-
摘要: 用分子动力学方法模拟计算了在初始温度为0 K时单晶铜中的冲击波结构,相互作用势采用铜的嵌入原子势(EAM),模拟计算结果表明即使是在初始温度为0 K的FCC晶体中,冲击波波阵面后的区域也会向平衡态演化。局域分析表明冲击波阵面后区域的压力、粒子速度、应变和温度随时间逐步变化到稳定态,在所研究的冲击波强度(约262 GPa)下,波后区域的平均压力、粒子速度、应变均在约1 ps内逐渐上升并达到稳定值。动能温度在波阵面处始终为最大值,随着冲击波的传播,波后非零温度区域逐渐扩大,不同时刻的粒子速度分布函数说明波后区域逐渐向热力学平衡态演化,并最终达到热力学平衡,进一步的分析说明局域平衡是系统向平衡态演化的基本过程。Abstract: The structure of shock wave in single crystal copper has been studied by means of molecular dynamics (MD) method with a realistic embedded atom potential at initial condition of zero temperature. The simulation results indicate that the after-shock state will evolve to thermodynamic equilibrium state even initial state is zero temperature. By means of local analysis and calculation, time history of the distribution of pressure, particle velocity, strain and kinetic temperature after the shock front were obtained. The pressure, particle velocity, and strain increase and arrive at the stable condition within time period about 1 ps when shock pressure is about 262 GPa. The kinetic temperature always keeps maximum value in shock wave front and the nonzero temperature region broadens behind the shock wave as time passes by. After evolution of a critical time, the particle velocity in the after-shock region reaches a typical Maxwell distribution which means it reaches equilibrium state. The further analysis indicates that local equilibrium is an elemental course when the whole system evolves to thermodynamic equilibrium state.
-
Key words:
- shock wave /
- molecular dynamic /
- equilibrium state
-
Tsai D H, Beckett C W. Shock Wave Propogration in Cubic Lattices [J]. J Geophys Res, 1966, 71: 2601-2608. Zhakhovskii V V, Zybin S V, Nishihara K, et al. Shock Wave Structure in Lennard-Jones Crystal via Molecular Dynamics [J]. Phys Rev Lett, 1999, 83: 1175-1178. Tsai D H, MacDonald R A. Second Sound in a Solid under Shock Compression [J]. J Phys C: Solid St Phys, 1973, 6: L171-175. Tsai D H, MacDonald R A. Molecular-Dynamical Study of Second Sound in a Solid Excited by a Strong Heat Pulse [J]. Phys Rev B, 1976, 14: 4716-4723. Paskin, Gohar A, Dienes G J. Simulations of Shock Waves in Solids [J]. J Phys, 1977, 10: L563-L566. Manvi R, Duvall G E, Lowell S C. Finite Amplitude Longitudinal Waves in Lattices [J]. Int J Mech, 1969, 11: 1-8. Straub G K, Holian B L, Petschek R G. Molecular Dynamics of Shock Wave in One-Dimensional Chains(Ⅱ): Thermalication [J]. Phys Rev B, 1978, 19: 4049-4055. Timothy C, Germann, Holian B L. Plastic Deformation in Shock Waves via Molecular-Dynamics Simulations [A]. //Furnish M D, Chhabildas L C, Hixson R S. Shock Compression of Condensed Matter-1999 [C]. New York: American Institute of Physics, 2000: 297-300. Holian B L, Straub G K. Molecular Dynamics of Shock Wave in Three-Dimensional Solids: Transition from Nonsteady to Steady Waves in Perfect Crystals and Implications for the Rankine-Hugoniot Conditions [J]. Phys Rev Lett, 1979, 43: 1598-1600. Holian B L, Hoover W G, Moran B, et al. Shock-Wave Structure via Nonequilibrium Molecular Dynamics and Navier-Stokes Continum Mechanics [J]. Phys Rev A, 1980, 22: 2798-2808. Holian B L. Modeling Shock-Wave Deformation via Molecular Dynamics [J]. Phys Rev A, 1987, 37: 2562-2568. Norman J, Wagner, Holian B L. Molecular-Dynamics Simulation of Two-Dimensional Materials at High Strain Rates [J]. Phys Rev A, 1992, 45: 8457-8469. Pan Y S. Molecular Dynamics Study of High Pressure Shock Compression of Solids [D]. Mianyang: China Academy of Engineering Physics, 1997: 1-37. (in Chinese) 潘原生. 固体高压冲击压缩的分子动力学研究 [D]. 绵阳: 中国工程物理研究院, 1997: 1-37. Mishin Y, Mehl M J, Papaconstantopoulos D A. Structural Stability and Lattice Defects in Copper: Ab initial, Tight-Binding, and Embedded-Atom Caculations [J]. Phys Rev B, 2001, 63: 224106-1-15. Luo J, Zhu W J, Lin L B, et al. Molecular Dynamics Simulation of Void Growth in Single Crystal Copper under Uniaxial Impacting [J]. Acta Physica Sinica, 2005, 54(6): 2791-2798. (in Chinese) 罗晋, 祝文军, 林理彬, 等. 单晶铜在动态加载下空洞增长的分子动力学研究 [J]. 物理学报, 2005, 54(6): 2791-2798. Cormier J, Rickman J M, Delph D J. Stress Calculation in Atomistic Simulations of Perfect and Imperfect Solids [J]. J Appl Phys, 2001, 89: 99-104. Seppala E T, Beleak J, Rudd R E. Effect of Stress Triaxiality on Void Growth in Dynamic Fracture of Metals: A Molecular Dynamics Study [J]. Phys Rev B, 2004, 69: 134101-1-19. Zybin S V, Elert M L, White C T. Molecular Dynamics Study of Non-Reacting Shock Waves in Anthracene [A]. //Furnish M D, Gupta Y M, Forbes J W. Shock Compression of Condensed Matter-2003 [C]. New York: American Institute of Physics, 2004: 306-309. Hayes D, Hixson R S, McQueen R G. High Pressure Elastic Properties, Solid-Liquid Phase Boundary and Liquid Equation of State from Release Wave Measurements in Shock-Loaded Copper [A]. //Furnish M D, Chhabildas L C, Hixson R S. Shock Compression of Condensed Matter-1999 [C]. New York: American Institute of Physics, 2000: 483-488. Bringa E M, Cazamias J U, Erhart P, et al. Atomistic Shock Hugoniot Simulation of Single-Crystal Copper [J]. J Appl Phys, 2004, 96: 3793-3799.
点击查看大图
计量
- 文章访问数: 7483
- HTML全文浏览量: 260
- PDF下载量: 796