AbstractA multiaxial fatigue strain energy density parameter has been formulated which normalizes fatigue data obtained under a variety of mean stress levels and loading combinations. This parameter represents that proportion of the overall strain energy contributed by the stresses and strains on the critical or fracture plane. It is shown that multiaxial fatigue life data may be accurately correlated by applying this parameter to the experimental results of Inconel 718 alloy subjected to a variety of mean normal and shear stress levels, as well as to SAE 1045 steel tested under tension, torsion and simultaneous tension and torsion.