Molecular Dynamics Simulation Of Strength Of Single Crystal Cu Under Different Pressure

As the fundamental quantity of the precise equation of state and constitutive equation under high pressure, the strength of materials under high pressure is very important in the design of weapon and spacecraft. The study of the strength of materials is a multiple scale problem. To understand the deformation behavior and pre-estimate the strength accurately, researches on different length scale are needed, since the strength of material is.In this work, the strength of single crystal Cu under different pressure is investigated by means of Molecular Dynamics simulation. The pure shear model is been applied in this work, which can provide the direct description of plastic deformation behavior, since the plastic deformation is activated by deviatonic stress (resolved shear stress). The variant pressures are obtained through changing of the lattice constant of Cu crystal.The elastic constants of crystal Cu were tested and verified before the formal dynamic shear simulation to make sure the analog result is correct. The elastic constants calculated are in conformity to experimental results of crystal Cu, which indicate applicability of the applied potential function, the simulation program used and the model constructed.Through the help of the simulation, the deformation behaviors of the single crystal Cu under shear loading are represented, the differences between the results under different shear velocities loading are analyzed. The propagation velocities of shear stress and hydrostatic pressure are obtained by analyzing the changes of them depending on the time.The relation between the strength of single crystal Cu and pressure is obtained. The simulation results with different pressure indicate that the peak shear stress of the single crystal increase with the increase of the pressure, and the same is found when it comes to the shear stress and hydrostatic pressure propagation velocity. The increase ratio of the strength and stress propagation velocity under tension pressure is greater than that under compression pressure.The stress-strain curves of the single crystal Cu shearing along {111} plane are represented. The shear modulus obtained from the stress-strain curves are in good agreement with those calculated with shear stress propagation velocities and densities of the crystal. It means that the results of the shear simulations under different pressure are reliable when relating to the theory of linear perturbation.