Inspecting for widespread fatigue damage: Is partial debonding the key?

Experimental and analytical results indicate that cracks can initiate, grow, and coalesce more rapidly in fuselage lap joints that have experienced partial or complete debonding. Computational analysis in this paper shows that stress concentrations and stress intensity factors at the rivet holes are far less severe when the bond is intact. Debonding hastens the initiation of widespread fatigue cracks and significantly increases crack growth rate. Thus, debonded regions serve as "breeding grounds" for widespread fatigue damage. Therefore, the effectiveness of lap joint inspection programs may be enhanced if detailed inspections are focused on areas in which debonding has been detected.