A1 Journal article (refereed), original research

Experimental fatigue characterization and finite element analysis of elasto-plastic behavior of notched specimens made of direct-quenched ultra-high strength steel


Publication Details
Authors: Dabiri Mohammad, Isakov Matti, Skriko Tuomas, Bjork Timo
Publication year: 2016
Language: English
Related Journal or Series Information: Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science
JUFO-Level of this publication: 1
Open Access: Not an Open Access publication

Abstract
The low-cycle fatigue behavior of a direct-quenched ultra-high-strength steel was experimentally characterized and numerically modeled. Fatigue and cyclic parameters were obtained by conducting strain-controlled low-cycle fatigue tests on uniform-gage specimens. Surface residual stresses were minimized and axial deflection eliminated by optimization of machining parameters and post-machining electro-polishing. The steel material showed cyclic softening and decrease in yield strength. Cyclic softening, stabilized response, and the cyclic stress-strain curve were numerically simulated using finite element analysis with a model capable of describing nonlinear kinematic-isotropic hardening. The results showed good agreement with experimental values and validated the model's ability to simulate the softening and cyclic stabilization of the material under investigation. The same numerical method was then used in elasto-plastic stress- strain analysis of notched specimens made of the same material to make fatigue life predictions. Estimated lives were compared with predictions made by analytical approximations such as the linear rule, Neuber's rule, and the strain energy density method and verified by experimental data. Finite element analysis using stabilized cyclic response yields the most accurate predictions and, thus, provides an effective tool for the fatigue analysis of this material.

Last updated on 2018-19-10 at 08:49