Experimental Analysis of Debonding of Skin/Stringer Interfaces under Cyclic Loading and Ageing

An experimental investigation aiming to characterize the fatigue failure mechanisms and effect of ageing of skin/stringer interfaces is presented. A simplified specimen known as a “stringer foot specimen” is used. The effects of local design, of the angle of plies located at the interface and of moisture ageing are studied. Among other results, it is shown that a quasiinfinite fatigue life can be obtained under 33% of the static damage initiation load for all designs. In the framework of multilevel analysis, this study is a preliminary investigation to study cyclic buckling of composite stiffened structures.