid and glass fibres, respectively. Before fabrication, the reinforcement was superficially exposed to cold plasma, varying the exposure time. From the monotonic tests a beneficial effect of plasma on the modulus was noted in the case of aramid and glass

EFFECT OF COLD PLASMA SURFACE TREATMENT ON MECHANICAL PROPERTIES OF FIBRE REINFORCED PLASTICS

In this works, a glow discharge cold plasma treatment was employed to treat organic and inorganic fibre (aramid , polyethylene and glass fibres) with the aim to improve the fibre-matrix interface properties. In order to quantitatively assess the effect of plasma treatment, treated and untreated fibres were used to fabricate specimens suitable for mechanical test characterisation. Peeling test and three-point bending tests were performed on untreated and treated specimens. Scanning electron microscopy was utilised to examine the plasma effects on the fibres surface and on the specimen fracture surfaces. The results obtained indicate that the interface strength depends of both the fibre type and the treatment time. In all cases, an increase in delamination energy was observed under appropriate treatment conditions. SEM analysis had shoved variation in the fibres roughens Although this last result, the measured Young’s modulus and flexural strength do not undergo any decrease, whichever the exposure tim