Influence of riveting die configuration and squeeze force on the mechanical properties and fatigue behavior of aircraft lap joints

Riveting is the predominant method of joining metal sheets, especially for pressurized aircraft fuselages. In this paper, the effect of riveting die configuration and squeeze force on the mechanical properties and fatigue behavior of riveted joints was investigated systematically. The rivet head dimensions and interference distribution were obtained by the riveting test. The microstructure morphology was characterized by metallographic experiments that illuminate the deformation mechanism of the riveting process. The variation law of shear load and pull-out load with riveting die configuration under different squeeze forces was revealed by quasi-static experiments. Using fatigue test explored the relationship between the riveting process and fatigue life. The fatigue fracture mechanism was revealed by analyzing the fracture morphology and fretting wear, which was detected by SEM and EDS. The results showed that the riveting die configuration has little effect on the shear strength, but has significant attributes on the pull-out strength. The average fatigue life of a flat head riveting die specimen is higher than the concave head riveting die specimen. Under the same riveting die configuration, the average fatigue life increased with the growth of squeeze force. The riveted joints made by flat head riveting die were suitable for shear load and fatigue load, while the riveted joints processed by concave head riveting die had significant advantages under pull-out load.