Short or Stage I crack growth represents a unique case where the Paris-Erdogan Linear Elastic Fracture Mechanics model fails to predict crack growth and hence fatigue life. The propagation rate of short cracks has been found in numerous works and for a variety of materials to be significantly higher than that predicted by the aforementioned model [
]. Yet, there is a strong relation between the material and the extent of short cracking. In general, aluminium alloys exhibit a much larger short cracking potential to high strength steels. In addition, stress ratio has also been found to play an important role on such phenomenon [
]. In brief, the extent of short cracking has been found to decrease with the stress ratio and even disappearing after a particular value [
]. In a number of papers Rodopoulos and co-workers argued that the phenomenon depends on the ratio between the fatigue limit and the cyclic yield stress [
], as shown in Figure.1.