Effect of the nut position changings on the fatigue life of the stud-nut connection under cyclic axial loading

Abstract

The effect of the nut position changings to the fatigue life prolongation of the threaded connection is examined. The applied preload and the load amplitude together with the stress concentration define the damage accumulation rate distribution along the stud thread. Due to the nut position periodical changings not one but the several risky points of the stud thread during a certain loading period experience the damage accumulation with the maximum rate. During the other loading periods they are remote from the bearing surface of the nut and lies in the segments of the connection with the lower loading levels. The mathematical model based on the Miner's linear cumulative damage rule express a coherence of the damage accumulations in the risky points of the stud and allows estimating the prolongation of the fatigue life.