A molecular-dynamic approach to interface crack problem.

A molecular dynamic (MD) approach to interface crack problems is proposed. A 2-body interatomic potential which provides a linear elastic character to the solidis is used for both the bonded materials and the interface. It enables direct comparison of the molecular dynamic analysis with the continuum model. The critical state of the interface crack propagation is analyzed on the 2D dissimilar solid made up of closed-packed atoms. The elastic local displacement field at the interface crack-tip which is characterized by the stress intensity factors is used as the boundary condition for the MD-analysis. The analysis shows that the critical stress intensity factor fluctuates with a period of the lattice constant. In case of the weak interface where an interface failure occurs, the critical stress intensity factor is in good agreement with the value obtained by the interface fracture energy. However, under shear loading conditions, dislocations and other defects are introduced into the interface region, and critical stress intensity factor differs from the data of the fracture energy.