Fatigue life of metallic material estimated according to selected models and load conditions

The authors present results of a fatigue test for specimens made of the aluminium alloy 2017A-T4 and alloy steels S355J2WP and S355J2G3 subjected to constant-amplitude proportional combined bending with torsion including mean stress values and for the S355J2WP alloy steel under uniaxial constant-amplitude and random loading with both zero and non-zero mean stress values. The test results were compared with the results of calculations according to the models proposed by Goodman, Gerber and Morrow as well as the stress-strain parameter. In the case of calculations based on the stresses, the multiaxial stress state was reduced to a uniaxial one using the Huber-Mises relationship. As for the method based on strain energy density, the multiaxial stress state was reduced to the uniaxial one with use of the stress-strain parameter. The plane in which the stress-strain parameter of shear loadings reaches its maximum value is assumed to be the critical plane.