高强度螺栓疲劳缺口系数的有限元分析

螺栓球节点网架结构在悬挂吊车作用下的疲劳是工程界和学术界关注的热点,该结构的疲劳关键是高强度螺栓的疲劳。该文借助ANSYS有限元软件;选取常用的M14、M20、M24、M30、M33、M39、M52、M60共8种规格40Cr制高强度螺栓为分析对象;采用20节点的SOLID95单元类型进行三维实体建模;在重点定量探讨螺栓直径、螺纹升角、螺纹牙根圆角半径及螺栓球四个主要影响因素的基础上,建立了适用于各种规格高强度螺栓疲劳缺口系数的通用计算公式,数值区间为4.35―4.89。该文的研究结论揭示了应力集中和疲劳源的关系,为进一步以热点应力或热点应力幅为参量建立螺栓球节点网架结构疲劳计算方法奠定了理论基础。

FEA ANALYSIS OF FATIGUE NOTCH COEFFICIENTS FOR HIGH-STRENGTH BOLTS

The fatigue of the grid structure with bolt-sphere joints under the function of suspended crane has been greatly concerned by engineers and researchers. The fatigue mainly behaves the fatigue of high strength bolts. ANSYS FEA is provided for studying eight kinds of 40Cr high strength bolts of M14, M20, M24, M30, M33, M39, M52 and M60. According to the quantitative analysis of four principle influencing factors of bolt diameters, screw threads, rounded corner radius of screw thread bottoms and bolt-spheres, a three-dimensional real model is developed by SOLID95 of twenty joints. A calculating formula of fatigue notch coefficients (suitable for all kinds of high strength bolts) has been given. Its data are between 4.35 and 4.89. The results point out that the relation between the stress concentration and fatigue original, which will lay a foundation for fatigue-computational methods of the grid structure with bolt-sphere joints pertinent to hot stresses and the range of hot stresses.