Effect of crystal orientation on porosity evolution in a creeping single crystal
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© 2015 Elsevier Ltd. All rights reserved. The effect of crystal orientation on porosity evolution in a face centered cubic (fcc) single crystal subject to tensile creep loading is analyzed. The matrix material is characterized by a rate power law viscous crystal plasticity constitutive relation. Three dimensional finite deformation finite element analyses of initially cubic unit cells containing a single initially spherical void are carried out for three crystal orientations of the main loading direction together with two other cases analyzed to study the effect of secondary orientations. The calculations are carried out for three values of the stress triaxiality and for each stress triaxiality value three values of the Lode parameter are considered. Two of the crystal orientations are significantly anisotropic orientations. Symmetry boundary conditions are imposed consistent with the crystal symmetry; the sides of the unit cell are not constrained to remain straight. For an anisotropic orientation, the Lode parameter can have a significant effect on the evolution of creep strain and porosity even at relatively high values of the stress triaxiality. An overall enhanced creep rate can occur with no void growth or even accompanying void collapse. Also, whether or not a stress concentration greater than the elastic stress concentration develops depends on crystal orientation.
author list (cited authors)
Srivastava, A., & Needleman, A.