NUMERICAL STUDY OF THE RELATIONSHIP BETWEEN THE CRYSTAL YIELD STRESS AND HARDENING WITH THE DENSITY OF DISLOCATION SOURCES AND OBSTACLES, USING A DISCRETE DISLOCATION MODEL

FEDERICO LANGHI; ALFREDO HUESPE; PABLO SANCHEZ

São Paulo

Congreso; 10th WORLD CONGRESS ON COMPUTATIONAL MECHANICS (WCCM 2012); 2012

It is well known that conventional plasticity models do not capture,at microscopic scales, the influence of physically-based important phenomena during plastic deformation. Some of these effects are associated with specific parameters that are related with physical characteristic lengths of the problem at hand. Typically this happens with the crystal grain sizes and the role that this parameter has on the yield stress, hardening mechanism, etc. In this paper, using a numerical discrete dislocation model (Deshpande et al. (2005), Cleveringa et al. (2000)), a study of the effects that the density of dislocation sources and obstacles have on the conventional plastic parameters is presented. The analysis is performed at scales of length that are in the order of the grain size O(10m)). Specifically, a mono-crystal is analyzed. Two parameters of the numerical model are studied. Both of them affect the yield stress and the hardening. One is the grain size, and the other is the concentration of solute in the crystal, characterized in this case by the variation of the obstacles density interfering the dislocation movement (Strengthening mechanisms in crystal plasticity (2008)).