Influence of the accumulated error in thread pitch on the stress–strain state and cyclic strength of threaded joints

Using the finite element method, the analysis of influence of errors in pitch during the thread production on the behavior of stress distribution in stud–nut joints is performed. The value of maximum local stresses in studs of a threaded joint is shown to substantially depend on errors in thread pitch of a stud and a nut. On the basis of the analyses of stresses and strains under cyclic loading, fatigue curves are plotted for the threaded joints having deviations in thread pitch. It is shown that, with a rational selection of the deviation in pitch, the cyclic strength of threaded joints can be considerably increased. The results of analysis agree satisfactorily with the data of fatigue tests of the M39 × 3 threaded joints.