Nonlinear finite element analysis for axial load distribution of thread considering plastic deformation

Due to the localized high stress transmission and plastic deformation uncertainties, certain threads at the root of fasteners may experience extremely high stress in threaded connections, potentially leading to structural strength failure and premature fatigue. This study proposes an analysis method for stress distribution considering plastic deformation based on an analytical model of thread axial force distribution within the elastic range. A refined finite element model considering the helix angle of threads was established, and a stress distribution analysis of thread teeth was completed. The accuracy of the finite element model was verified through comparison with theoretical calculations. Additionally, to study the influence of different factors on the axial stress distribution of threads, a finite element model of standard threaded connections was established, in which parameters such as preload level, number of engaged threads, and root radius were taken into account.