PSI - Issue 43

Atri Nath et al. / Procedia Structural Integrity 43 (2023) 246–251 Author name / Structural Integrity Procedia 00 (2022) 000 – 000

251

6

due to the unloading and reverse loading that takes place during each branch in a cyclic loading. In the stress space, this corresponds to the translation of the elastic domain reflecting the description of the fast internal changes during each inelastic transient. The decomposition of the back stress into a rapidly saturated variable (the first backstress component α 1 ) and multiple quasi-linear components ( α i ; i=2,3,4) is associated with the separation of short-range and long-range interactions between defects at the various scales of the microstructure (Chaboche, 1986).

b

a

c Figure 5: Comparison of the stabilized magnitude of the different backstress of the KH component for various microstructures a) first backstress ( α 1 ) component, b) second backstress ( α 2 ) component, and c) fourth backstress ( α 4 ) component with threshold parameter ( a 4 ). 4. Conclusions This study examines a generalized approach to analyze the cyclic-plastic response of a wide variety of metallic materials considering Chaboche’s combined isotropic-kinematic hardening (CIKH) model. The proposed procedure determines the parameters of the cyclic-plastic model from the strain-controlled stabilized loops with a subsequent refinement of the model parameters using the Genetic Algorithm optimization technique. The study encompasses the prediction of symmetric strain-controlled hysteresis loops and ratcheting behaviour for six different ferrous and non ferrous materials having different crystal structures and varied responses in terms of cyclic-hardening/softening or stable behavior. The adopted approach provides a consistently low magnitude of the F error (<3%), for all the different materials under different loading conditions which illustrates the superior predictive capability in comparison to existing approaches, as well as depicts the generalized nature of the adopted approach. Finally, the parameters of the CIKH model obtained for the different materials are compared based on the crystal structure; the contribution of the nonlinear backstresses is more pronounced for the investigated BCC structured materials, while for closely-packed HCP structured material, the backstress evolution is largely linear. References Agius, D., Kourousis, K.I., Wallbrink, C., 2018. A modification of the multicomponent Armstrong – Frederick model with multiplier for the enhanced simulation of aerospace aluminium elastoplasticity. Int. J. Mech. Sci. 144, 118 – 133. Bari, S., Hassan, T., 2000. Anatomy of coupled constitutive models for ratcheting simulation. Int. J. Plast. 16, 381 – 409. Chaboche, J.L., 1991. On some modifications of kinematic hardening to improve the description of ratchetting effects. Int. J. Plast. 7, 661 – 678. Chaboche, J.L., 1986. Time-independent constitutive theories for cyclic plasticity. Int. J. Plast. 2, 149 – 188. Cheng, H., Chen, G., Zhang, Z.,Chen, X., 2015. Uniaxial ratcheting behaviors of Zircaloy- 4 tubes at 400 °c. J. Nucl. Mater. 458, 129– 137. Hassan, T., Kyriakides, S., 1992. Ratcheting in cyclic plasticity, part I: Uniaxial behavior. Int. J. Plast. 8, 91 – 116. Kan, Q.H., Yan, W.Y., Kang, G.Z., Guo, S.J., 2011. Experimental Observation on the Uniaxial Cyclic Deformation Behaviour of TA16 Titanium Alloy. Adv. Mater. Res. 415 – 417, 2318 – 2321. Kourousis, K. I., 2013. A cyclic plasticity model for advanced light metal alloys. App. Mech. Mat. 391, 3-8. Nath, A., Ray, K.K., Barai, S. V., 2019a. Evaluation of ratcheting behaviour in cyclically stable steels through use of a combined kinematic isotropic hardening rule and a genetic algorithm optimization technique. Int. J. Mech. Sci. 152, 138 – 150. Nath, A., Barai, S. V., Ray, K.K., 2019b. Prediction of asymmetric cyclic ‐ plastic behaviour for cyclically stable non ‐ ferrous materials. Fatigue Fract. Eng. Mater. Struct. 42, 2808 – 2822. Nath, A., Barai, S. V., Ray, K.K., 2019b. Estimation of cyclic hardening/softening and ratcheting response of materials through an algorithm to optimize parameters in Chaboche's hardening rule. Fatigue Fract. Eng. Mater. Struct. 45, 1847-1865. Paul, S.K., Sivaprasad, S., Dhar, S., Tarafder, M., Tarafder, S., 2010. Simulation of cyclic plastic deformation response in SA333 C – Mn steel by a kinematic hardening model. Comp. Mat. Sci. 48, 662-671. Zhang, J., Jiang, Y., 2008. Constitutive modeling of cyclic plasticity deformation of a pure polycrystalline copper. Int. J. Plast. 24, 1890 – 1915.