Abstract: A new strength criterion, named the distortion-dilatation (D-D) criterion, is proposed that considers the competition between distortion and dilatation during material failure. The stress form of this D-D criterion conforms to an elliptical equation, while the energy form is a linear equation. For the first time, molecular dynamics simulations with triaxial loading are applied to systematically study the failure of four types of typical metals, including nanocrystalline Ni, Fe, Ti, and amorphous Cu₆₄Zr₃₆, at different temperatures, resulting in various critical failure stresses. The molecular dynamics simulation results align closely with the D-D criterion, demonstrating its rationality and applicability. Furthermore, the D-D criterion is applied to predict the critical failure stresses of FeNiCrCoCu high-entropy alloy, showing high prediction accuracy. This new strength criterion is expected to be integrated into finite element analysis, offering a more accurate evaluation of the service safety of engineering components under complex mechanical loads.

Key words: Distortion, Dilatation, Strength criterion, Molecular dynamics, High-entropy alloy