双孔耳片衬套冷挤压强化的残余应力和疲劳寿命

To improve the fatigue strength and service life of the connecting hole of double-hole lug, the numerical simulation model of the double-hole lug extrusion process was established using the bushing cold extrusion strengthening technology. The variation law of values and distribution area of stress was obtained. Combined with finite element analysis and fatigue test methods, the fatigue life of the lug-bushing specimen after cold extrusion was obtained, and the macroscopic and microscopic morphologies of the fractures were analyzed. The results show that the increase of extrusion amount increases the tangential residual compressive stress. At the same time, the distribution areas of compressive stress along the thickness direction of bushing and the radial direction of lug are enlarged. The extrusion process of mandrel exacerbates the inhomogeneity of the stress distribution along the thickness direction. Larger compressive stress area appears at the position 2-8 mm away from the extrusion surface. Comprehensively considering the influence of extrusion amount on the average value and distribution area of residual compressive stress, the optimal extrusion amount is determined to be 4%, and appropriate increase of the extrusion amount can effectively improve the fatigue life of the components. When the extrusion amount is 1. 5%, the fatigue life obtained from the fatigue test is 316957 cycles and the simulation value of fatigue life is 338844 cycles, presenting a small relative error. The fracture positions of the lug-bushing components all occurr at the minimum cross-section of the hole, the fracture direction of the crack is basically perpendicular to the principal stress direction, and many crack strips with different sizes occur.