Identification of the Non-linear Behaviour a 4D Carbon–Carbon Material Designed for Aeronautic Application

The global mechanical behaviour of a 4D carbon–carbon (C– C 4D) composite material is described. Designed for aeronautic applications and particularly for the brake discs of heavy air craft, this material is a layered composite reinforced in three directions in the plane (−60°, 0°, 60°) to which the fourth direction of reinforcement is perpendicular. Having ascertained the compliance matrices in the plane to which the braking surface is parallel, we have determined the engineering constants of an elementary ply from the basic assumptions of the classical laminations theory (CLT). Finally, to construct both linear-elastic and elastoplastic constitutive equations of the C– C 4D, we propose a thermodynamic model that accurately characterises the behaviour of this material. This simple model can be identified from simple mechanical tests.