Modeling of interface cracking in copper-graphite composites by MD and CFE method

Molecular dynamics (MD) method was used to study mechanical properties of copper-graphite composite interface. Mode I fracture of the interface of copper-graphite composite was modeled by considering fixed and free boundary conditions, which means slipping constraint conditions for atomic layers in the composite. The stress near crack tip and the energy changes of the system are obtained. Then a cohesive traction-separation law of copper-graphite interface can also be obtained by using the MD simulation. For the purpose of comparisons, a modeling of interfacial fracture of the composite by using a zero-thickness cohesive finite element (CFE) was carried out. It is found that there is a stress concentration but no singularity for the normal stress at the crack tip in interface obtained by using the present MD simulation and CFE method. While in the interface away from the crack tip, the obtained stress is consistent with the solution of classical interfacial fracture mechanics.