A grain-scale study of spall in brittle materials

摘要

The evolution of spall for a brittle mate-rial is investigated under variance of anisotropy, grainboundary fracture energy, and loading. Because spalloccurs in the interior of the specimen, fundamentalstudies of crack nucleation and growth are neededto better understand surface velocity measurements.Within a cohesive approach to fracture, we illustratethat for anisotropic materials, increases in the frac-ture energy cause a transition in crack nucleation fromtriple-points to entire grain boundary facets. Analysisof idealized flaws reveals that while crack initiationand acceleration are strong functions of the fractureenergy, flaws soon reach speeds on the order of theRayleigh wave speed. Finally, simulated surface veloc-ities of spalled configurations are correlated withmicrostructural evolution. These fundamental studiesof nucleation, growth, and spall attempt to link atomicseparation to the macroscopic spall strength and pro-vide a computational framework to examine the evo-lution of spall and the impact on the simulated surface velocity field.