Earing Prediction in Drawing and Ironing Processes Using an Advanced Yield Criterion

Abstract

This work aims to contribute to the understanding of the role/influence of advanced yield criteria on the earing profile prediction after drawing and ironing, for a cylindrical cup benchmark proposed at the NUMISHEET 2011 conference [1]. Two typical materials used for can-making were considered and studied: an AA5042 aluminum alloy and an AKDQ steel. The drawing and ironing operations are performed on a special die which allows drawing and ironing in one single punch stroke in order to simplify the real process. The benchmark results report include, for each material: (i) the earing profile after drawing and ironing, presenting the cup height evolution with the angle from the rolling direction, and (ii) the evolution of punch force with punch stroke. This work presents a comparison between experimental and numerical results obtained for the aforesaid benchmark with DD3IMP in-house solver, using two sets of parameters for the Cazacu and Barlat 2001 [2] yield criterion, identified based on uniaxial tensile, equi-biaxial tension and disc compression test results. The first set uses the initial yield stress values while the second one used the flow stress values for an accumulated plastic work of 20 MPa. The results highlight the different impact of the experimental data in the earing prediction for both materials: the results for the second set are slightly improved for the AKDQ steel while for AA5042 the effect is negligible. The improved earing prediction obtained with the second set for the AKDQ steel seems to result from a better description of the stress states that occur in the flange zone.

Influence of the characteristics of the experimental data set used to identify anisotropy parameters

“…However, the conditions that guarantee the convexity of CB2001 are unknown. Therefore, following Soare et al [17], the minimisation process adopted includes testing the convexity of the yield surface for several planes in the stress space [34]. For metal sheets the parameters a 5 , a 6 and b k (k = 6, 7, 8, 9, 11) cannot be evaluated, thus the corresponding isotropy condition values are commonly adopted, i.e.…”

Plastic anisotropy and failure in thin metal: Material characterization and fracture prediction with an advanced constitutive model and polar EPS (effective plastic strain) fracture diagram for AA 3014-H19

“…Chung et al, 1997;Dick et al, 2007 ). Barros et al (2013) reported the accurate prediction of the earing during cup drawing depends not only on the correct modeling of the materials mechanical behavior but also on the accuracy of the global process modeling including the blank holder, the yield criterion selected, the work hardening law and the strategy used to identify the materials parameters. Neto et al (2016) studied the influence of elastic deformation of the tooling during cup drawing and concluded the accuracy of the sheet metal forming simulation can be improved considering the elastic deformation of the forming tools in the numerical model.…”

Influence of Uniaxial Deformation on Texture Evolution and Anisotropy of 3104 Al Sheet with Different Initial Microstructure

“…Rolling texture components favor earing principally at 45 • /135 • with respect to the RD [4,5]. With regards to earing, a low ear ratio can be achieved through an optimal combination of crystals with an orientation that results in both 45 • /135 • and 0 • /90 • ears [6][7][8][9]. The crystallographic components which are formed during recrystallization depend on the stacking fault energy (SFE), the previous deformation state, the annealing temperature as well as the precipitation state.…”