Coupling of dynamic ductile damage and melting in shock-induced micro-spalling: Modeling and applications

Micro-spalling is a dynamic fragmentation process that is coupled with shock-induced overheating and melting. It has been observed in series of shock experiments and in several modern industrial applications such as inertial confinement fusion and laser-shock surface micromachining. Modeling micro-spalling is beyond the scope of traditional damage mechanics which ignores solid-liquid transformation. Here, for the first time, we develop a continuum model of micro-spalling by coupling hydroelastic-plastic-damage mechanics and high-pressure melting kinetics. A two-scale framework is proposed for modeling mechanical responses of partially melted materials in shock-induced micro-spalling. Temperature and pressure dependence of shock-induced melting rate is formulated. In modeling dynamic ductile damage, temperature and (partial) melting effects are involved. The model is implemented into a finite element code and used as a predictive tool to simulate plate impact spalling experiments on aluminum. The simulations reveal typical characteristics of micro-spalling resulted from coupling effects of dynamic damage and melting, concerning evolutions of damage and phase distributions and thermodynamic paths. The simulations are in good agreement with previous experiments and molecular dynamics simulations. Particularly, the calculated free surface velocity profiles and spall strengths are quantitatively consistent with experimental measurements in a wide range of initial temperature up to the melting point. These results indicate that the present model is a reasonable uniform description of spalling process, covering transition from classical solid spalling to melting-accomplished micro-spalling.

Automated summary

Researchers developed a continuum model of micro-spalling by coupling hydroelastic-plastic-damage mechanics and high-pressure melting kinetics, successfully simulating plate impact spalling experiments on aluminum while considering both damage and melting effects in the fracture process.