THE LOW CYCLIC FATIGUE CRACK GROWTH PREDICTION MODEL BASED ON MATERIAL’S LOW CYCLIC FATIGUE PROPERTIES

Based on the cyclic stress-strain field of a fatigue crack tip, an average cyclic damage parameter from the strain amplitude is defined. By introducing Miner theory, this paper theoretically establishes the relationship between the material’s low cycle fatigue properties and the low cycle fatigue crack propagation behavior. And the fatigue process size is measured as the monotonic plastic zone size in the crack propagation direction. Thus, based on elasto-plastic strain fatigue cumulative damage, a new fatigue crack growth prediction model is set up, which improve the prediction models proposed in the pertinent published literatures. This new model considers the elasto-plastic strain damage contribution of the material located in the monotonic plastic zone. What is more, parameters involved in the model are determined by their physical properties without human debugging. Through the comparisons with the experimental results of Cr2Ni2MoV steel and TC4 alloy, it is clearly concluded that the new low cyclic fatigue crack growth prediction model have good accuracy.