Effect of hygrothermal aging in distilled and saline water on the mechanical behaviour of mixed short fibre/woven composites

In this paper, we investigate the effect of hygrothermal aging in different media on the mechanical behaviour of mixed short fibre/woven composite laminates. We study composite laminates made up of 4 plies of fiberglass fabrics (Mat 300 g/m2, Mat 450 g/m2, Taffetas 800 g/m2) and unsaturated polyester resins, which are realised by contact moulding. In order to properly characterize our materials and to understand the phenomena responsible for modifying their behaviour, various physico-chemical and mechanical tests are carried out on composite laminates with and without a gel coat. The main aim of our study is to determine the mechanical properties, e.g. ultimate stress, yield strength and flexural modulus, of the laminates through three-point bending tests, under the effect of hygrothermal aging in aggressive environments, i.e. distilled water and saline water at different time intervals, and high temperature. In order to follow the physico-chemical evolutions and their influences on the mechanical properties of the composite laminates, a comparative study of the properties is carried out for both unaged and aged specimens. The analysis of all obtained results shows that aging time, medium and temperature have a significant influence on the mechanical behaviour of mixed short fibre/woven composites.