Sea water aging of glass reinforced composites:: Shear behaviour and damage modelling

This paper presents results from a study of the wet aging of four thermoset resins and their [0 degrees /90 degrees] 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 degreesC sea water, 50 degreesC sea water and 50 degreesC distilled water. Tensile tests, on resins and at 45 degrees 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.