摘要
水轮机顶盖联接螺栓在运行过程中长期承受交变荷载,由此导致的疲劳损伤造成了多次重大事故,因而有必要对其疲劳寿命计算方法进行深入研究,以提高顶盖联接螺栓疲劳寿命计算的准确性。针对以上问题,提出了一种基于功率密度与短时傅里叶分析(PD-STFA)相结合的水轮机顶盖联接螺栓疲劳寿命计算方法,重点研究加载频率和变幅荷载的耦合作用对顶盖联接螺栓疲劳寿命影响。首先采用有限元法计算出联接螺栓的危险截面位置和应力;其次采用基于应变的中空压力传感器测得螺栓头部接触面平均应力,并根据广义胡克定律将实测得到的螺栓头部接触面平均应力转换为危险截面的受力;最后基于线性损伤累积理论,采用基于PD-STFA方法与传统雨流计数法分别计算顶盖联接螺栓疲劳寿命。计算结果表明,基于PD-STFA方法计算顶盖联接螺栓疲劳寿命为1.966×105h,传统雨流计数法为4.113×105h。根据对电站用户调研,基于PD-STFA方法计算结果更接近螺栓实际工作寿命30 a左右,能够更准确地预测水轮机顶盖联接螺栓的疲劳寿命,为水轮机安全稳定运行提供理论保障。
Long-term alternating loads on the connecting bolts of hydro-turbine head cover,which results in fatigue damage causing many serious accidents.Therefore,it is necessary to carry out in-depth study on the calculation method of fatigue life of head cover bolts in order to improve the accuracy of fatigue life calculation.In order to solve the above problems,a method for calculating the fatigue life of Turbine head cover bolts based on combination of power density and short-time Fourier analysis(PD-STFA) is put forward,with emphasis on the influence of coupling action of loading frequency and amplitude load on the fatigue life of head cover bolts.Firstly,the position and stress of dangerous section of connecting bolt are calculated by finite element method;secondly,the average stress of contact surface of bolt head is measured by strain-based hollow pressure sensor,and then the measured average stress of contact surface of bolt head is transformed into the stress of dangerous section according to generalized Hooke’s law;finally,based on linear damage accumulation theory,the fatigue life of the head cover bolts is calculated by PD-STFA method and the traditional rain flow counting method.The calculation results show that the fatigue life of the head cover bolts is 1.966× 10~5 h based on PD-STFA method and 4.113 ×10~5 h based on traditional rain flow counting method.According to the investigation of power plant users,the calculation results based on PD-STFA method are closer to the actual service life of bolts for about 30 years,and can predict the fatigue life of the turbine head cover connecting bolts more accurately,thus providing theoretical guarantee for the safe and stable operation of the hydro-turbine.
作者
刘育
晋健
王勇飞
赵俊杰
余波
LIU Yu;JIN Jian;WANG YongFei;ZHAO JunJie;YU Bo(China Energy Dadu River Hydropouwer Development Co.,Lad.,Chengdu 610041,China;Chengdu Dahui Zhilian Technology Co.,Lad.,Chengdu 610041,China;School of Water Resources and Hydropouer,Sichuan University,Chengdu 610065,China;Key Laboratory of Fluid and Pouer Machinery,Ministry of Education,Xihua University,Chengdu 610039,China)
出处
《机械强度》
CAS
CSCD
北大核心
2020年第6期1459-1465,共7页
Journal of Mechanical Strength
基金
国家自然科学基金项目(51709191)
四川省重大科技专项项目(2018GZDX0043)
国家能源集团科技创新项目(GJNY-18-09)资助。
关键词
顶盖螺栓
短时傅里叶分析
功率密度
雨流计数法
疲劳寿命
Head cover bolt
Short-time fourier analysis
Power density
Rain-flow counting method
Fatigue life
