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 Allom 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 stressstrain 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.