典型连接结构螺栓的附加弯矩形成机理与承载能力研究及结构优化设计

针对典型连接结构中, 高强螺栓在受拉工况下因产生附加弯矩而极大削弱其承载能力的问题, 开展了螺栓附加弯矩产生的机理研究, 并提出了一种有效降低螺栓附加弯矩的结构优化设计方法. 首先, 建立典型连接结构的等效力学模型, 推导出螺栓附加弯矩的解析解, 进一步开展数值仿真分析, 验证了解析方法的正确性. 考虑螺栓同时承受拉弯耦合载荷工况, 引入梁塑性弯曲理论, 研究了不同拉弯组合下的螺栓截面各类应力分布的交互关系, 并给出了考虑轴力影响的弯矩塑性折减系数. 基于最大应力破坏准则, 开展了考虑附加弯矩和弯曲塑性影响的螺栓载荷失效判据研究, 该判据更加具有工程应用价值. 从机理出发, 开展典型连接结构优化设计以降低螺栓的附加弯矩进而提高其承载能力, 进一步采用解析方法, 阐述了铰支球头的工作机理. 采用数值仿真方法, 开展了螺栓附加弯矩灵敏度分析, 验证了优化设计方法的有效性. 进一步开展试验研究, 获得不同连接状态下螺栓的附加弯矩, 验证了优化设计方法的正确性和可行性. 该方法能够极大降低高强螺栓的附加弯矩, 最大程度发挥螺栓的承载能力, 提高连接结构的可靠性. 

RESEARCH ON THE FORMATION MECHANISM OF ADDITIONAL BENDING MOMENT AND BEARING CAPACITY OF BOLT OF TYPICAL CONNECTED STRUCTURE AND STRUCTURAL OPTIMIZATION DESIGN

Considering the problem that the bearing capacity of the high-strength bolt is greatly weakened by the additional bending moment in the tensile condition of the typical connection structure, a mechanism study on the generation of additional bending moment of the bolt is carried out, and a structural optimization design method is proposed to effectively reduce the additional bending moment of the bolt. The analytical solution of the additional bending moment of the bolt is derived based on the established equivalent mechanical model of the typical connection structure. The correctness of the analytical solution is verified by numerical simulation. Considering that the bolt is subjected to tensile and bending coupled loads at the same time, the interaction of various stress distributions on the bolt across-section under different tensile and bending combinations is studied by introducing the plastic bending theory of the beam, and the plastic reduction coefficient of bending moment considering the influence of axial force is given. Based on the maximum stress failure criterion, a study on the failure criterion of bolts considering additional bending moment and bending plasticity is carried out, which has more engineering application value. Based on the mechanism, the optimization design of typical connection structure is carried out to reduce the additional bending moment of the bolt and thus improve bolt’s bearing capacity. The working mechanism of the hinged ball joint is expounded by analytical method. The sensitivity analysis of the additional bending moment of the bolt is carried out based on numerical simulation, which verifies the effectiveness of the optimization design method. The test research is then carried out and the additional bending moment of the bolt in different connection status are obtained. The test results verify the correctness and feasibility of the optimization design method. This method is capable of greatly reducing the additional bending moment of the high-strength bolt, maximizing the bearing capacity of the bolt, and improving the reliability of the connection structure.