Abstract:

Three accelerated ageing conditions of salt spray,ultraviolet and hygrothermal are tested on the composite of aircraft structures. The cycle acceleration experimental parameters are established. The hygroscopic law of different accelerated ageing cycles is analysised and the tensile mechanical properties are studied. The fracture mode and fracture morphology are observed. The results show that the hygroscopic capacity after 5 accelerated ageing cycles in accordance with Fick's second law. With the accelerated aging cycle carrying on,the maximum tensile strength and the failure mode are gradually decreased. The descent rate is fast in the beginning and slow in the late stage and finally stabilized. They are inversely proportional to moisture absorption. After the ultraviolet light irradiation the sample surface is gradually losing its luster. The colour is changed from white to dark brown and the resin is photoaging. The types of the fracture mainly include debonding between fiber and matrix.

Key words: composite materials, cycle acceleration ageing, salt spray ageing, ultraviolet ageing, hygrothermal ageing