中文摘要：

采用ANSYS有限元数值模拟的方法建立传动螺纹副阶梯式螺母模型，利用APDL参数化语言将不同螺母公差配合尺寸组合进行模拟，结果显示阶梯式螺母中上端螺牙应力水平和螺牙接触面接触压应力水平均有所提高，同时发现单个螺牙接触面上压应力分布不均，并且分布规律也不一样，还发现螺母螺牙牙根处的应力在轴向方向呈现波浪递增的形式变化，最后利用螺母螺牙轴向应力的平均值和标准差找到最优公差配合组合，使螺母螺牙载荷均匀化水平进一步提高。

英文摘要：

The finite-element numerical simulation method was applied to establish the model of stepped construction of transmission screw nut, and different types of tolerance and fit of the transmission screw nut were simulated by using parameter language of APDL. The results show that the stress of upper screw tooth and the contact pressure of upper screw tooth surface on the stepped construction of transmission screw nut are increased. The contact surface pressure distribution of single screw tooth is uneven, and the distributed regularity of every screw tooth is different too. It is also found that the stress of screw nut root in the axial direction is presented a change of waving increasing, and based on the average value and standard deviation of axial stresses along the screw nut root, the optimal combination of tolerance and fit is found, which can further improve the load equalization levels of screw nut tooth.