Gumbsch P, Gao H
Max-Planck-Institut fur Metallforschung, Seestrasse 92, 70174 Stuttgart, Germany. Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.
Science. 1999 Feb 12;283(5404):965-8. doi: 10.1126/science.283.5404.965.
It is thought that dislocations cannot surpass the sound barrier at the shear wave velocity because the energy spent in radiation has a singularity there. Atomistic simulations show that dislocations can move faster than the speed of sound if they are created as supersonic dislocations at a strong stress concentration and are subjected to high shear stresses. This behavior is important for the understanding of low-temperature deformation processes such as mechanical twinning and may be relevant for the dynamics of tectonic faults. The motion of the dislocations at a speed of 2 times the shear wave velocity can be understood from a linear elastic analysis, but many of the peculiarities of the supersonic dislocations are dominated by nonlinear effects that require a realistic atomistic description.
人们认为位错无法以剪切波速度超越声障，因为在辐射中消耗的能量在那里具有奇异性。原子模拟表明，如果位错在强应力集中处作为超音速位错产生并受到高剪切应力作用，它们可以比声速移动得更快。这种行为对于理解诸如机械孪生等低温变形过程很重要，并且可能与构造断层的动力学有关。从线性弹性分析可以理解位错以两倍剪切波速度的运动，但超音速位错的许多特性由需要实际原子描述的非线性效应主导。
