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Title: Influence of Drawbeads in Deep-Drawing of Plane-Strain Channel Sections: Experimental and FE Analysis

Abstract

The main purpose of the 'Numisheet'05 Benchmark no. 3: Channel Draw/Cylindrical Cup' was to evaluate the forming characteristics of materials in multi-stage processes. The concept was to verify the strain fields achieved during the two stage forming process and also to test the ability of numerical models to predict both strain and stress fields. The first stage consisted of forming channel sections in an industrial-scale channel draw die. The material that flows through the drawbead and over the die radii into the channel sidewalls is prestrained by cyclic bending and unbending. The prestrained channel sidewalls are subsequently cut and subjected to near plane-strain Marciniak-style cup test. This study emphasizes the analysis of the first stage process, the Channel Draw, since accurate numerical results for the first stage forming and springback are essential to guarantee proper initial state variables for the subsequent stage simulation. Four different sheet materials were selected: mild steel AKDQ-HDG, high strength steel HSLA-HDG, dual phase steel DP600-HDG and an aluminium alloy AA6022-T43. The four sheet materials were formed in the same channel draw die, but with drawbead penetrations of 25%, 50% and 100%. This paper describes the testing and measurement procedures for the numerical simulation of thesemore » conditions with DD3IMP FE code. A comparison between experimental and numerical simulation results for the first stage is presented. The experimental results indicate that an increase in drawbead penetration is accompanied by a general decrease in springback, with both sidewall radius of curvature and the sidewall angle increasing with increasing drawbead penetration. An exception to this trend occurs at the shallowest bead penetration: the radius of curvature in the sidewall is larger than expected. The sequence of cyclic tension and compression is numerically studied for each drawbead penetration in order to investigate this phenomenon.« less

Authors:
; ;  [1];  [2]; ;  [3]
  1. CEMUC, Department of Mechanical Engineering, University of Coimbra, Polo II, Rua Luis Reis Santos, Pinhal de Marrocos, 3030-788 Coimbra (Portugal)
  2. Department of Mechanical Engineering, University of Minho, Campus de Azurem, 4800-058 Guimaraes (Portugal)
  3. Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, Ontario, N9B 3P4 (Canada)
Publication Date:
OSTI Identifier:
21061766
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 908; Journal Issue: 1; Conference: NUMIFORM 2007: 9. international conference on numerical methods in industrial forming processes, Porto (Portugal), 17-21 Jun 2007; Other Information: DOI: 10.1063/1.2740915; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ALLOYS; AUGMENTATION; CARBON STEELS; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; CYLINDRICAL CONFIGURATION; D CODES; DRAWING; FINITE ELEMENT METHOD; STRAINS

Citation Formats

Oliveira, M. C., Baptista, A. J., Menezes, L. F., Alves, J. L., Green, D. E., and Ghaei, A. Influence of Drawbeads in Deep-Drawing of Plane-Strain Channel Sections: Experimental and FE Analysis. United States: N. p., 2007. Web. doi:10.1063/1.2740915.
Oliveira, M. C., Baptista, A. J., Menezes, L. F., Alves, J. L., Green, D. E., & Ghaei, A. Influence of Drawbeads in Deep-Drawing of Plane-Strain Channel Sections: Experimental and FE Analysis. United States. doi:10.1063/1.2740915.
Oliveira, M. C., Baptista, A. J., Menezes, L. F., Alves, J. L., Green, D. E., and Ghaei, A. Thu . "Influence of Drawbeads in Deep-Drawing of Plane-Strain Channel Sections: Experimental and FE Analysis". United States. doi:10.1063/1.2740915.
@article{osti_21061766,
title = {Influence of Drawbeads in Deep-Drawing of Plane-Strain Channel Sections: Experimental and FE Analysis},
author = {Oliveira, M. C. and Baptista, A. J. and Menezes, L. F. and Alves, J. L. and Green, D. E. and Ghaei, A.},
abstractNote = {The main purpose of the 'Numisheet'05 Benchmark no. 3: Channel Draw/Cylindrical Cup' was to evaluate the forming characteristics of materials in multi-stage processes. The concept was to verify the strain fields achieved during the two stage forming process and also to test the ability of numerical models to predict both strain and stress fields. The first stage consisted of forming channel sections in an industrial-scale channel draw die. The material that flows through the drawbead and over the die radii into the channel sidewalls is prestrained by cyclic bending and unbending. The prestrained channel sidewalls are subsequently cut and subjected to near plane-strain Marciniak-style cup test. This study emphasizes the analysis of the first stage process, the Channel Draw, since accurate numerical results for the first stage forming and springback are essential to guarantee proper initial state variables for the subsequent stage simulation. Four different sheet materials were selected: mild steel AKDQ-HDG, high strength steel HSLA-HDG, dual phase steel DP600-HDG and an aluminium alloy AA6022-T43. The four sheet materials were formed in the same channel draw die, but with drawbead penetrations of 25%, 50% and 100%. This paper describes the testing and measurement procedures for the numerical simulation of these conditions with DD3IMP FE code. A comparison between experimental and numerical simulation results for the first stage is presented. The experimental results indicate that an increase in drawbead penetration is accompanied by a general decrease in springback, with both sidewall radius of curvature and the sidewall angle increasing with increasing drawbead penetration. An exception to this trend occurs at the shallowest bead penetration: the radius of curvature in the sidewall is larger than expected. The sequence of cyclic tension and compression is numerically studied for each drawbead penetration in order to investigate this phenomenon.},
doi = {10.1063/1.2740915},
journal = {AIP Conference Proceedings},
number = 1,
volume = 908,
place = {United States},
year = {Thu May 17 00:00:00 EDT 2007},
month = {Thu May 17 00:00:00 EDT 2007}
}
  • Springback phenomenon associated with the elastic properties of sheet metals makes the design of forming dies a complex task. Thus, to develop consistent algorithms for springback compensation an accurate prediction of the amount of springback is mandatory. The numerical simulation using the finite element method is consensually the only feasible method to predict springback. However, springback prediction is a very complicated task and highly sensitive to various numerical parameters of finite elements (FE), such as: type, order, integration scheme, shape and size, as well the time integration formulae and the unloading strategy. All these numerical parameters make numerical simulation ofmore » springback more sensitive to numerical tolerances than the forming operation. In case of an unconstrained cylindrical bending, the in-plane to thickness FE size ratio is more relevant than the number of FE layers through-thickness, for the numerical prediction of final stress and strain states, variables of paramount importance for an accurate springback prediction. The aim of the present work is to evaluate the influence of the refinement of a 3-D FE mesh, namely the in-plane mesh refinement and the number of through-thickness FE layers, in springback prediction. The selected example corresponds to the first stage of the 'Numisheet'05 Benchmark no. 3', which consists basically in the sheet forming of a channel section in an industrial-scale channel draw die. The physical drawbeads are accurately taken into account in the numerical model in order to accurately reproduce its influence during the forming process simulation. FEM simulations were carried out with the in-house code DD3IMP. Solid finite elements were used. They are recommended for accuracy in FE springback simulation when the ratio between the tool radius and blank thickness is lower than 5-6. In the selected example the drawbead radius is 4.0 mm. The influence of the FE mesh refinement in springback prediction is discussed, for this example where the drawbead restraining force results in a non-symmetrical through-thickness stress gradient.« less
  • In industrial practice, variations in the steelmaking process may cause significant change in inclusion characteristics. During hot rolling of flat steel products, manganese sulfides, which are plastic at elevated temperatures, are elongated in the rolling direction. These elongated inclusions affect the formability properties, such as ductility, strain hardening exponent, average plastic strain ratio, critical strain represented by the forming limit diagram, and Charpy V-notch (CVN) impact energy as well as fracture behavior. The inclusion characteristics and microstructural features of three commercially produced hot-rolled deep-drawing quality steels were evaluated and their effects on formability and impact properties were investigated. All threemore » heats were made in a basic oxygen furnace. Two heats were teemed into ingots while the other heat was argon purged and continuous cast. These heats were then processed into 3.10 mm thick strips with identical processing parameters. Manganese sulfide stringers were found to reduce the transverse ductility, whereas yield and tensile strengths remained virtually the same in all directions. The formability parameters were not significantly affected by small variations in inclusion characteristics. However, CVN impact energy and impact transition temperature data were observed to improve with steel cleanliness. The sulfide stringers were also found to adversely affect the impact energy, transition temperature, and fracture behavior in the transverse direction.« less
  • Microscopic examination and microstructural analysis of vertical cracking phenomena in deep-drawn cups of hot-rolled SG295 steel strips were carried out in this study. Microvoids initiated preferentially at grain-boundary carbides were observed to form intergranular cracks. These grain-boundary carbides were identified as (Fe,Mn){sub 3}C carbides. The morphology of carbides was varied with processing variables, e.g., killing method and coiling temperature. In the Al-killed steels, the carbide shape tends to change from film type to bulk type, which may be beneficial to elongation and consequently formability. In addition, as the coiling temperature increased, the amount of banded pearlite structures and bulk-type carbidesmore » increased. These findings suggest that the deep drawability can be improved by modifying the carbide morphology in the microstructures.ss« less
  • It is well known that the macroscopic anisotropy and formability of a sheet metal are significantly affected by the crystallographic texture. So it is very important to find texture evolution rule in metal forming processes. In this paper, a rate-independent polycrystalline plasticity model is developed and introduced into dynamic explicit element method. Metal flow is assumed to occur by crystallographic slip on given slip systems within each crystal. Every integration point is a single crystal. Then the stability of ideal orientations and texture evolution of polycrystal are investigated.
  • The purpose of this study is to analyze and test a possible increase of the Limit Drawing Ratio (LDR) in Deep Drawing by Hydro-rim process (a certain subset of the classical Hydroforming) which includes the newly differential temperature effect. The idea is to facilitate the plastic flow by local heating along the flange and to cool the area where strength is needed. The suggested analysis is based on the dual bounds approach (upper and lower bounds simultaneously) using the highly versatile Johnson-Cook constitutive material model. The advantage of combined high hydraulic pressure (about 1000 bar) with relatively high blank temperaturemore » (with magnitude of about one third the melting temperature of the considered material) in the same operation is discussed. Emphasis is given to the rule of blank temperature difference (between the flange and the wall of the product) conjugate with optimal hydro rim pressure in increasing the limit drawing ratio of the products (Aluminum, Copper and various Steels)« less