Abstract

In the presented study, by applying analytical methods and using experimental data, equations are achieved to predict the fatigue life of unidirectional carbon fiber/epoxy composite (UCFEC) that is applied in aerospace structures. The experimental data used to obtain these equations are achieved by low earth orbit (LEO) environment simulation experiment and other experiments. By employing convex curves analytical method, some equations to predict the fatigue life of unidirectional carbon fiber/epoxy composite in LEO are achieved. Then, by inspiration of convex curves method, steady-linear method to predict the fatigue life of unidirectional carbon fiber/epoxy composite on Mars is proposed. Furthermore, the results of convex curves method have proved that the main factor causing fracture of UCFEC in vacuum thermal cycles is the degradation of inter laminar shear strength between the carbon fiber and epoxy. Finally, the results obtained by these methods are compared with the results from other experiments of composite materials. The comparison showed that the results of this study seem acceptable.

Key words: Fatigue life prediction, unidirectional carbon fiber, composite, earth orbit, Mars.