Biaxial fatigue of stainless steel 304 under irregular loading

Fatigue tests are performed on tubular specimens of stainless steel 304 under variable amplitude, irregular axial-torsional loading. Three parameters are chosen for correlating fatigue life: the Smith-Watson-Topper (SWT) parameter for normal fracture, Fatemi-Socie (FS), and Kandil-Brown-Miller parameters (KBM) for shear fracture. A life computation procedure is employed in which rainflow cycle counting on normal (SWT) or shear (FS, KBM) strain history and the Miner-Palmgren rule are used. It is found that, while the life calculation procedure appears to be viable and each parameter yields acceptable results for most loading conditions, there are cases for which correlation is poor. The SWT parameter performed well except for torsion-dominated cycles, where it overpredicted lives. The FS and KBM parameters did better than the SWT parameter in torsion, but showed poor performance in some other loading conditions.