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• Point-wise stress criterion was coupled to the energy release rate criterion. • The proposed criterion gives identical predictions with Carpinteri's criterion. • Carpinteri's criterion gives a lower prediction than Leguillon's criterion due to the higher stress employed. • Carpinteri's criterion is more accurate than Leguillon's criterion. In the framework of finite fracture mechanics, two coupled criteria were proposed by Leguillon and Carpinteri, respectively. Leguillon's criterion uses the point-wise stress criterion, whereas Carpinteri's criterion uses the averaged stress criterion. Both criteria employ the same incremental energy release rate criterion which can be considered as an averaged energy criterion. Mathematically, the averaged energy criterion can be transformed into an equivalent point-wise criterion. In this paper, a new coupled criterion based on the point-wise stress and energy criteria was proposed. The proposed criterion is equivalent to Carpinteri's criterion when predicting notch fatigue limits. All the three forms of coupled criteria were checked and compared by a large number of experimental results including V-shaped and central hole specimens. When performing the coupled criteria, power functions derived from finite element analysis were used to express the energy release rate and notch stress distributions. The effect of notch size on the crack extension lengths were investigated. [ABSTRACT FROM AUTHOR]

• Failure criterion of FFM expressed by effective stress similar with line method. • Power functions deriving from FEA results proposed to describe stress and SIF distribution. • Critical distance of coupled method within range of 1.589 a 0 to 2 a 0 as notch size varies. • LM is an approximation of LM-FFM and gives reasonable predictions. The energy based failure criterion Finite Fracture Mechanics is transformed into a stress based failure criterion and expressed by an effective stress similar with Line Method. After coupling the two criterions, the theoretical critical distance expression is derived based on notch stress distribution, stress intensity factor function and material characteristic length. The effect of notch size and material characteristic length on the critical distance and fatigue limit prediction was analyzed for a group of V-shaped notches. Then, the coupled method was validated by a large number of experimental results. It is revealed that the Line Method and coupled method are the same except that they employ different critical distances. The validity of Line Method was discussed based on the difference of critical distances and fatigue limit predictions between the Line Method and coupled method. [ABSTRACT FROM AUTHOR]