冲击作用下金属表面微喷射的分子动力学模拟

Molecular dynamics simulation of micro particle ejection from a shock-impacted metal surface

利用二维分子动力学程序 ,结合类紧束缚杂化多体势 ,研究冲击载荷下金属表面包含沟槽型缺陷的微喷射动力学过程 .在产生微喷射以后 ,结果表明材料内部传播着两种波系 :反射稀疏波和二次加载压缩波 ,其中 ,反射稀疏波波面与沟槽形状相似 ,而二次压缩波波面随沟槽夹角的变化而变化 ;并形成了两个压强区 :负压区和正压区 ,负压区的存在表明材料中可能产生微损伤 .同时 ,统计结果表明微喷射体的速度随沟槽半角增加而增加的趋势 ,微喷射体的粒子数随沟槽半角增大而减少的趋势 ,当沟槽半角大于 6 0° ,微喷射效应消失 .

The dynamic process of micro particle ejection from shock impacted metal with grooved surface is investigated by molecular dynamics simulation using a hybrid tight binding like potential. The calculated results show that, after ejection, there propagate in sequence a reflection rarefaction wave and a second uploading compression wave in the material, and correspondingly a negative pressure region and a high pressure region are induced. The front shape of the reflection rarefaction wave is similar to the groove shape, but the front shape of the second uploading compression wave varies with the groove angle. The average velocity of the ejected particles increases with the groove angle. On the contrary, the amount of ejected particles decreases as groove angle increases. When the groove semi angle is larger than 60 degrees, ejection disappears.