Prediction on Nominal Stress-Strain Curve of Anisotropic Polycrystal with Texture by FE Analysis

Abstract

In order to predict nominal stress-strain (S-S) curve in tensile test for a commercial purity titanium (hereafter, CP-Ti) with texture, three boundary conditions are elucidated as well as plastic anisotropy in three-dimensional finite element (FE) analysis. Three boundary conditions are a free case, a full constraint case at both ends of specimen, and a simulated case based on empirical data. In the simulated case, the shape change and the nominal S-S curve can be well predicted with deviation smaller than 10%. The origin of localized necking is concluded not due to the plastic instability but due to the constraint at both ends of specimen. Deviation point of the nominal S-S curve at the simulated case from that of the free case has been suggested as the onset of localized necking of CP-Ti, which is determined as 0.25 in transverse direction and 0.50 in rolling direction.

Prediction of Nominal Stress-Strain Curves of a Multi-Layered Composite Material by FE Analysis

“…2. 12,13) The microstructure of as-annealed CP-Ti is composed of equiaxed grains and (0001) crystal planes parallel to normal direction (ND) section as shown in Fig. 2(a).…”

“…Thus, the anisotropic plasticity of CP-Ti can be assumed in the FE analysis. 13) Figure 2(b) shows the microstructure and IPF (ND section) of as-annealed Ti-15-3 alloy. The IPF reveals that there is no obvious texture and an isotropic deformation can therefore be assumed in the FE analysis.…”

“…14) The true S-S relation ¼ 848:2" 0:03 (R 2 ¼ 0:958) has been successfully used to predict the nominal S-S curve of as-annealed Ti-15-3 alloy, 12) and ¼ 382:0ð" þ 0:004Þ 0:10 (R 2 ¼ 0:996) for asannealed CP-Ti in transverse direction (TD).…”

“…The IPF reveals that there is no obvious texture and an isotropic deformation can therefore be assumed in the FE analysis. 13) Figure 3(a) and (b) respectively shows the EBSD microstructure and the IPF of components in multi-layered composite (HRB9-A1C1). The distribution of alloy elements across the interface was plotted as line scans using EDS as shown in Fig.…”

“…12,13) In the present work, the nominal S-S curves of as-rolled and as-aged multi-layered composite, which is hot-rolled by bonding an anisotropic CP-Ti and an isotropic Ti-15-3 component, are predicted by FE analysis. Discussions were also made on the effect of aging treatment on the nominal S-S curves of the multi-layered composites.…”