| Autor: |
Dell, Harry, Gese, Helmut, Oberhofer, Gernot |
| Předmět: |
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| Zdroj: |
AIP Conference Proceedings; 2007, Vol. 908 Issue 1, p165-170, 6p, 1 Diagram, 1 Chart, 1 Graph |
| Abstrakt: |
A correct prediction of a possible sheet metal failure is essential to sheet metal forming simulations. The use of the conventional forming limit curve (FLC) is the standard approach on industrial level for this problem. The FLC concept is limited to the case of linear strain paths, however. The initial FLC is no longer valid in the case of nonlinear strain paths. The algorithm Crach allows for a transient prediction of the forming limit for localized necking in the case of arbitrary strain paths. For high strength steels and aluminium sheets there is also a risk of fracture without prior localized necking. This paper presents a fracture model that accounts for ductile fracture (caused by void nucleation, void growth and void coalescence) and shear fracture (caused by shear band localization). For both types of fracture, stress state parameters are introduced which can be applied for the plane stress state and for the general 3D stress state. The fracture limits are defined by the equivalent plastic strain at fracture as a function of the stress state parameter based on different experiments with nearly constant stress state parameter. These fracture limit curves are a basis for an integral damage accumulation in the sheet metal forming simulation for arbitrary nonlinear strain paths. The model Crach for the prediction of localized necking and the two fracture models for ductile and shear fracture are combined in the comprehensive failure model CrachFEM. CrachFEM can be linked via a user material model MF GenYld to different explicit FEM codes. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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