The energy approach in the calculation of fatigue lives under non-proportional bending with torsion

The paper contains the results of fatigue tests of 10HNAP steel under non-proportional random bending with torsion. The circular smooth specimens were tested. The tests performed in the high cycle fatigue regime. The method identifies strain energy density parameter in the critical fracture plane through integration of chosen portions of power history according to the distinguished ranges of stresses. In the scatter bands of the factors of 2 and 3 proposed method gives as satisfactory results as it does for constant-amplitude cyclic tests.