Artificial stress method resistance to tensile instability in simulating metal microspalling

Abstract

<p indent=0mm>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 support for dynamic analysis and physical model research of metal microspalling.