Fatigue life of steel under synchronous and asynchronous combined bending and torsion with variable amplitudes according to criteria of biaxial random fatigue

Fatigue lives, calculated according to three criteria of multiaxial random fatigue, were compared with lives obtained from tests of cylindrical specimens made of SOCrNiMoS steel and subjected to synchronous and asynchronous combined bending and torsion with variable amplitudes. The expected fatigue fracture plane positions were determined with the aid of variance method. The equivalent stress histories were schematized with the rain flow method and fatigue damages were cumulated according to the Palmgren-Miner hypothesis.