Abstract
Multiaxial fatigue life prediction under irregular loading is studied on two materials exhibiting shear fracture(SNM440, SNCM630). Fatigue tests are conducted at room temperature under tension-torsion, proportional and nonproportional loading with constant and variable amplitudes. The Kandil-Brown-Miller (KBM) parameter, the Smith-Watson-Topper (SWT) parameter and an energy-based parameter are used with the rainflow cycle counting method and Miner's rule of damage accumulation. The fatigue life is calculated based on the strain profiles on the critical plane for the KBM and SWT parameters and based on the maximum damage for the energy parameter. The energy-based parameter is found to provide best correlation with experimental lives. It was also found that the normal strain on the maximum shear strain plane does not affect fatigue life of SCM440 significantly.
