采用有限元法建立了基于某电厂汽轮机转子温度场和热应力场的数学模型。在对汽轮机的冷态启动、温态启动、热态启动以及滑参数停机4个工况下的瞬态温度场以及热应力场进行模拟分析基础上，确定转子最大热应力点作为监测点，对监测部位的温度与热应力进行了疲劳损耗仿真计算。根据最小二乘法获得转子钢材料的疲劳特性曲线，利用MATLAB进行多项式拟合，获得转子应变与疲劳寿命损耗的函数关系式，求得汽轮机转子启停下的低周疲劳寿命。研究结果表明：该机组累积十年运行条件下形成的疲劳损耗为2.506%。机组冷态启动过程中，转子承受最大温差与热应力，最大热应力值445 MPa；当温升率由3 ℃/min提高到4 ℃/min时，转子的低周疲劳寿命损耗由0.040%上升到0.103%，寿命损耗明显增大。

Finite element method is used to establish a mathematical model of temperature field and thermal stress field for a turbine rotor.ANSYS software is used to simulate different processes,including cold start,warm start,hot start and sliding parameter downtime.The instantaneous thermal load in terms of temperature field and thermal stress field is analyzed to determine the biggest stress points for the monitoring sites.Then the temperature and thermal stress at the monitoring sites are used to calculate the fatigue wear.Based on the least square method,the rotor fatigue characteristic curve of steel material is obtained.With the polynomial fitting in MATLAB,the correlation between the strain and the fatigue life loss of the rotor is generated,and the low cycle fatigue life for the steam turbine rotor is determined for the process of revstop.The results show that the unit being operating for ten years has accumulated fatigue loss of 2.506%.The maximum temperature and thermal stress appear in the process of cold start,with the maximum thermal stress at 445 MPa.With the temperature rise at a rate of 3 ℃/min,the low cycle fatigue life of rotor loss is 0.040%.With the temperature rise rate of 4 ℃/min,the low cycle fatigue life loss is 0.103%.

TK474.7+2