| Co-Investigator(Kenkyū-buntansha) |
ODA Kenji Hokkaido University, Faculty of Engineering, Instructor, 工学部, 助手 (40002208)
SASAKI Kazuaki Hokkaido University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (10153983)
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| Budget Amount *help |
¥7,100,000 (Direct Cost: ¥7,100,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1992: ¥6,000,000 (Direct Cost: ¥6,000,000)
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| Research Abstract |
The local mechanical behavior of polycrystalline solid is affected by the grain size, the grain direction and the state of grain boundary. The aim of this research is the elucidation of mechanical behavior of polycrystalline solid by comparing the results of numerical simulations and actual experiments. At first, each grain is modeled by the regular hexagon, and the mechanical simulation of tensile problem is carried out by the well-known finite element method. From the results, it is shown that the structure may be considered as the macro-continuum solid, if there exist 15 grains toward tensile axis and 8 grains toward vertical axis. Also, the stress and the strain in each grain are obtained. When the differences of the material constant, such as modulus of elasticity, between each neighboring grains are large, there exist large stresses near the grain boundary, especially, in the grain with large modulus of elasticity. It is shown that the iso-stress lines exist in polycrystalline so
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lid, which represent the macro deformation behavior, such as slip, qualitatively.
Next, the polycrystalline tensile test specimen is made by Aluminum plate (Akebono Brake Co., Ltd, Grain de Reve) used for wall materials of an architecture and having the coarse crystal grains. The test specimen, which has the grain boundary perpendicular to tensile axis, is polished up like a mirror surface, and the linear model grids (250 lines/inch) are printed out on the surface of test specimen. The specimen is subjected to tensile load, and the scanning Moire image photo are taken by the high vision CCD camera every 1% strain. The strains near the grain boundary are obtained from these Moire images by the use of high vision image processor. From the results, it is shown that the strain distribution varies before and after grain boundary. In actual measurement, when the gauge strain is 5%, the strain before/after grain boundary is about 2%/20%. Because of the difference of mechanical properties between neighboring grains, the mechanical behavior in neighboring crystal grain varies discontinuously at grain boundary. This fact is coincide with the results of numerical simulation. Less
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