Papers by Author: Jian Guo Tang

Abstract: The particle swarm optimization (PSO) algorithm is introduced into ghost correction, which is also compared with the NMS algorithm. With linear regression correlation factor as evaluation parameter, it is found that both algorithms have the same quality for model ODF, but when it comes to complicated textures, the PSO algorithm shows high ODF fitting quality. It is also demonstrates that the ghost peaks in the reduced ODF can be excluded out in the true ODF from PSO components with both even and odd terms in the series expansion method.

Abstract: Void growth in aluminum single crystals is simulated using the finite element method, to illustrate the effect of grain orientation on void growth, a rate dependent crystal plasticity constitutive theory is implemented as a user-defined plasticity subroutine. A three-dimension unit cell including a sphere void was employed using three-dimensional 12 active slip systems. The computed results for several grain orientations are compared, which have shown that crystallographic orientation has significant influence on growth behavior of void. And the void growth direction and shape significantly depend on the crystallographic orientation. Due to plastic flow localization and anisotropic behavior, void which has an initial sphere shape, develops an irregular shape and some corners.

Abstract: The influence of crystallographic orientation stability on the inhomogeneous deformation on the meso-scale was numerically simulated with the crystal plasticity finite element. The initial microstructures were introduced into the finite element via intra-granular orientation gradient. The results demonstrated that the average orientation for both stable Goss and meta-stable cube oriented grains changed very little in plane strain compression (PSC). And for stable Goss oriented grain, the orientation gradient increased slightly, but for meta-stable cube oriented grain, the orientation gradient increased dramatically. And in spite of the same Taylor factor for both oriented grains, the dissipated averaged energy for cube oriented grain was higher than for Goss oriented grains, and the distribution width of dissipated work in cube oriented grain was also wider than that in Goss oriented grain. Furthermore, there was also strong energy gradient in PSC of cube oriented grain. Both the orientation gradient and energy gradient favor the nucleation of cube grains during recrystallization.