A fatigue model for sensitive materials to non-proportional loadings

• A new fatigue model is proposed.
• This model directly takes into account the loading non-proportionality in fatigue life prediction.
• The fatigue model is proposed in two equations for two tensile and shear cracking failure modes.
• The model was validated against several experimental datasets including different materials.
• The results were strongly correlated with the experimental data indicating accuracy of the model.

The present study proposes a novel fatigue model based on virtual strain energy. This model separates loading paths based on their non-proportionality where directly takes into account the loading in fatigue life prediction. The proposed fatigue model is expressed in two tension-based and shear-based equations for two tensile and shear cracking failure modes. The model was validated against several experimental datasets available in the literature. In addition, obtained results were compared to predicted lives through some well-known fatigue models comprising maximum shear strain, Smith–Watson–Topper, and Fatemi–Socie. The results were strongly correlated with the experimental data indicating accuracy of the model.