COMBINED HIGH AND LOW CYCLE FATIGUE LIFE PREDICTION MODEL TAKING ACCOUNT OF COUPLED DAMAGE

Mechanical parts such as gas turbine blades are often subjected to low cycle fatigue caused by low⁃frequency centrifugal force and high cycle fatigue caused by high⁃frequency vibration loads during the working process,and the damage caused by the combined cycle loadings is one of the important factors for fatigue.The damage generated under the combined high and low cycle loading is not a simple damage superposition,and the coupled damage due to the interaction of high and low cycle loading also needs to be considered.On the basis of Miner′s rule,through considering the coupled damage caused by the interaction between high and low cycle loading,combined high and low cycle fatigue life prediction model was established.The proposed model was compared with the Miner model and the Trufyakov⁃Kovalchuk model through the material test data.The results show that the proposed model has a good prediction accuracy.