Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Modeling of Mean Stress Relaxation in Inconel 718 under Axial-Torsional Loading and Its Impact on Fatigue Life Prediction
Submission Author:
Vitor Nascimento , DF
Co-Authors:
Vitor Nascimento, Fábio Castro, Cainã Bemfica de Barros
Presenter: Vitor Nascimento
doi://10.26678/ABCM.COBEM2021.COB2021-0400
Abstract
The capability of the Jiang-Sehitoglu plasticity model to describe mean stress relaxation in Inconel 718, and its impact on fatigue life, is studied in this work. To this end, axial-torsional experimental data from Inconel 718 at room temperature is investigated. The constants of the model were determined from fully reversed and zero-tension axial test data using a nonlinear optimization tool. Half-life mean stresses under proportional and nonproportional loading were simulated and compared with their experimental counterparts to evaluate whether the plasticity model could describe the mean stress relaxation effect. The difference between simulated and observed axial mean stress ranged from -45 to 60% for most loading paths, while for the mean shear stress, the difference ranged from -35 to 35%. For the Chaboche model, which is a particular case of the Jiang–Sehitoglu model, when the exponent of the recovery term is zero, differences ranging from -100 to 65% were noticed for the axial mean stress and -100 to 30% for the mean shear stress. The Fatemi-Socie fatigue criterion was employed to determine the fatigue lives due to the shear cracking behavior of Inconel 718. The implication of considering mean stress relaxation in the fatigue life predictions resulted in life estimation within a factor-of-two boundaries for all loading conditions.
Keywords
Axial-Torsional Fatigue, Inconel 718, Mean Stress Relaxation, life prediction
