Calculation of plastic notch stress intensity factor and strain energy density by Peak Stress Method under low-cycle fatigue conditions

In this article, an idea for prediction of low-cycle fatigue durability of notched components is presented. The concept implements the Peak Stress Method into the calculation of both the plastic notch stress intensity factor and averaged elasto-plastic strain energy density. The scatter reduction which is characteristic for the approach using the strain energy density calculation under high-cycle fatigue conditions is less pronounced in the low-cycle fatigue area. Importantly, the otherwise changed slope of the durability curve in the low-cycle fatigue regime of the material remains almost equal to the slope in the high-cycle fatigue regime of the material using the implemented method. The method has been validated on tension–compression testing of plain and V-notched specimens of structural steel St-52 with three notch angles: 35°, 90° and 135°. It is shown that significant agreement can be drawn between predictions using the Peak Stress Method and finite element evaluation of the averaged strain energy density.