A numerical analysis of combined bending–torsion fatigue of SAE notched shaft

A notch analysis method using a finite element basis is integrated with two critical plane multiaxial fatigue criteria to simulate combined bending–torsion fatigue of SAE 1045 notched specimen. For both in-phase and out-of-phase loading tests, predictions were in accord with experimental results and mostly conservative. The relatively longer fatigue lives in out-of-phase tests were also simulated correctly in comparison with in-phase tests with identical bending and torsion amplitudes. The importance of locating the most critical material point was demonstrated and the need for finite element basis is concluded for an appropriate computational methodology even for relatively simple specimen geometry.