Modeling Spherical Indentation Experiments onto Silicon Carbide

This article presents computational modeling and analysis of the Hertzian spherical indentation experiment. A spherical diamond indenter is used to indent silicon carbide to various levels of indentation. Indentation depths of δ = 7 μm (experimental level) to depths greater than δ = 50 μm are presented. The EPIC code is used to model the indentation process, where the indenter is assumed to be elastic and the JH-1 ceramic model is used to represent the silicon carbide. The computed result for δ = 7 μm shows good correlation to the experiment for both loading and unloading. The damage process is presented and identifies when initial yielding occurs, the extent of damage at peak load, and additional damage that occurs from unloading. A noteworthy result is the determination of the pressure levels that occur. Pressures of over 10 GPa are produced, which are levels generally only attained through ballistic impact. Computed results are also presented for very deep indentations (δ= 52 μm). The results show a damage process that includes the development of ring cracks and material failure. The effect of strength and damage is also presented by varying JH-1 model parameters. The indentation response is sensitive to the intact strength when large plastic strains are produced. It appears that much larger indentations (δ ≫ 7 μm) are needed to understand the damage and failure processes in silicon carbide.