Article: Damage mechanics approach in crack growth simulation during the fine blanking process Journal: International Journal of Materials and Product Technology (IJMPT) 2003 Vol.19 No.6 pp.466 - 478 Abstract: This paper describes a finite element model (FEM) valid for numerical simulation of sheet-metal fine blanking processes. The numerical simulation of the damage evolution and crack initiation and propagation have been described by means of continuum damage approach. The main difficulty encountered in simulating this operation is describing the behaviour of the sheet continuously from the beginning of the operation up to the total rupture. In this case, choosing a behaviour law is crucial, since each successive step in the whole process has to be described accurately. In this work, an elastoplastic behaviour law coupled with damage has been retained to describe the progressive damage accumulation in the workpieces. Starting from Lemaitre damage model and based on the Rice and Tracey ductile fracture criterion, a new pressure-dependent damage model has been developed allowing for the description of the exponential dependence on triaxiality stress field. During the analysis, the initiation of crack is supposed to occur at any point in the structure where the damage reaches its critical value Dc. The crack propagation is simulated by the propagation of a completely damaged area. This is taken into account in the FEM by decrease in the stiffness of the broken elements. The comparative study between the results obtained by the simulations using the proposed model and the experimental ones, showed that it is possible to predict the crack propagation into the sheet path in a realistic way. Inderscience Publishers - linking academia, business and industry through research

Title: Damage mechanics approach in crack growth simulation during the fine blanking process

Authors: R. Hambli, S. Richir

Addresses: Istia-Lasquo, 62, Avenue Notre Dame du Lac, 49000 Angers, France. Istia CPNI, 62, Avenue Notre Dame du Lac, 49000 Angers, France

Abstract: This paper describes a finite element model (FEM) valid for numerical simulation of sheet-metal fine blanking processes. The numerical simulation of the damage evolution and crack initiation and propagation have been described by means of continuum damage approach. The main difficulty encountered in simulating this operation is describing the behaviour of the sheet continuously from the beginning of the operation up to the total rupture. In this case, choosing a behaviour law is crucial, since each successive step in the whole process has to be described accurately. In this work, an elastoplastic behaviour law coupled with damage has been retained to describe the progressive damage accumulation in the workpieces. Starting from Lemaitre damage model and based on the Rice and Tracey ductile fracture criterion, a new pressure-dependent damage model has been developed allowing for the description of the exponential dependence on triaxiality stress field. During the analysis, the initiation of crack is supposed to occur at any point in the structure where the damage reaches its critical value Dc. The crack propagation is simulated by the propagation of a completely damaged area. This is taken into account in the FEM by decrease in the stiffness of the broken elements. The comparative study between the results obtained by the simulations using the proposed model and the experimental ones, showed that it is possible to predict the crack propagation into the sheet path in a realistic way.

Keywords: crack growth; damage law; experiment; fine blanking; finite element.

DOI: 10.1504/IJMPT.2003.003465

International Journal of Materials and Product Technology, 2003 Vol.19 No.6, pp.466 - 478

Published online: 10 Sep 2003 *

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Title: Damage mechanics approach in crack growth simulation during the fine blanking process

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