| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 95 === In recent years, there has been much advancement in the field of science and technology. As a result, many nanostructures have been manufactured. However, current measurement systems are still not accurate enough to describe the physical behavior of these nanostructures. Scholars thus developed a renewed interest in the field of potential function in describing the diatom interaction.
In light of this, the current study uses finite element methods (FEM) and the atomistic-continuum mechanics method (ACM) to explore Young’s modulus, and the size effect of nanostructures. This method could examine the nanostructures’ mechanical properties with high efficiency and accuracy. The diatom binding energy is described by the Morse potential function. Meanwhile, the interatomic force and the position of atoms are replaced by an equivalent spring element and nodes, respectively. The size effect of the nanostructure will affect the atoms’ mechanical properties.
The copper element is used as the test vehicle in this research. A comparison of different crystallography planes of (100), (110), and (111) on Young’s modulus is presented. The results show that different crystallography planes have different material properties which agree with the results of other studies.
Both analytical and numerical solutions are adopted in this research. The numerical model conducted by ANSYS software analysis obtained the reaction forces and natural frequency of the nanostructures in order to examine their mechanical properties. The results of both
tensile and modal analysis are found to be reliable and acceptable.
On the other hand, this research also investigates the point defect’s distribution under tensile testing and modal analysis. The results reveal that the point defect distribution will affect the structure’s mechanical properties especially when the vacancy defect distribution concentrates at the free side of the specimen. The slip planes in the greatest planar density are also observed when the specimen with defects undergoes tensile testing.
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