水轮机顶盖螺栓疲劳强度的影响因素研究

Study on Influencing Factors of Fatigue Strength of Head Cover Bolts of Hydraulic Turbine

螺栓应力幅是决定螺栓疲劳强度的直接因素,螺栓应力幅越小,螺栓的疲劳强度越大。为了研究螺栓应力幅的影响因素,通过有限元方法对某顶盖及螺栓进行了整体建模和结构受力分析,提取了不同螺栓和法兰组合形式下螺栓的应力幅。结果表明,单法兰型式螺栓疲劳强度优于双法兰型式,下法兰型式螺栓疲劳强度优于上、中法兰型式;加厚双法兰结构法兰上板、下板、筋板厚度及上下板间距均可提高螺栓疲劳强度;增大螺栓头支撑直径和螺栓与法兰的接触面积,可提高螺栓的疲劳强度。

The stress amplitude of bolt is the direct factor to determine the fatigue strength of bolt.The smaller the stress amplitude of bolt is,the greater the fatigue strength of bolt is.In order to study the influencing factors of the stress amplitude of bolt,this paper carries out the overall modeling and structural stress analysis of a certain head cover and bolt by finite element method,and extracts the stress amplitude of bolts under different bolt and flange combinations.The results show that the fatigue strength of single flange bolt is better than that of double flange bolt,and that of lower flange bolt is better than that of upper and middle flange bolt;The fatigue strength of double flange bolt can be improved by thickening the thickness of upper plate,lower plate,rib plate and spacing between upper and lower plates as well as increasing the support diameter of bolt head and the contact area between bolt and flange.