螺栓啮合螺纹段的轴力、等效应力分布及摩擦的影响分析

采用有限元数值模拟方法，考虑螺栓材料的弹塑性性质，计算分析普通三角形螺纹螺栓-螺母副在轴向力作用下的内力、应力和变形规律。给出不同总轴力下螺栓螺纹段中轴向力和螺牙根部最大等效应力沿轴向的非线性分布规律和总轴力在各圈螺纹上的分配关系；对由轴对称二维螺牙模型、三维回转螺牙模型和三维螺旋线型螺牙模型计算得到的对应各圈螺纹上的轴向力和螺牙根部最大等效应力进行比较，指出在工程分析中，对于轴向载荷作用情况，可近似将螺旋线型螺牙简化为三维回转螺牙；给出螺栓绕轴线的转角和各圈螺纹上传递的轴向力随螺牙界面摩擦因数的非线性变化规律，得出轴向外力下螺纹段最大等效应力随摩擦因数增大而减小的规律。

ANALYSIS OF DISTRIBUTIONS OF AND FRICTIONAL EFFECT ON AXIAL FORCE AND EQUIVALENT STRESS IN A THREADED BOLT

By using finite element method and taking bolt material elastic-plasticity into consideration, the distribution laws of inner force and stresses in and deformation of a general triangle screwed bolt under the action of axial force were numerically calculated and analyzed. The nonlinear distribution laws of axial force along the bolt axis and the maximum equivalent stress at the roots of the threads and the allocation of total axial force acted on each circle of the screws were obtained. By comparing the results of axial force on each circle of the screws and the maximum equivalent stress at the roots of the threads calculated from three different numerical models that are axisymmetric 2D model, 3D revolving one and 3D spiral one, the conclusion is reached that in engineering, the 3D revolving model can be used to simulate approximately the general triangle threaded bolt subjected to axial force. Moreover, the nonlinear changes of the rotating angle of the bolt around its axis and the axial force distributed on each circle of the screws with interfacial friction factor of the screws are shown, and among them, the maximum equivalent stress in the threaded portion decreases with increase of the friction factor.