Fatigue behavior and life prediction of bolt connections based on ABAQUS software

The finite element analysis method was used to predict the behavior and fatigue life of bolted connections under fatigue loads. Firstly, a detailed finite element model of the lap fatigue structure was established based on ABAQUS software. The Johnson-Cook constitutive model was used to describe the elastic and plastic behavior of the material, in order to improve the accuracy of the simulation results. Fatigue simulation experiments were conducted on single bolt and multi bolt lap structures by loading different pretightening forces, load amplitudes, and load frequencies, and the effectiveness of the model was verified. The results show that moderately increasing the pretightening force could significantly prolong the fatigue life of bolts. High frequency fatigue loads could cause the material to undergo a large number of stress cycles in a short period of time, accelerate the accumulation of fatigue damage, and significantly shorten the fatigue life of bolts. For multi bolt lap structures, due to the uniform distribution of loads among multiple bolts, the stress concentration effect of a single bolt was reduced, the overall structural stiffness was increased, and micro motion wear was reduced, thereby extended its fatigue life. The fatigue damage of bolted connections was mainly concentrated in the middle of the screw, the thread, and the transition area between the bolt head and the rod. These high stress concentration areas were the main locations for fatigue crack initiation and propagation, ultimately led to the fracture of bolted connection structures.