二维晶格中激波的传播和自由面反射的分子动力学数值研究

本文用分子动力学方法研究和计算了面心晶体中沿(1、0、0)面或休心晶体中沿(1、1、0)面上激波的传播和自由面反射现象。在所研完的范围内(u_p=10~75×10⁴cm/sec)粒子速度沿平均值的振动是不衰减的,激皮的传播速度和波后粒子速度的平均值呈线性关系。激波在自由面反射后,自由表面附近的粒子速度为活塞速度的二倍,这和宏观力学结果相同。此外,还出现最外层分子不断地以更高的速度被抛离的现象,这和宏观测量的微物质喷射现象亦类似。在稍后的阶段,还显示出内部粒子间被拉开的"微断裂"现象。

THE MOLECULAR DYNAMICAL SIMULATION OF SHOCK WAVE PROPAGATION AND REFLECTION FROM FREE SURFACE IN TWO-DIMENSIONAL LATTICE

The propagation of shock wave and it's reflection at free surface in two-dimensional lattice are considered and calculated by method of molecular dynamics. This lattice simulates the (1,0,0) plane for face centered cubic (f.c.c) or the (1,1,0)plane for body centered cubic(b.c.c).In the range of our calculation (u_p=10-75×10⁴cm/sec), the oscillation of particle velocity is'nt decrescent. The shock wave velocity is a linear function of average particle velocity. After reflection, the average particle velocity near free surface is equal to twice the piston velocity approximately, which agrees with macroscopic phenomena. The particles at outer-most layer of free surface, get the large value of velocity and go away from this surface. It is also similar to the macroscopic phenomena of ejection. At the later stage of expansion, the particles in the interial region may lose connection between them, that corresponds to the microscopic fracture.