Study On Low Cycle Fatigue Life Damage Of Steam Turbine's High-Mid Pressure Rotor Using Finite Element Method

Steam turbine rotor will bear alternating thermal stress during its operation. After a periodic circulation, there will be fatigue crackle on the metal surface, which will gradually spread to rupture; all factors above may have an important influence on the life of Steam turbine rotor. The paper studies the low cycle fatigue life damage of steam turbine's middle-and-high stress rotor on the condition of cold start-up. It is important for the safe and economical operation of electric power generation equipment.On account of a 300MW middle-and-high stress rotor structure which comes from one Generate Electricity Litd of Xiangtan. It predigested the geometry model of steam turbine rotor through theory and experience, meanwhile ,using of Solidworks, physics model of stem trubine rotor was striked up, at the same time carried out analysis by ALGOR, a kind of finite element analysing software, which has strong gridding carving up technology and complex after-manage-function that could improve precision and efficiency of results. Moreover, through carved up grid to finite element model of rotor, this paper analyzed rotor's temperature field and stress field under different temperature as well as bringde out the impact of temperature rise rate on temperature field and stress field, and then the research showed that temperature rise rate is the main factor which impacts the thermal stress.The paper based on life evaluation method of Steam turbine rotor, crack extend theory and security theory, meanwhile considered stress calculation result as well as introduceed Continuous Mechanics of nonlinearity damnification model and then calculated low cycle fatigue life damage on the condition of complex stress, get the best cold start temperature rise rate. Compared with traditional single axes non linearity damnification model and Manson-Coffin cumulation daminfication theory model, Polyaxis Continuous damnification model Because of introducing triaxiality factor and taking consideration of the impact of life damage from Polyaxis stress, the results which Analysised by Polyaxis Continuous damnification model To some degree were more close to practical project.From study of temperature-thermal stress field numerical value stimulant of 300MW steam turbine rotor, the paper researched temperature rise rate-temperature difference, temperature difference-thermal stress, stress-damage, damage-life's relationship and it's disciplinarian, and then put forward blue print of reasonable optimization cold start-up. According to those disciplinarians, all study above provided effective evidence to safely and economical operation of machine, at the same time, it also offers references to investigation on steam turbine rotors'life damage under other situations.