Strain-concentration factor of circumferentially notched cylindrical bars under static tension

A new definition of the strain-concentration factor (SCNF) has been propose d for circumferentially notched cylindrical bars under static tension. The average axial strain used in the definition of this new SNCF takes into con sideration the triaxial state of stress at the net section. This is very di fferent from the definition of the conventional average axial strain, which has been defined under uniaxial state of stress. This new average axial st rain approaches rapidly 2 In(d(0)/d) as plastic deformation develops from t he notch root; this 2 In(d(0)/d) is the average axial strain at the net sec tion at deformation levels where elastic deformation is negligible compared with the plastic one. The value of the new SNCF increases with plastic def ormation from the notch root and then decreases gradually. It becomes less than its elastic value at large deformations; however, it is larger than un ity at any deformation level. This is consistent with the concave distribut ions of axial strain at the net section. On the other hand, the value of th e conventional SNCF becomes less than unity after plastic deformation devel ops from the notch root. This is contradictory to the concave distributions of axial strain. The new SNCF is greater than the conventional value at an y deformation level. The new SNCF approaches the conventional SNCF as the s tress triaxiality decreases at the net section. The proposed SNCF is more r easonable than the conventional SNCF.