Effect of Straight-Sunk and Counter-Sunk Rivet Hole in Plate Subjected to Cyclic Loading

摘要

Mechanically secure joints, such as pinned, riveted or bolted joints, are widely used to assemble primary structure components, both metallic and composite. The greatest advantage of using riveted joints in a lightweight aerospace structure is that they are stronger and more durablethan any other joints such as welded joints. Mechanical fasteners are frequently used for a variety of reasons, and one has to evaluate the consequences of such a design decision: fastener holes drilled in the composite structures produce sudden discontinuities, disrupt the fiber flow, andact as stress concentration. Unique attention can be given to creating stress-free holes by designing local reinforcement; damage-free holes can be also manufactured with special tooling. The stress concentration at a hole edge is one of main causes of the shortening of crack initiation lifeof a riveted plate when cyclic stress was applied. In the present study, to enhanced the fatigue life of a riveted plate which uses countersunk head rivets, the shape of the countersink and the rivet head were improved. The corner of the root of the countersink was rounded, and stress concentrationat that point was reduced. The experimental results showed that the fatigue life of the riveted plate was improved where the improved rivet was used. The crack intiation site observed on the fracture surface of the holed specimen in which the improved rivet hole was drilled was different fromthat in which a normal rivet hole was drilled.