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Author(s): P. Teixeira
F. M. A. Pires
A. D. Santos
J. César Sá
A. Barata Rocha
Title: Modelling of fracture in sheet metal forming
Issue Date: 2008
Abstract: During the last decade, several commercial codes were developed to meet theincreasing demands from industry to evaluate deformation paths as well as forming defects,in order to avoid the long and expensive tryout in press shops. Although these numericalcodes have reached a high accuracy in the evaluation of forming defects, the accurateprediction of a necking initiation is still a largely open question. The traditional method forfailure prediction is to perform a comparison of the material points principal strains with theForming Limit Diagram, obtained under proportional in-plane loading. Although this kind ofanalysis is reliable for simple cases, when complex strain paths and anisotropy are involved,this approach may fail to give the right answer due to the strong dependence of the FormingLimit Diagram level in respect to the strain and stress history. Alternatively, prediction offailure for complex parts stamping can be made by post-processing the numerical solutionusing a Plastic Instability Model such as the widely used localization approach proposed byMarciniak and Kuczincki coupled with the conventional theory of Plasticity [1]. Anotherpromising approach is to consider a continuum damage model that describes the internalmaterial degradation due to micro-defects that occur during plastic loading and, therefore,can establish a limit for plastic deformation of a part in forming operations. Within thisframework, a continuum damage model is implemented in a commercial code, fully coupledwith an orthotropic plasticity criterion. The resulting constitutive equations are implementedand assessed for the prediction of fracture onset in sheet metal forming processes. Anexperimental failure case is presented to demonstrate the applicability of the implementedmodel in the necking prediction in sheet metal forming processes. Corresponding numericalsimulation is performed and its results compared with experimental ones for a selectedmaterial.
Subject: Engenharia mecânica, Engenharia mecânica
Mechanical engineering, Mechanical engineering
Scientific areas: Ciências da engenharia e tecnologias::Engenharia mecânica
Engineering and technology::Mechanical engineering
Source: IDDRG 2008 - International Deep Drawing Research Group Conference
Document Type: Artigo em Livro de Atas de Conferência Internacional
Rights: restrictedAccess
Appears in Collections:FEUP - Artigo em Livro de Atas de Conferência Internacional

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