A coupled analysis of mechanical behaviour and ageing for polymer-matrix composites

The use of organic-matrix composites for long lifetime aeronautics applications leads to a study of the coupling effects between thermo-mechanical stresses and thermal ageing. Taking into account the effects of oxidation in a behaviour law requires first, an understanding of every mechanism of degradation and the interactions between them. The objective of this paper is to present current studies of these subjects and, in particular, our own approach, in order to include oxidation in a macroscopic behaviour law. For the oxidation section, studies have led to establishment of kinetics of thermal-oxidation for several polymer matrixes. For the mechanical section, a visco-elastic model coupled with damage is presented and allows to obtain the multiaxial creep behaviour of any composite laminate from few short-time tests conducted on elementary laminates.