| Current researches show that twin crystal boundary has an important influence on transformation of nanometer materials and can further effect the mechanical properties of nanometer materials. This paper uses the embedded-atom method (EAM) potential function developed by Johnson and Nose-Hoover method, and studies mechanical properties of twinned crystal Au nanomodel by molecular dynamics simulations.In the process of researching mechanical properties of 1D twinned crystal Au nanowires, this paper constructs the twinned models, which is under the load parallel to twin boundary direction. The results of the stretched simulation for twinned Au nanowires show that the deformation mechanism of the nanowires are similar, and both the low coordination atom amorphous movement and slip surface affect the fracture of the nanowires. It is found that the Young's modulus of nanowires compressed is 2 times as large as nano wires stretched.When the length of nanowires increases, the Young's modulus has a decreasing trend, and the average potential energy also decreases. It is also found that the tensile rate has few effect on the yielding status of nanowires. With the tensile rate increasing, the average potential energy increases.For 3D twinned crystal Au nanostructer, this paper uses microscopic mechanics formula, combining with the theory of molecular dynamics to study the mechanical properties of 3D twinned crystal Au nanostructer. The mechanical properties of 3D twinned Au nanostructer is studied, by setting different tensile rate. The results of the simulation show that the deformation mechanism for 3D nanostructer is different from the 1D model: for the 3D model, only the low coordination atom amorphous movement affects the fracture of the model. As the tensile rate increases, the Young's modulus decreases, while the Mises stress is almost unchanging. Under three direction loads, the average potential energy increases suddenly and its increasing range is big with tensile rate increasing. |
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