A prediction method for fatigue crack growth under high stress levels using accumulative plastic damage properties

Abstract

The objective of this research is to elucidate the characteristics of low-cycle fatigue crack propagation from the perspective of accumulative plastic damage, proposing a reliable prediction model for assessing the crack growth in EH-36 steel subjected to high stress levels. The plastic damage of the crack-tip is measured by the plastic energy at the critical distance point from the crack-tip. And, a prediction program is developed to calculate the fatigue damage accumulation and fatigue crack growth rates. In order to verify the validity of the prediction method, a sequence of quantitative loading experiments is conducted on specimens consisting of cracked plates and stiffened plates (made of EH-36 steel). The findings show that the prediction model effectively represents the fatigue crack growth behavior in high stress conditions. Increasing the mean stress and stress amplitude is beneficial to increase plastic energy increments, thereby accelerating the progression of fatigue damage towards the critical threshold.