کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
797469 | 1467157 | 2007 | 20 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Higher-order stress and grain size effects due to self-energy of geometrically necessary dislocations Higher-order stress and grain size effects due to self-energy of geometrically necessary dislocations](/preview/png/797469.png)
The higher-order stress work-conjugate to slip gradient in single crystals at small strains is derived based on the self-energy of geometrically necessary dislocations (GNDs). It is shown that this higher-order stress changes stepwise as a function of in-plane slip gradient and therefore significantly influences the onset of initial yielding in polycrystals. The higher-order stress based on the self-energy of GNDs is then incorporated into the strain gradient plasticity theory of Gurtin [2002. A gradient theory of single-crystal viscoplasticity that accounts for geometrically necessary dislocations. J. Mech. Phys. Solids 50, 5–32] and applied to single-slip-oriented 2D and 3D model crystal grains of size D . It is thus found that the self-energy of GNDs gives a D-1D-1-dependent term for the averaged resolved shear stress in such a model grain under yielding. Using published experimental data for several polycrystalline metals, it is demonstrated that the D-1D-1-dependent term successfully explains the grain size dependence of initial yield stress and the dislocation cell size dependence of flow stress in the submicron to several-micron range of grain and cell sizes.
Journal: Journal of the Mechanics and Physics of Solids - Volume 55, Issue 9, September 2007, Pages 1879–1898