Prediction of the fatigue life of notched specimens: The influence of the surface quality produced by machining

Abstract

The article introduces a method for fatigue lifetime predictions of notched specimens. The method uses fracture stresses of smooth and notched specimens with notch radius r=0.2 mm. These two sets of experimental data are evaluated with the knowledge of axial stress distributions of the notched specimens using average stress over a length parameter l. This parameter l is considered to be a material characteristic (depending on the number of cycles to failure) and can be used for lifetime predictions of notched specimens with various notch radii. The predictions are compared to experimental data and analyzed. There is a strong influence of the process of machining of notches, which can lead to fatigue failure earlier than predicted. The data are evaluated in the area of high cycle fatigue and gigacycle fatigue.The article introduces a method for fatigue lifetime predictions of notched specimens. The method uses fracture stresses of smooth and notched specimens with notch radius r=0.2 mm. These two sets of experimental data are evaluated with the knowledge of axial stress distributions of the notched specimens using average stress over a length parameter l. This parameter l is considered to be a material characteristic (depending on the number of cycles to failure) and can be used for lifetime predictions of notched specimens with various notch radii. The predictions are compared to experimental data and analyzed. There is a strong influence of the process of machining of notches, which can lead to fatigue failure earlier than predicted. The data are evaluated in the area of high cycle fatigue and gigacycle fatigue.