Paper number 581

ULTRASONIC STUDY OF THE ANISOTROPIC DAMAGE OF UNIDIRECTIONAL GLASS-EPOXY COMPOSITES DURING HYGROTHERMAL AGEING

R. El Guerjouma, D. Ducret and J.C. Baboux

Groupe d'Etudes de Métallurgie Physique et de Physique des matériaux
GEMPPM UMR CNRS 5510 - INSA de Lyon -
20 Avenue Albert Einstein, 69621 Villeurbanne Cedex, France

Summary

The purpose of this work is to study using ultrasounds the effects of hygrothermal ageing on the elastic behaviour of an unidirectional glass-fibre reinforced epoxy matrix. Simulated ageing conditions are performed. The degradation processes resulting from 25 days ageing in distilled water at 70°C are considered. The damage is assessed quantitatively through the loss of stiffness in terms of elastic constants. In the framework of the thermodynamic of irreversible processes, a constitutive equation including a tensorial variable describing the damage phenomenon is used. Through the variation of the damage parameters, damage and its anisotropy are quantitatively assessed. This nondestructive characterization is conducted together with a SEM microstructural analysis to correlate ultrasonic macroscopic measurements to microscopic observations.

Keywords

elastic properties, non-destructive evaluation, ultrasonics, ageing, damage, anisotropy, interface, polymer composites.