Numerical study of the temperature and porosity effects on the fracture propagation in a 2D network of elastic bonds

This article reports results concerning the fracture of a 2d triangular lattice of atoms linked by springs. The lattice is submitted to controlled strain tests and the influence of both porosity and temperature on failure is investigated. The porosity is found on one hand to decrease the stiffness of the specimen but on the other hand it increases the deformation sustained prior to failure. Temperature is shown to control the ductility due to the presence of cavities that grow and merge. The rough surfaces resulting from the propagation of the crack exhibit self-affine properties with a roughness exponent zeta = 0.59 +/- 0.07 over a range of length scales which increases with temperature. Large cavities also have rough walls which are found to be fractal with a dimension, D, which evolves with the distance from the crack tip. For large distances, D is found to be close to 1.5, and close to 1.0 for cavities just before their coalescence with the main crack.