hal-02279852
https://utt.hal.science/hal-02279852
[CNRS] CNRS - Centre national de la recherche scientifique
[URCA] Publications de l'Université de Reims Champagne-Ardenne
[UNIV-TROYES] Université de Technologie de Troyes
[UTT] UTT
Numerical simulation of burst defects in cold extrusion process
Labergere, Carl
Lestriez, Philippe
Saanouni, Khemais
[SPI.MECA.MEMA] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph]
COMM
The formation of the central bursts in axisymmetric cold extrusion is numerically simulated by using 2D finite element analysis (FEA) accounting for the mixed isotropic and kinematic hardening together with the ductile damage effect. The coupling between the ductile damage and the elastoplastic constitutive equations is formulated in the framework of the thermodynamics of irreversible processes together with the Continuum Damage Mechanics (CDM) theory. An isotropic ductile damage model is fully coupled with elastoplastic constitutive equations including non linear isotropic and kinematic hardening. A modified ductile damage criterion based on linear combination of the stress tensor invariants is used in order to predict the occurrence of micro‐crack initiation as a discontinuous central bursts along the bar axis. The implicit integration scheme of the fully coupled constitutive equations and the Dynamic Explicit resolution scheme to solve the associated initial and boundary value problem are outlined. Application is made to the prediction of the chevron shaped cracks in cold extrusion of a round bar. The effect of various process parameters, as the diameter reduction ratio, the die semi‐angle, the friction coefficient and the material ductility, on the central bursts occurrence are discussed.
2007-06-17
en
AIP
MATERIALS PROCESSING AND DESIGN; Modeling, Simulation and Applications; NUMIFORM '07; Proceedings of the 9th International Conference on Numerical Methods in Industrial Forming Processes
Porto, Portugal