In this study, F_a–N curves and σ_{n_s}–N curves of bolted connections under different geometric and load parameters were obtained through tensile-shear fatigue tests. The correlation of these curves was poor and did not satisfy engineering requirements. To this end, first, an equivalent structural stress calculation model capable of accurately characterizing the stress state of a bolted connection was derived by considering the bolt load as the input condition. Subsequently, a plate-shell finite element model for bolted connections was established, and the load parameters for bolts were extracted by simulation and inputted into the equivalent structural stress calculation model to obtain the equivalent structural stress at the crack initiation position of a bolted connection. Finally, the normalized S_s–N curve of the bolted connections was fitted considering geometric and load parameters, and a fatigue evaluation method based on equivalent structural stress was designed for bolted connections. This evaluation method can act as a reference for checking the design of bolted connections and predicting their fatigue life.

在本研究中，F _a – N曲线和σ _{n_s} – N通过拉伸-剪切疲劳试验得到不同几何参数和载荷参数下螺栓连接的曲线。这些曲线的相关性较差，不满足工程要求。为此，首先以螺栓载荷为输入条件，推导出能够准确表征螺栓连接受力状态的等效结构应力计算模型。随后，建立螺栓连接板壳有限元模型，通过仿真提取螺栓载荷参数，输入等效结构应力计算模型，得到螺栓连接裂纹萌生位置的等效结构应力。最后，归一化的S _s – N结合几何参数和载荷参数对螺栓连接曲线进行拟合，设计了一种基于等效结构应力的螺栓连接疲劳评估方法。该评价方法可作为螺栓连接设计校核和疲劳寿命预测的参考。