Finite Element Simulation Of The Creep-fatigue Behavior Of A GH4169 Gas Turbine Disk And Its Life Prediction

At present,GH4169 alloys are widely used in the manufacture of low pressure blades for many aeroengines and large turbines.Aero-engine is a complex integrated system consisting of various components.The working environment of components is very complex.When the engine is in working condition,it is subjected to high temperature,corrosion,etc.,and it also bears a variety of complicated loads and damages,especially the creep fatigue interaction of aeroengine turbine disk in high temperature environment is puts forward new challenges to the research of traditional life and reliability technology.In order to solve the above problems,based on the finite element analysis method of creep damage user subroutines,the creep-fatigue cyclic deformation behavior of GH4169 alloy is systematically studied,and the finite element analysis and life prediction of aero turbine disk based on the non-uniform cyclic constitutive model are carried out.The main research work and conclusions are as follows:(1)The Chaboche plastic constitutive model coupled by The nonlinear kinematic hardening rule and isotropic hardening rule and Strain-Hardening creep constitutive model are used to describe the mechanical properties of the GH4169 alloy.The uniaxial tension and low cycle fatigue test simulations are used to determine the mechanical properties of the GH4169 alloy.The material performance parameters in the constitutive model are determined.(2)Based on the cyclic constitutive model of combined The nonlinear kinematic hardening rule and isotropic hardening rule,the creep-fatigue cyclic deformation behavior of GH4169 material is simulated accurately by combining the Strain-Hardening creep constitutive model and the advanced creep fatigue damage model.The finite element analysis shows that:with the increase of holding time,the compressive stress increases and the stress relaxation effect becomes more obvious.The creep damage of each cycle is mainly related to the holding time.The longer the holding time is,the higher the creep damage per cycle is,and the fatigue damage occupies the leading position in the total damage per cycle.The creep-fatigue life of GH4169 alloy decreases significantly with the increase of the strain amplitude.In addition,with the increasing of the holding time,the life of the specimen is gradually reduced.(3)In consideration of the rotational speed,the ABAQUS finite element software was used to analyze the elasto-plastic finite element stress and strain of turbine disk by applying cyclic load to aero turbine structure.The cyclic constitutive model and the creep fatigue damage subroutine are used to predict the creep fatigue life of the turbine disk.The stress and strain analysis of finite element shows that:the dangerous part of turbine disk is the central hole of the turbine disk,and the maximum equivalent stress and maximum principal strain appear at the center hole of the turbine disk under different speeds.Fatigue load is the main factor affecting the creep fatigue life.When the total cumulative damage reaches 1,the cumulative fatigue damage plays a leading role in the total cumulative damage.The creep fatigue life of the turbine disk is related to the speed of the turbine disk.The higher the speed is,the faster the cumulative damage of the turbine disk reaches 1,the shorter the creep fatigue life of the turbine disk.The speed also affects the proportion of fatigue cumulative damage and creep cumulative damage in the total cumulative damage.The higher the rotational speed,the smaller the percentage of cumulative damage to the total cumulative damage,and the lower the rotational speed,the larger the proportion of creep cumulative damage to the total cumulative damage.