Advanced constitutive model for repeated stress relaxation accounting for transient mobile dislocation density and internal stress. (June 2019)

• Record Type: Journal Article
• Authors: Varma, Anand; Krishnaswamy, Hariharan; Jain, Jayant; Lee, Myoung-Gyu; Barlat, Frédéric
• Is Part Of: Mechanics of materials. Volume 133(2019)
• Page Start: 138
• Page End: 153
• Publication Date: 2019-06
• Subjects: Repeated stress relaxation -- Activation volume -- Dislocation density model; Strength of materials -- Periodicals; Mechanics, Applied -- Periodicals; Résistance des matériaux -- Périodiques; Mécanique appliquée -- Périodiques; Mechanics, Applied; Strength of materials; Periodicals; Electronic journals; 620.11
• DOI: 10.1016/j.mechmat.2019.03.009
• Languages: English
• ISSNs: 0167-6636

Abstract

Highlights: A new phenomenological model for stress relaxation is proposed. Variation of mobile dislocation density is mathematically and physically consistent with the experimental data. Dislocation density models are utilized for the first time to model the evolution of internal stress in the stress relaxation modeling approach. Strain hardening and mobile dislocation density are decoupled during stress relaxation. The bounds of strain hardening effect on internal stress during relaxation is established from the dislocation density model. Abstract: Repeated stress relaxation tests are used to characterize the macroscopic time dependent behavior in metals. During stress relaxation, the mobile dislocation density and internal stress vary continuously with time. The phenomenological models available do not provide a comprehensive mathematical framework to account for transient effects during stress relaxation accurately. An advanced stress relaxation model based on the logarithmic model is proposed in the present work to overcome the limitations of existing models. The proposed model is found to fit the experimental data of SS 316 better than the available models. The proposed model in combination with Kocks–Mecking type dislocation density model is utilized to predict the rate of strain hardening during relaxation