Abstract: Bolted connection is an important connection mode of battery pack, and due to the influence of vibration, it may be loose, and its connection reliability affects the performance and safety of battery system. This paper mainly adopts the simulation and test methods to study the torque attenuation of bolt connection between the upper and lower boxes of battery pack, calculates the modal shape of battery pack through simulation, and analyzes the bolt force distribution. According to the requirements of battery system vibration resistance in battery pack and system safety requirements and test methods (GB 31467.3－2015), the whole random vibration test of battery pack is carried out to compare the relative torque attenuation values and distribution rules of bolts in upper and lower case of battery pack before vibration, 1 h vibration and 3 h vibration.The results show that the bolt torque attenuation is about 6% after 1 h random vibration, and about 17% after 3 h vibration, and moreover, the structural characteristics of the battery pack affect the bolt torque attenuation distribution. In the region with fixed lug, the bolt torque attenuation is small, while in the region without fixed lug, the bolt torque attenuation is large, which provides reference for the reliability of bolt connection of battery system.

Key words: Box fastener; Torque attenuation characteristics; Vehicle power battery; Random vibration text

摘要： 螺栓连接是电池包的一种重要连接方式，由于振动影响可能会产生松动，其连接可靠 性影响电池系统的性能和安全。文章主要采用模拟仿真和试验测试方式，研究电池包上下箱 体之间的螺栓连接扭矩衰减情况，通过仿真计算电池包的模态振型，并分析螺栓受力分布， 参照《电池包及系统安全要求及试验方法》（GB 31467.3－2015）中对电池系统耐振动性的要 求，开展电池包整体随机振动试验，对比振动前、振动 1 h 和振动 3 h 后，电池包上下箱体螺 栓的扭矩衰减相对值及其分布规律。研究结果显示，随机振动 1 h 后，螺栓扭矩衰减 6%左右， 振动 3 h 后，螺栓扭矩衰减均值衰减 17%左右，且电池包结构特点影响螺栓扭矩衰减分布，在 有固定吊耳的位置区域，扭矩衰减较小，而在缺乏固定吊耳的区域，螺栓扭矩衰减较大，其 为电池系统螺栓连接可靠性提供参考依据。

关键词: 箱体紧固件；扭矩衰减特性；车用动力电池；随机振动试验