Nonlinear Finite Element Analysis of Equivalent Iwan Model Considering Threaded Connections

Abstract Aiming at the complex geometric nonlinearity of the threaded connection and its contact behavior, a finite element model equivalent to the Iwan model is constructed for nonlinear analysis of the threaded connection. Firstly, the subroutine of the equivalent Iwan model is constructed to simulate the nonlinear contact behavior of the threaded connection; then, the finite element model of the threaded connection is constructed in Abaqus software to simulate the relationship between the torque and the preload force of the threads during tightening, and the accuracy and nonlinearity are verified with the theoretical model; finally, the influences of the coefficient of friction and the rotational amplitude on the mechanical response of the threaded connection are explored. The results show that the finite element model based on the Iwan model can accurately capture the contact behavior of the threaded joint; the increase of the friction coefficient will increase the friction between the contact surfaces, which will increase the preload force, but it may also increase the stress concentration and the risk of deformation; the increase of the rotational amplitude can increase the preload force, but it may also lead to the stress concentration and increase the risk of plastic deformation of the structure.