Residual modulus degradation model for woven fabric composite determined by impulse excitation technique

Abstract

Structural components in the aircraft industries often require geometries that induce stress concentration effects, intensifying fatigue phenomena. When combined with a lack of structural monitoring it may limit composite applications. This research focuses on stiffness reduction of a notched carbon fiber laminate subjected to tension-tension fatigue load. The stiffness reduction was monitored during the cyclic tests by the use of the impulse excitation technique. Three major degradation stages were observed, the initial stage showed a high degradation rate followed by constant modulus degradation. The last stage was related to the presence of extensive delamination occurring outside of the notch area.