金属微层裂模拟中的抗拉伸不稳定人为应力方法  

Artificial stress method resistance to tensile instability in simulating metal microspalling

作　　者：刘军[1] 曹衍闯 熊俊[1] 王裴[1,2] LIU Jun;CAO YanChuang;XIONG Jun;WANG Pei(Institute of Applied Physics and Computational Mathematics,Beijing,100094,China;Center for Applied Physics and Technology of Peking University,Beijing 100871,China)

机构地区：[1]北京应用物理与计算数学研究所,北京100094 [2]北京大学应用物理与技术研究中心,北京100871

出　　处：《中国科学：物理学、力学、天文学》2022年第2期65-75,共11页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：于敏基金(编号:TCYM1820-02);国防基础科研核基础科学挑战计划(编号:TZ2018001)资助项目。

摘　　要：金属微层裂是金属在熔化状态下近表面物质的一种拉伸破坏现象,由于该问题的复杂性,一直以来模拟与实验的定量化对比存在难度.本文使用有限元方法模拟了爆轰冲击金属锡微层裂现象,发现微层裂区的模拟出现非物理现象,从而导致自由面速度和微层裂区密度分布均难以比对实验自由面DPS测速及X光结果.针对有限元模拟中出现的微层裂区密度、速度不连续等非物理现象,本文提出了一种抗拉伸不稳定人为应力方法.引入抗拉伸不稳定人为应力后的模拟结果表明:金属微层裂区密度、速度连续性有极大改善,自由面网格脱离现象得到有效抑制,在密度分布及自由面速度上均能够与实验较好符合.通过定量化对比分析认为,虽然抗拉伸不稳定人为应力是并不真实存在的虚假应力,但其作用于金属微层裂稀疏区能够达到稳定计算、减弱或消除非物理现象的作用,具有作用范围限定强、幅值小、不影响原格式守恒性等特点.本文研究突破了金属微层裂模拟与实验难以定量对比的瓶颈问题,为金属微层裂动力学规律分析及物理模型研究提供了重要的模拟技术支撑.Metal microspalling is a phenomenon caused by the tensile failure of near-surface materials in molten metals. To study the dynamics of metal microspalling, the simulation results should be quantitatively compared with the experimental results. However, because of the problem’s complexity, the quantitative simulation is challenging. In this paper, the finite element method is used to simulate the detonation-driven metal tin microspalling phenomenon. Because of some nonphysical phenomena in the simulation, it is challenging to compare the velocity of the free surface and the density distribution of the microspalling region to the displacement pin system(DPS) velocity and X-ray results in the experiment. Nonphysical phenomena, such as density and velocity discontinuity in simulating the microspalling region,can be reduced or eliminated via an artificial stress method that can resist tensile instability in simulation. An artificial stress limiter is used to limit its action range to the metal tensile region. The results show that the nonphysical phenomena in the tensile region of microspalling can be effectively restrained using the artificial stress method. The density and velocity continuity of the microspalling region are considerably improved, and the mesh separation of the free surface is effectively suppressed. The simulation results in the density distribution and free surface velocity correlate well with the tin microspalling experiment driven by detonation. The analysis shows that although the artificial stress method’s resistance to tensile instability is false stress that does not physically exist, it can achieve stable calculation, weaken or eliminate nonphysical phenomena. Moreover, it has the characteristics of strong action range limitation, small amplitude,and does not affect the original conservation. The work in this paper breaks through the bottleneck of quantitative comparison between simulation and experiment of metal microspalling;in addition, it provides an important simulation technique su

关 键 词：人为应力 拉伸不稳定 微层裂 有限元方法 

分 类 号：TG111[金属学及工艺—物理冶金]