In order to predict the bolt’s stress distribution under the pre-tightening state and the loosening process under the transverse load, a 3D model considering the bolt thread structure was established by finite element method (FEM). In this study, the looseness effect of transverse load amplitude, the friction coefficient of the bolt head load bearing surface and the thread contact surface are mainly studied. The result indicated that the stress under bolt pre-tightening is mainly concentrated on the contact part of the bolt’s head and bar. At the contact area of the load threads at one end and the transition part between the bolt bar and the thread, the stress and axial direction of the thread part are offset. Under the transverse displacement load, the sliding of the bolt can be divided into three stages: full contact, viscous contact, and full slip. The numerical model of bolt relaxation obtained in this paper can provide reference for the application, checking and prediction of threaded fasteners.

为了预测螺栓在预紧状态下的应力分布和横向载荷下的松动过程，采用有限元方法（FEM）建立了考虑螺栓螺纹结构的3D模型。在这项研究中，主要研究横向载荷幅值的松动效应，螺栓头载荷承受面和螺纹接触面的摩擦系数。结果表明，螺栓预紧时的应力主要集中在螺栓头与杆的接触部分。在负载螺纹的一端和螺栓杆与螺纹之间的过渡部分的接触区域，螺纹部分的应力和轴向方向是偏移的。在横向位移载荷下，螺栓的滑动可分为三个阶段：全接触，粘接触，和完整的滑。本文获得的螺栓松弛数值模型可以为螺纹紧固件的应用，检查和预测提供参考。