eva‎luation of low-cycle fatigue of notched metal specimens considering cyclic plasticity using continuum damage mechanics

3/6/2024 12:00:00 AM

Fatigue is one of the most important and complex phenomena in component failure, for which considerable effort has been made to predict and control. Fatigue is divided into two types, low-cycle and high-cycle fatigue regims, according to the number of cycles to failure. One of the important issues is predicting life on the border of low-cycle and high-cycle fatigue. Pandey's damage model was used to predict the life of components on the border of low-cycle and high-cycle fatigue to check the accuracy of the model in this area. This damage model only needs strain-life diagram and damage propagation-cycle diagram to obtain constants that are obtained from the fully reversed strain control tension-compression uniaxial test. To simulate and validate the damage model, the UMAT subroutine was developed in Abaqus finite element code. Radial return method was used to calculate stress and strain in the plastic region and Newton-Raphson method was used to solve the equations. As the material enters the plastic region, kinematic and isotropic hardening is included in the code; However, due to the lack of isotropic hardening behavior in the desired material, isotropic hardening was omitted. The developed code was implemented on a notched specimen under tension-tension and tension-compression loading, and the results were compared with experimental values and damage models of Chaboche and Lesne, and Dufailly and Lemaitre damage; that the error of the obtained results for tension-tension loading was less than 30% and for tension-compression less than 50%, which was acceptable. In the end, Chaboche and Prager hardening were compared. The Chaboche hardening was able to predicte life better than the Prager hardening, but the results of the Prager hardening were also acceptable, and due to the simpler coding of Prager hardening, Prager hardening can also be used to predict life.

خستگي , پلاستيسيته چرخه‌اي , خستگي كم چرخه , خستگي پرچرخه , پيش‌بيني عمر , مكانيك آسيب پيوسته , قطعه شياردار

fatigue , Cyclic plasticity , low cycle fatigue , High Cycle Fatigue , Life prediction , Continuous damage mechanics , Notched specimen

Mohammad Amin Farzanniya

Dr. Hadi Khorami Shad