Molecular Dynamics Simulation Studies of Fracture in Two Dimensions
Abstract
Computer Molecular Dynamics (CMD) simulation has been applied to the study of fracture in a two-dimensional system. The system was composed of an atomic crack tip embedded in an infinite continuum medium under an external tensilestress (mode-I fracture). The structure and properties of the crack tip have been analyzed for materials characterized by several types of interatomic potential functions. This technique provides a unique way of investigating the non-linear atomic effects around the crack tip. A computer program has been developed which can be applied to any system of classical particles, crystalline solids, liquids or gases, under a wide range of boundary conditions, periodic, free, fixed and flexible boundaries. In particular, two kinds of boundary conditions have been employed in the study of the crack tip structure and stability in a two-dimensional triangular lattice. One is a fixed boundary condition which consists of fixing the particles at the boundaries according to a continuum elasticity solution and relaxing the system by introducing a viscous damping in the equations of motion. The second procedure is a flexible boundary condition which treats the simulation region as a discrete system embedded in a continuum. A linear Green's function is used to relax the forces arising from interactions between the atomic region and the continuum. This method is shown to be efficient and accurate in the determination of crack configurations in brittle materials. It is potentially useful for the study of other defect properties. The critical stress necessary to propagate a crack of finite length has been determined in the case of brittle materials. Higher values than those predicted by the Griffith theory have been obtained. The results seem to be very sensitive to the assumptions about interactions between the crack surfaces.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1980
- Accession Number
- ADA541803
Entities
People
- Benito De Celis
Organizations
- Massachusetts Institute of Technology