A Generalized Ellipse Criterion for High‐Strength Steels Under Multiaxial and Uniaxial Fatigue Across Stress Ratios

ABSTRACT Fatigue failure in engineering components predominantly occurs under multiaxial stress conditions. The complexity and high cost of multiaxial fatigue tests necessitate a robust equivalent stress principle capable of predicting multiaxial fatigue performance from readily available uniaxial data. However, existing principles lack generality for high‐strength steels across various conditions. This study compiles 44 stress conditions and evaluates prevailing approaches. The critical plane data indicate that a quadratic combination of shear and normal stresses with a sign correction distinguishing tension from compression is essential, and the fatigue strength data reveal that the normal stress parameter must be redefined to incorporate both amplitude and mean contributions through a weighted linear sum, rather than relying on its maximum alone. These findings yield a generalized equivalent stress principle serving dually as a critical plane identifier and a fatigue strength predictor for various loading scenarios, offering significant practical utility for the design of high‐strength steel components.