Fatigue life prediction under variable amplitude axial–torsion loading using maximum damage parameter range method

• A maximum damage parameter range (MDPR) reversal counting method is proposed.
• Fatigue damage parameter will be directly defined as cycle counting parameter.
• Based on MDPR method, a fatigue life prediction procedure is proposed.
• The detailed algorithm is proposed.
• The proposed method can provide satisfactory prediction.

This article deals with the problem of multiaxial fatigue life assessment under variable amplitude axial–torsion loading. A maximum damage parameter range (MDPR) reversal counting method is proposed to predict fatigue life under variable amplitude multiaxial loading. First, a multiaxial fatigue damage parameter is selected for a given multiaxial loading time history. Then, a damage parameter range time history can be calculated. Finally, based on the MDPR method, fatigue life can be predicted by correlating with multiaxial fatigue damage model and the Miner–Palmgren damage rule. The proposed method is evaluated with experimental data of the 7050-T7451 aluminum alloy and En15R steel under variable amplitude multiaxial loading. The results demonstrated that the proposed method can provide satisfactory prediction.