【作者】 刘丽君；

【导师】 雷宏刚；

【作者基本信息】 太原理工大学 ， 结构工程， 2003， 硕士

【摘要】 螺栓球节点网架的疲劳主要是节点的疲劳，而节点的疲劳关键是高强螺栓的疲劳。 本文从材料、构造加工、制作安装及工作应力等四个方面系统地分析了高强螺栓的疲劳影响因素及影响程度。 应力集中是高强螺栓发生疲劳断裂最主要的原因。本文以ANSYS有限元软件为研究手段，针对网架螺栓球节点的8种螺栓规格进行单缺口应力集中分析，定量求得相应的应力集中系数K_t；论述了螺纹升角φ、螺纹牙根圆角半径R及球栓直径比D/d对K_t的影响，并引入相应的影响系数α₁、α₂及α₃，最终提出了应力集中系数K的计算公式。在K研究工作的基础上，求得相应的疲劳缺口系数K_f，进而推定高强螺栓的疲劳极限应力幅及其允许应力幅。 最后，将本文的理论研究成果与常幅疲劳试验数据相结合，并引入“热点应力幅”的概念，建立了螺栓球节点网架结构的疲劳验算方法。更多还原

【Abstract】 Fatigue of grid structure with bolt-sphere joints mainly behaves fatigue in joints, the critical of which is fatigue of high strength bolt.Lots of fatigue influencing factors on high strength bolts is analyzed in this paper systematically, including materials, construction processing, fixing and working stress.The most important reason for fatigue fracture of high strength bolts is stress concentration. Based on ANSYS, this paper studies stress concentration on single notch of eight kinds of high strength bolts used in grid structure, obtaining their stress concentration coefficients, discussing the effect of ascending angle, bottom radius of screw thread and bolt-ball on stress concentration, introducing their effect coefficients of a1,a2,a3, putting forward the formulae of stress concentration coefficient. Based on stress concentration coefficient, fatigue notch coefficient, fatigue limit and range of allowed stress are obtained.Finally, theoretical results and the fatigue test data of equalamplitude are combined, which is introduced the conception of"range of hotspot stress" , and the method of fatigue designfor grid structure with bolt-sphere joints is obtained in this paper.更多还原