Paper number 887

DAMAGE MONITORING IN CFRP LAMINATES BY MEANS OF DIELECTRICAL PROPERTIES

J.C Abry¹,² A. Chateauminois¹, G. Giraud², C. Henaff-Gardin³, M.C. Lafarie-Frénot³ and M. Salvia¹

1Laboratoire d'Ingéniérie et Fonctionnalisation des Surfaces
Ecole Centrale de Lyon, BP 163, 69131 Ecully Cedex, France
2Laboratoire de Physique des Systèmes Désordonnés
IUSTI, Technopôle de Château Gombert, 13453 Marseille Cedex 13, France
3Laboratoire de Mécanique et Physique des Matériaux
ENSMA, BP 109, Téléport 2, Futuroscope, 86960 Poitiers, France

Summary

Damage development in CFRP laminates subjected to quasi-static loading has been monitored by means of dielectrical measurements. Cross-ply and angle ply laminates have been subjected to bending stresses, while continuously recording the real (Z') and the complex (Z") components of the impedance. The results showed that both Z' and Z" were affected by transverse cracking during the early stages of the loading. These results were interpreted by considering that cracking is able to modify both the resistive and the capacitive components of the dielectrical response. Changes in Z' were related to the disruption of conducting paths between adjacent fibres, whereas changes in Z" were attributed to void formation in the cracked composite. By means of X-ray radiography, it was possible to establish a relationship between the progressive increase in crack density and the relative changes in Z' and Z".

Keywords

CFRP laminates, damage monitoring, dielectric properties, intralaminar cracking, delamination.