Formability analysis of pre-strained AA5754-O sheet metal using Yld96 plasticity theory: Role of amount and direction of uni-axial pre-strain. (October 2016)

• Record Type: Journal Article
• Authors: Dhara, S.; Basak, S.; Panda, S.K.; Hazra, S.; Shollock, B.; Dashwood, R.
• Is Part Of: Journal of manufacturing processes. Volume 24:Part 1(2016)
• Page Start: 270
• Page End: 282
• Publication Date: 2016-10
• Subjects: σ-FLD stress based forming limit diagram -- ε-FLD strain based forming limit diagram -- UT uni-axial tensile test -- UP uni-axial pre-strain -- SC stack compression test -- UTS ultimate tensile strength -- YS yield strength -- LDH limiting dome height; AA5754-O -- Uni-axial pre-strain -- Forming limit diagram -- Limiting dome height -- Yld96 anisotropic yield theory -- Finite element model; Production management -- Data processing -- Periodicals; Manufacturing processes -- Periodicals; Procestechnologie; Productietechniek; Production -- Gestion -- Informatique -- Périodiques; Fabrication -- Périodiques; Manufacturing processes; Production management -- Data processing; Periodicals; 670.5
• DOI: 10.1016/j.jmapro.2016.09.014
• Languages: English
• ISSNs: 1526-6125

Abstract

Graphical abstract: Highlights: Formability of different uni-axial pre-strained AA5754-O material was compared. Yld96 plasticity theory predicted the yield evolution of pre-strained materials. Dynamic shifts of ε-FLDs of pre-strained sheets were predicted by decoupling σ-FLD. LDH of pre-strained materials was successfully predicted using σ-FLD. Effect of direction of prestrain on LDH and thickness distribution was negligible Abstract: Automotive industries are very much interested in formability of different pre-strained aluminum alloy sheets in the context of multistage stamping to fabricate complex components. In the present work, different uni-axial pre-strains of 6.4% and 12.2% were induced in AA5754-O aluminum alloy both along rolling direction (RD) and transverse direction (TD). The true stress-strain response, limiting dome height (LDH) and strain based forming limit diagram (ε-FLD) of as received and all pre-strained materials were evaluated experimentally. The anisotropy constitutive material model was developed using the Yld96 plasticity theory in-conjunction with the Hollomon isotropic hardening law to predict the yield strength evolution of the pre-strained materials. Also, it was found that the limiting strains in ε-FLD shifted significantly depending on the amount and direction of uni-axial pre-strain. Hence, the limiting strains of the as-received materials were transposed into stress space to estimate the stress based forming limit diagram (σ-FLD) using the anisotropy constitutive material model. Further, the dynamic shifts of ε-FLDs of four different pre-strained materials were predicted by successfully decoupling the σ-FLD of as-received materials within root mean square error of 0.008. Finite element models of both uni-axial pre-straining and subsequent LDH tests were developed, and the forming behavior of the pre-strained materials were predicted implementing the Yld96 plasticity model and estimated σ-FLD. It was found that LDH was significantly influenced by the amount of pre-strain, and the maximum thinning location shifted close to pole in the case of 12.2% pre-strained materials. However, the effect of uni-axial pre-strain direction on both LDH and maximum thinning location in AA5754-O material was very negligible.