非对称冲击-卸载实验中纵波声速的特征线分析方法  

Characteristic method to infer the high-pressure sound speed in a nonsymmetric impact and release experiment

作　　者：潘昊[1,2] 吴子辉[1] 胡晓棉[1] 

机构地区：[1]北京应用物理与计算数学研究所计算物理重点实验室,北京100088 [2]中国工程物理研究院研究生部,北京100088

出　　处：《物理学报》2016年第11期176-181,共6页Acta Physica Sinica

摘　　要：材料高压声速是获取材料在冲击下的剪切模量、强度和相变信息的重要物理量,对于研究材料在高速冲击下的行为非常重要.由于飞片、样品和窗口材料阻抗失配等因素,传统的声速分析方法无法对非对称冲击-卸载实验中单样品的窗口界面速度进行准确的分析.本文在反向特征线方法的基础上,考虑了飞片与样品、样品和窗口界面的相互作用,建立了适合于仅含单一厚度样品的非对称冲击-卸载实验的特征线声速分析方法,通过对数值实验给出的速度剖面的分析表明,该方法能够较为准确地获得待测材料高压下的声速及卸载路径.Sound speed is of great importance for high velocity impact phenomena because it is a fundamental parameter to deduce the shear moduli,strengths and phase transitions of materials at high pressure.It has attracted much attention because of significant challenges to experiment and simulation.In practice,with the development of laser interferometer measurement system,one can obtain velocity-time histories of windowed-surfaces or free surfaces with high resolution in shock or ramp compression and unload experiments.This development provides a possible way to infer the sound speed from these velocity profiles.The key problem is to build valid analysis technique to extract the sound speed.Commonly used Lagrangian analysis methods include backward integration method,incremental impedance matching method,transfer function method and backward characteristic analysis method.However,all of these methods hardly infer the right results from the nonsymmetric impact and release experiment with only one depth of material due to the complex impedance mismatch among a flyer,sample and window.Some decreasing impedance mismatch techniques have been developed for the experiments including reverse impact or using a high strength flyer,but these techniques will limit the pressure range or need a newly designed gun with large caliber.In fact,the traditional backward characteristic analysis method only considers the sample/window interaction while bending of the incoming characteristics due to impedance difference between the flyer and sample is always ignored,which causes a distortion to the loading condition of samples.Thus in this work,we add forward characteristics to describe rarefaction wave reflection at the flyer/sample interface.Then a reasonable loading-releasing in-situ velocity profile of the interface can be derived from this improvement.We use the improved/tradition characteristics and incremental impedance matching method to analyze a synthetic nonsymmetric impact experiment in which the flyer,sample and window are of Al,

关 键 词：声速 特征线方法 冲击加载 

分 类 号：TB302[一般工业技术—材料科学与工程]