Contribution à l’étude de la fatigue des matériaux composites SMC

Contribution to the study of the fatigue behaviour of SMC composites

¹ Doctorant ;
² Maître de conférence ;
³ Chargé de Recherches CNRS ;
⁴ Professeur Département Matériaux-Mécanique Physique, URA 447 Ecole Centrale de Lyon , Ecully

Abstract

The fatigue behaviour of Sheet Moulding Composites (SMC) has been investigated under a flexural loading. It has been shown that a classical three-points bending test performed under deflection control was well suited to the characterisation of the fatigue behaviour of SMC materials. Nevertheless, the stiffness evolution of SMC during fatigue is very complex and the lifetime criterions usually used for unidirectional composites are no more valid for SMC. A new lifetime criterion has been thus developed on the basis of a detailed analysis of damage mechanisms during fatigue life.

Complementary damage indicators such as superficial microscopic analysis, acoustic-emission and damping capacity were used in addition to stiffness measurements. The derived lifetime criterion presents a simple mechanical meaning and corresponds to a transition from microscopic damage nucleation to macroscopic damage propagation.