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Recherche - Valorisation

Thermo-viscoplastic Instability and Multiple Adiabatic Shear Banding in Metallic Materials

le 12 juin 2014
13H30

Fenghua ZHOU, Professor of The faculty of mechanical engineering and mechanics, Ningbo university, 315211, China

Thermo-viscoplastic instability is the mechanism leading to adiabatic shear localization and shear banding. In this paper, we studied the formations of one single or multiple adiabatic shear bands in a slab under one-dimensional shear. The conventional Johnson-Cook thermo-viscoplastic constitutive model was used to describe the dynamic plastic behavior of the material. The numerical methodology that uses finite difference scheme along the characteristic lines was applied to investigate the development of shear deformation in a slab, including the homogeneous plastic flow, the plastic flow instability, and the shear localizations. For the case of single band formation, the influences of initial temperature disturbances or geometry defects were studied. For the case of multiple band formation, the average shear band spacings are found to be dependent on the prescribed strainrate and the characteristic distributions of initial disturbances. If the initial disturbances were space distributed randomly, the average spacing between multiple shear bands agrees with the Grady-Kipp formula. The investigations confirmed that the periodic distributed defects in the slab affect the formation of multiple shear bands. Under certain strainrate region, the formation of multiple shear bands was completely controlled by the periodic defects.
Type :
Séminaires - conférences
Lieu(x) :
Campus de Cachan
Amphi e-média
Bâtiment Léonard De Vinci de - ENS Cachan
61, avenue du Président Wilson 94230 Cachan
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