skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Prediction Of Formability In Sheet Metal Forming Processes Using A Local Damage Model

Abstract

The formability in sheet metal forming processes is mainly conditioned by ductile fracture resulting from geometric instabilities due to necking and strain localization. The macroscopic collapse associated with ductile failure is a result of internal degradation described throughout metallographic observations by the nucleation, growth and coalescence of voids and micro-cracks. Damage influences and is influenced by plastic deformation and therefore these two dissipative phenomena should be coupled at the constitutive level. In this contribution, Lemaitre's ductile damage model is coupled with Hill's orthotropic plasticity criterion. The coupling between damaging and material behavior is accounted for within the framework of Continuum Damage Mechanics (CDM). The resulting constitutive equations are implemented in the Abaqus/Explicit code, for the prediction of fracture onset in sheet metal forming processes. The damage evolution law takes into account the important effect of micro-crack closure, which dramatically decreases the rate of damage growth under compressive paths.

Authors:
 [1]; ; ;  [2];  [2];  [3]
  1. INEGI, Inst. of Mech. Engineering. and Indust. Management, R. Barroco 174, 4465-591 Leca do Balio (Portugal)
  2. FEUP, Faculty of Engineering, University of Porto, R. Dr. Roberta Frias, 4200-465 Porto (Portugal)
  3. (Portugal)
Publication Date:
OSTI Identifier:
21057378
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 908; Journal Issue: 1; Conference: NUMIFORM '07: 9. international conference on numerical methods in industrial forming processes, Porto (Portugal), 17-21 Jun 2007; Other Information: DOI: 10.1063/1.2740804; (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; A CODES; ALLOYS; COALESCENCE; COMPUTERIZED SIMULATION; CRACK PROPAGATION; CRACKS; DAMAGE; DUCTILITY; FRACTURES; METALS; NUCLEATION; PLASTICITY; SHEETS; STRAINS; VOIDS

Citation Formats

Teixeira, P., Santos, Abel, Cesar Sa, J., Andrade Pires, F., Barata da Rocha, A., and INEGI, Inst. of Mech. Engineering. and Indust. Management, R. Barroco 174, 4465-591 Leca do Balio. Prediction Of Formability In Sheet Metal Forming Processes Using A Local Damage Model. United States: N. p., 2007. Web. doi:10.1063/1.2740804.
Teixeira, P., Santos, Abel, Cesar Sa, J., Andrade Pires, F., Barata da Rocha, A., & INEGI, Inst. of Mech. Engineering. and Indust. Management, R. Barroco 174, 4465-591 Leca do Balio. Prediction Of Formability In Sheet Metal Forming Processes Using A Local Damage Model. United States. doi:10.1063/1.2740804.
Teixeira, P., Santos, Abel, Cesar Sa, J., Andrade Pires, F., Barata da Rocha, A., and INEGI, Inst. of Mech. Engineering. and Indust. Management, R. Barroco 174, 4465-591 Leca do Balio. Thu . "Prediction Of Formability In Sheet Metal Forming Processes Using A Local Damage Model". United States. doi:10.1063/1.2740804.
@article{osti_21057378,
title = {Prediction Of Formability In Sheet Metal Forming Processes Using A Local Damage Model},
author = {Teixeira, P. and Santos, Abel and Cesar Sa, J. and Andrade Pires, F. and Barata da Rocha, A. and INEGI, Inst. of Mech. Engineering. and Indust. Management, R. Barroco 174, 4465-591 Leca do Balio},
abstractNote = {The formability in sheet metal forming processes is mainly conditioned by ductile fracture resulting from geometric instabilities due to necking and strain localization. The macroscopic collapse associated with ductile failure is a result of internal degradation described throughout metallographic observations by the nucleation, growth and coalescence of voids and micro-cracks. Damage influences and is influenced by plastic deformation and therefore these two dissipative phenomena should be coupled at the constitutive level. In this contribution, Lemaitre's ductile damage model is coupled with Hill's orthotropic plasticity criterion. The coupling between damaging and material behavior is accounted for within the framework of Continuum Damage Mechanics (CDM). The resulting constitutive equations are implemented in the Abaqus/Explicit code, for the prediction of fracture onset in sheet metal forming processes. The damage evolution law takes into account the important effect of micro-crack closure, which dramatically decreases the rate of damage growth under compressive paths.},
doi = {10.1063/1.2740804},
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}
}
  • A closed form analytical model for the prediction of strain space formability as a function of temperature and strain rate is proposed. The analytical results are compared with experimental observations. For plane strain conditions, good correlation is reported. This work is significant to those aiming to incorporate formability models directly into numerical simulation programs for the purpose of design and analysis of products manufactured through the warm forming process.
  • In this study, we studied formability of PET/PVC laminated sheet metal which named VCM (Vinyl Coated Metal). VCM offers various patterns and good-looking metal steel used for appliances such as refrigerator and washing machine. But, this sheet has problems which are crack and peeling of film when the material is formed by deep drawing process. To predict the problems, we used finite element method and GTN (Gurson-Tvergaard-Needleman) damage model to represent damage of material. We divided the VCM into 3 layers (PET film, adhesive and steel added PVC) in finite element analysis model to express the crack and peeling phenomenon.more » The material properties of each layer are determined by reverse engineering based on tensile test result. Furthermore, we performed the simple rectangular deep drawing and simulated it. The simulation result shows good agreement with drawing experiment result in position, punch stroke of crack occurrence. Also, we studied the fracture mechanism of PET film on VCM by comparing the width direction strain of metal and PET film.« less
  • Ductile (or plastic) damage often occurs during sheet metal forming processes due to the large plastic flow localization. Accordingly, it is crucial for numerical tools, used in the simulation of that processes, to use fully coupled constitutive equations accounting for both hardening and damage. This can be used in both cases, namely to overcome the damage initiation during some sheet metal forming processes as deep drawing, ... or to enhance the damage initiation and growth as in sheet metal cutting. In this paper, a fully coupled constitutive equations accounting for combined isotropic and kinematic hardening as well as the ductilemore » damage is implemented into the general purpose Finite Element code for metal forming simulation. First, the fully coupled anisotropic constitutive equations in the framework of Continuum Damage Mechanics are presented. Attention is paid to the strong coupling between the main mechanical fields as elasto-viscoplasticity, mixed hardening, ductile isotropic damage and contact with friction. The anisotropy of the plastic flow is taken into account using various kinds of quadratic or non quadratic yield criteria in the framework of non associative finite plasticity theory with two types of normality rules. The associated numerical aspects concerning both the local integration of the coupled constitutive equations as well as the (global) equilibrium integration schemes are presented. The local integration is outlined thanks to the Newton iterative scheme applied to a reduced system of 2 equations. For the global resolution of the initial and boundary value problem, the classical dynamic explicit (DE) scheme with an adaptive time step control is used. The numerical implementation of the damage is made in such a manner that calculations can be executed with or without damage effect, i.e. fully coupled or uncoupled calculations. For the 2D processes an advanced adaptive meshing procedure is used in order to enhance the numerical solution and to kill the fully damaged elements in order to describe the macroscopic crack propagation. Various 2D and 3D examples are given in order to show the capability of the methodology to predict the damage initiation and growth during various sheet metal forming processes.« less
  • Two types of anisotropy have been introduced in the Marciniak model for the prediction of forming limit diagrams (FLDs) of sheet material. One type is due to crystallographic texture, the other is due to dislocation substructure. First, an anisotropic plastic potential is derived from a measured crystallographic texture using a multilevel model. The yield locus can be derived from this plastic potential. In addition to this, a model is used to simulate microstructure-induced work hardening and softening. This model can take effects of strain path changes into account. Both the texture-based and microstructure-based anisotropic model are then implemented in themore » Marciniak model and used for FLD calculation. Examples of application are given for IOF steel and for aluminium alloys. Recent research has focused on the physical basis of the microstructure-induced work hardening and softening. The principles of this model will be elucidated.« less
  • In this study, a modified Johnson-Cook (J-C) model and an innovated method to determine (J-C) material parameters are proposed to predict more correctly stress-strain curve for tensile tests in elevated temperatures. A MATLAB tool is used to determine material parameters by fitting a curve to follow Ludwick's hardening law at various elevated temperatures. Those hardening law parameters are then utilized to determine modified (J-C) model material parameters. The modified (J-C) model shows the better prediction compared to the conventional one. As the first verification, an FEM tensile test simulation based on the isotropic hardening model for boron sheet steel atmore » elevated temperatures was carried out via a user-material subroutine, using an explicit finite element code, and compared with the measurements. The temperature decrease of all elements due to the air cooling process was then calculated when considering the modified (J-C) model and coded to VUMAT subroutine for tensile test simulation of cooling process. The modified (J-C) model showed the good agreement between the simulation results and the corresponding experiments. The second investigation was applied for V-bending spring-back prediction of magnesium alloy sheets at elevated temperatures. Here, the combination of proposed J-C model with modified hardening law considering the unusual plastic behaviour for magnesium alloy sheet was adopted for FEM simulation of V-bending spring-back prediction and shown the good comparability with corresponding experiments.« less