Brittle fracture in silicon is simulated with molecular dynamics utilizing a modified embedded atom method potential. The simulations produce propagating crack speeds that are in agreement with previous experimental results over a large range of fracture energy. The dynamic fracture toughness is found to be equal to the energy consumed by creating surfaces and lattice defects in agreement with theoretical predictions. The dynamic fracture toughness is approximately of the static strain energy release rate, which results in a limiting crack speed of of the Rayleigh wave speed.

Indentation of ceramic materials with smooth indenters such as parabolae of revolution and spheres can be conducted in the elastic regime to relatively high loads. Ceramic single crystals thus provide excellent calibration media for load and depth-sensing indentation testing; however, they are generally anisotropic and a complete elastic analysis is cumbersome. This study presents a simplified procedure for the determination of the stiffness of contact for the indentation of an anisotropic half-space by a rigid frictionless parabola of revolution which, to first order, approximates spherical indentation. Using a similar approach, a new procedure is developed for analysing conical indentation of anisotropic elastic media. For both indenter shapes, the contact is found to be elliptical, and equations are determined for the size, shape and orientation of the ellipse and the indentation modulus.