Multiaxial fatigue damage parameter and life prediction under low cycle loading for GH4169 alloy and other structural materials

Combined tension–torsion fatigue tests were conducted on nickel-based alloy GH4169 under proportional and nonproportional loading at 650 °C. The fatigue cracks on the specimen surface were found basically initiating and propagating along the maximum shear plane. Taking into account the materials in elastic–plastic state under low-cycle fatigue, a multiaxial fatigue damage parameter based on SW model was proposed. The developed damage model can be reduced to the uniaxial Manson–Coffin equation, which was used to evaluate the low cycle multiaxial fatigue for GH4169 alloy, Haynes188 and mild steel. It is concluded that the predicted results with the proposed model can give satisfied results.