Effect of Squeezing Force on Stress and Fatigue of Aircraft Riveted Joints

This study investigated the effect of different squeezing forces on static tensile strength and fatigue cycle life of lap riveted structures. The relationship between the squeezing force, the dimension of the rivet-driving head, and the upsetting diameter of the rivet rod was obtained by the theoretical method. The material flow characteristic of the rivet and rivet holes was established by a detailed finite element model (FEM). Experiments verified the validity of the theoretical method and FEM, and the variation of static tensile failure load and fatigue cycle life under different squeezing forces was obtained by experiments. The fracture mode and microstructure of the static tensile failure specimens and fatigue cycle life specimens were characterized by scanning electron microscopy, and the fracture formation process was discussed. The results showed that the static failure load, high cycle fatigue life, and low cycle fatigue life were increased by 5.40% and 6.21%, 90.02% and 476.60%, and 19.96% and 99.15% under 20.23 and 23.24 kN squeezing forces, respectively, compared with 17.54 kN. In addition, with the increase of the squeezing force, the area of the brittle fracture region and the crack propagation zone will increase.