A multiplicative plastic hardening model in consideration of strain softening and strain rate: Theoretical derivation and characterization of model parameters with simple tension and creep test. (1st December 2020)

• Record Type: Journal Article
• Authors: Kim, Hyunki; Yoon, Jeong Whan; Chung, Kwansoo; Lee, Myoung-Gyu
• Is Part Of: International journal of mechanical sciences. Volume 187(2020)
• Publication Date: 2020-12-01
• Subjects: Hardening deterioration -- Softening -- Creep test -- Strain rate sensitivity -- Inverse identification -- Magnesium alloys; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2020.105913
• Languages: English
• ISSNs: 0020-7403

Abstract

Highlights: An identification process for hardening behavior of AZ61 mg alloy sheet after uniform deformation limit and strain rate sensitivity of metals at elevated temperatures are investigated. The new inverse identification procedure utilizes creep tests to avoid non-uniqueness problem in the tension test based approach. Analytical and numerical creep models are newly developed for the generalized multiplicative constitutive law accounting for hardening, softening, and strain rate sensitivity. The proposed approach is validated by comparing the calculated stress-strain curves and creep strains under different strain rates and prior creep strains with experiments. Abstract: Hardening behavior with its ultimate deterioration (or softening) after uniform deformation limit and strain rate sensitivity of metals at elevated temperatures are characterized. To avoid non-uniqueness in the identification procedure based on only simple tension test, an inverse identification procedure involving not only the simple tension test, but also the creep test is newly proposed. Moreover, for better understanding of creep behavior, analytical and numerical creep models are developed for the generalized multiplicative constitutive law accounting for hardening, softening, and strain rate sensitivity. Robust parametric studies are presented to explore the effect of material and process parameters on creep deformation behavior, which is also effectively used for the two-step characterization procedure of the proposed hardening model. The identification procedure for the multiplicative constitutive model is demonstrated using AZ61 Mg alloy sheet, which provides good correlations between calculated and measured stress-strain curves and creep strains under different strain rates and prior-creep strains. Graphical abstract: Image, graphical abstract