Experimental and calculation challenges of crack propagation in notches - From initiation to end of lifetime

Year: 
2017
Month: 
6
Day: 
17
Pages: 
395-404
DOI: 
10.1016/j.ijfatigue.2017.06.016
Type: 
Journal Articles
Journal: 
International Journal of Fatigue
Volume: 
103
Abstract: 

Notches reduce significantly the lifetime of cyclically loaded components due to their stress concentration and early crack initiation. In this work the initiation and crack growth behaviour of cracks in notches has been studied with the direct current potential drop technique. Due to the notch geometry and semielliptical shape of the starting crack, significant differences between the crack length determination by the Johnson equation and the real crack length have been observed. By means of numerical simulations for single and multiple crack initiation sites, a calibration function for determining the crack length from the potential drop has been developed. The calibration function results in a good agreement between the estimated and measured changes of the potential drop and permits a quite accurate estimation of the crack initiation life time.