The Initiation And Growth Simulation Of Single Crystal Metal Micro-crack Based On Molecular Dynamics

With the advent of nano-technology, people's attention gradually shifted from the macro objects to the corresponding small-scale devices, as research continues to deepen, there is an urgent need to understand nano-scale materials crack initiation and growth of microscopic mechanism, experiment with the theory, there are varying degrees of difficulty, and molecular dynamics simulation technology precisely such problems can be solved.When forming the model in order to reduce the number of particles as small imbalance between the traditional the model was improved; Potential function use dual potential of Lennard-Jones potential function and Morse potential function; Molecular dynamics of the various algorithms stability compared using Verlet algorithm equation of motion to solve; using the Maxwell-Boltzmann distribution to determine the atomic initial velocity; Temperature control system use direct calibration method to speed the pace calibration; Contrast units used to improve computational speed, use the freezing atom method to dispose the atomic speed, Verlet list to calculate ensemble energy and atomic force, in order to improve computational speed. Use the Visual Basic 6.0 senior language, and use object-oriented technology program to design program, developed a single crystal metal micro-cracks simulation software. The software can be completed FCC single crystal metal micro-crack initiation and growth of the simulation.Use the software development to simulate the single crystal copper micro-cracks, edge crack plate tensile and bending be simulated, first the simulation model relax for some time to eliminate the surface effect of atomic, with the loading steps increasing, some atoms of the model aberrance from ideal location of the atomic lattice, the simulation process observed that the process began to form crack tip passivation, then, there was vacancy forming, when the vacancy increasing and slip to a certain degree that it is becoming instability then the crack began to propagate; The center crack plate tensile simulation also be simulated, the simulation process can be clearly observed that the passivation, next the vacancy was forming, crack tip instability expansion, initiation and growth process and the plate cracks is similar to the right side plate crack; energy and stress variables be tracked and analyzed, then plot its time curve.Simulation results show that the software developed by the design and the design method is feasible and correct. As long as the software changes the corresponding parameters can be right on the other FCC single crystal metal micro-crack initiation and growth simulation.