Failure Mechanism and Prevention Strategy of Industrial Bolt-Nut Connections
本文系统探讨了工业螺栓螺母连接的失效机理与防治策略，核心内容分为三部分：This paper systematically discusses the failure mechanism and prevention strategy of industrial bolt-nut connections, with the core content divided into three parts:
一、失效影响与分类
I. Failure Impact and Classification
1. 事故案例
1. Accident Cases
列举塔科马大桥坍塌（1940）、普莱森特桥事故（46 人死亡）等 8 起重大事故，揭示螺栓失效可能导致灾难性后果。Eight major accidents are cited, including the collapse of the Tacoma Narrows Bridge (1940) and the Pleasant Bridge accident (46 fatalities), revealing that bolt failure can lead to catastrophic consequences.
2. 失效因素分类
2. Classification of Failure Factors
可控因素：预紧力不当（占 90% 失效）、扭矩施加误差、防松措施缺失；
Controllable factors: inappropriate preload (accounting for 90% of failures), torque application errors, lack of anti-loosening measures;
Fishbone diagram analysis reveals more than 20 influencing factors (friction coefficient, temperature, assembly process, etc.);
推荐扭矩 – 转角法、超声波测量等 7 种高精度控制技术。
Seven high-precision control technologies are recommended, including the torque-angle method and ultrasonic measurement.
2. 防松技术
2. Anti-Loosening Technology
阶梯锁紧螺栓（抗横向载荷）、双螺纹干涉设计（机械自锁）、化学锁固胶（航空航天首选）；
Step-locking bolts (resistance to transverse loads), double-thread interference design (mechanical self-locking), chemical thread locking adhesives (preferred in aerospace);
对比显示结构锁紧型防松效果优于传统弹性垫圈。
Comparisons show that structural locking anti-loosening is superior to traditional elastic washers.
3. 疲劳延寿策略
3. Fatigue Life Extension Strategies
优化螺纹根部圆角（降应力集中 20%）、喷丸强化（提升 DFR 强度 80%）；
Optimizing thread root fillets (reducing stress concentration by 20%) and shot peening (increasing DFR strength by 80%);
滚压螺纹比切削螺纹寿命高 3–5 倍。
Roll-formed threads have a 3–5 times longer life than machined threads.
4. 腐蚀防护
4. Corrosion Protection
涂层工艺（锌片涂层抗点蚀）、电偶腐蚀隔离（绝缘垫片）；
Coating processes (zinc flake coating against pitting) and galvanic corrosion isolation (insulating gaskets);
SCC（应力腐蚀开裂）需监控环境介质与残余应力。
For SCC (Stress Corrosion Cracking), environmental media and residual stress must be monitored.
三、工业实践建议
III. Industrial Practice Recommendations
设计阶段：采用螺距差设计均衡载荷，法兰连接需交叉顺序分步拧紧；
Design stage: Use pitch-difference design to balance loads, and perform step-by-step cross-tightening for flange connections;
维护阶段：定期超声波检测预紧力损失，高温工况建议焊接双螺母；
Maintenance stage: Regular ultrasonic inspection for preload loss; welded double nuts are recommended for high-temperature conditions;
材料选择：避免异种金属直接接触，优先选用滚压成型 + 喷丸强化螺栓。
Material selection: Avoid direct contact between dissimilar metals; prefer roll-formed + shot-peened bolts.
结论
Conclusion
螺栓连接失效是多重因素耦合结果，需通过 “精准装配 + 主动防护 + 智能监测” 三位一体策略提升可靠性，尤其需关注腐蚀 – 疲劳协同效应。Bolt connection failure results from the coupling of multiple factors. Reliability should be improved through the three-in-one strategy of “precision assembly + active protection + intelligent monitoring”, with particular attention to the corrosion-fatigue synergistic effect.
