Sea Water Aging of Glass Reinforced Composites: Shear Behaviour and Damage Modelling

Abstract

This paper presents results from a study of the wet aging of four thermoset resins and their [0°/90°] stitched glass fibre reinforced composites. The matrix resins are orthophthalic polyester, isophthalic polyester, vinyl ester and epoxy. Resins and composites were aged for 18 months, under three immersion conditions: 20°C sea water, 50°C sea water and 50°C distilled water. Tensile tests, on resins and at 45°to fibre direction of composites, both before and after aging enable the influence of matrix resin and aging medium on weight changes and matrix dominated property degradation to be evaluated. This has enabled a unique dataset to be obtained. A large part of the shear property loss after aging is recovered after drying. An original application of damage mechanics parameters is used to quantify the changes in composite shear behaviour, in order to provide a more complete representation of the inelastic response.

Immersed Fatigue Performance of Glass Fibre-Reinforced Composites for Tidal Turbine Blade Applications

“…However, it was realised that during high cycle fatigue testing (lasting a day or more) the coupons dry out due to the combination of internal heat generation and forced air cooling of the coupons. Allowing the coupons to dry out is not desirable as it has been shown [3] that epoxy and vinyl-ester composites recover most of their original strength when they are re-dried after water saturation. Two methods of keeping the samples immersed in water during the fatigue test, as shown in Figs.…”

“…Finally, it should be noted that it is very difficult to produce a barrier that can actually prevent diffusion of the small amount of moisture (1-2 %) required to saturate GFRP over the [10][11][12][13][14][15][16][17][18][19][20] year lifetime of these devices. Certainly the standard isophthalic polyester gelcoat is not capable of this level of performance [3]. For all these reasons, it is conservative to assume that immersed GFRP will become moisture-saturated relatively early in its life and it is therefore important for a designer to know what degradation in material properties can be expected over the life of the machine component.…”

“…Interlaminar shear strength (ILSS) and 45°off-axis tests are used as an indication of changes in interface bond strength and tests on GFRP laminates have shown reductions of 8 to 37 % after ageing in room temperature water [3,16]. Studies have shown that most of the bond strength recovers upon redrying the composite material, particularly when the initial loss in bond strength was due to high temperature ageing [3,17].…”

Sea Water Ageing of Composites for Ocean Energy Conversion Systems: Influence of Glass Fibre Type on Static Behaviour

“…More recently various authors have examined the influence of sea water on composite properties, e.g. [17][18][19][20]. Many other studies have focussed on the long term behaviour of composites in water, and a recent book provides an overview [21].…”

Carbon nanotube-reinforced glass fiber epoxy composite laminates exposed to hygrothermal conditioning

“…with respect to their durability and performance. Even today, this effort is an ongoing endeavor to develop or optimize composites for naval/oil-shore industry [6,8,[10][11][12][13][14][15][16][17][18]. One of the important observations reported in those studies reveals that during the initial stages of absorption, the water uptake follows Fick's Law [19][20][21] but on prolonged aging it no longer follows Fickian behavior.…”