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Simulation of Defects on the Interface Based on Molecular Dynamics

Author: RenDongWei
Tutor: XuJinQuan
School: Shanghai Jiaotong University
Course: Solid Mechanics
Keywords: Molecular Dynamics Interface Defect Potential First-Principle
CLC: TB303
Type: Master's thesis
Year: 2011
Downloads: 123
Quote: 0
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Abstract


With the widespread application of various kinds of composite materials and functional materials, interface is almost everywhere in both macrograph and micrograph, people pay more attention to the mechanical behavior of bi-material. Fracture of bi-material often occurs at or near the interface, because there are not only varieties of defects at or near the interface which weaken the interface strength, but also stress singularity of interface edge and oscillatory stress singularity of interface crack tip leading to a higher stress level on the interface. So the strength and working life of structures composed by bi-material depend on the strength and working life of interface, and defects play an important role in this process. Nowadays the emphases of research focus on explaining the mechanical behavior of macro interface in micrograph degree.With the rapidly development of computer technology, molecular dynamics (MD) has become a widely used method of molecular simulation. Molecular dynamics is an integrated technology combined by physics, mathematic and chemic. Its main purpose is to simulate the motion of atomic system by Newton’s principle, pick up sample from different states in order to calculate the configuration integration of the system, and then get other system’s macro features with the configuration integration.But how defects come into being on the interface isn’t very clear at present. In the paper, we simulated the interfacial molecular structure with different lattice constants by the method of molecular dynamics (MD). Potential of modified analytical embedded atom method (MAEAM) is used for non-interfacial atoms. To simulate the interfacial atom’s state, further modifications are applied to the MAEAM potential through the comparison with the results based on the first-principle simulations. It is found that a small change of potential may influence the interfacial molecular structure greatly. Void and diffusions can be observed in the simulation results. It is also found that the pre-existed dot defects before bonding can decrease the interfacial defects greatly, thereby, can improve the strength of the interface.

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CLC: > Industrial Technology > General industrial technology > Materials science and engineering > General issues of engineering materials > Material structure and physical properties
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