【作者】 李宝宝；

【导师】 汤文辉；

【作者基本信息】 国防科学技术大学 ， 力学， 2010， 硕士

【摘要】 在超高速碰撞中,碰撞产生的冲击压力远大于材料的强度。在碰撞点附近的区域内,材料的行为响应特点类似于可压缩流体。对超高速碰撞而言,材料的可压缩效应甚至相变效应会在其中扮演重要的角色。为了探讨在超高速碰撞中相变的影响,本文在自编SPH程序中引入GRAY三相物态方程,对超高速碰撞问题进行数值模拟研究,并与常用的Tillotson物态方程进行对比分析,探讨了超高速碰撞中相变效应产生的影响。得到如下结果:1、在较低的碰撞速度(不发生相变)下,GRAY三相物态方程计算所得的碎片云形状参数与Tillotson物态方程给出的结果吻合,表明GRAY三相物态方程适于应用于超高速碰撞的数值模拟。2、对碎片云的形状、质量、速度和动量特性进行了数值研究,结果表明,在较高速度下,两个物态方程给出的结果有一些差别,分析表明,这些差异是由于超高速碰撞中相变效应引起的。3、在较高碰撞速度(8 km/s)下,给出了碰撞初期某些时刻的物理量分布情况,得到超高速碰撞熔化、汽化相变发生的区域,同时还获得了喷射尾罩产生的区域。4、探讨了Whipple防护结构的防护性能问题。分析表明,材料的相变效应和热软化效应对于防护结构的防护性能影响较大。更多还原

【Abstract】 During hypervelocity impacting, the shock pressure is far higher than the material strength, and the material behavior is similar to the behavior of compressible liquid, in the region of impact. For hypervelocity impacting, the effect of compression, even the effect of phase transition may play an important part.As to discuss the effect of phase transition during hypervelocity impacting, the GRAY equation of state (EOS) was brought in the SPH program, and was applied in the simulation of hypervelocity impacting, in this paper. By comparing the results gotten from the GRAY EOS and the Tillotson EOS, some conclusions were found as follows:1. Under low velocities, the shape characteristics parameters of debris clouds given by the GRAY EOS accord with the corresponding results gotten by the Tillotson EOS, which shows that, the GRAY EOS is fit for being applied in numerical simulations of hypervelocity impacting.2. The effect of phase transition in hypervelocity impacting leads to differences between the results given by the two EOSs, which is shown by the shape, mass, velocity and momentum characteristics of debris clouds obtained from the numerical simulation with the two EOSs.3. The distribution of the material density, pressure, temperature and phase, and the region, where phase transition of melting and vaporizing happened, and where the ejected debris came, were offered in this paper.4. The protection capability of the Whipple structure is sensitive to the material phase transition and thermal softening, which is shown by the comparation of the results of the numerical simulation on the protection capability of the Whipple structure with the two EOSs.更多还原