|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1997 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1996 : ¥400,000 (Direct Cost : ¥400,000)
The purpose of the research is to build a physical model that describes microtribological phenomena in a nano-scale material removal process. This atomistic model enables us to deal with dynamical phenomena of friction, wear and lubrication followed by elastic-plastic deformation, fracture and chemical reaction at surfaces/interfaces. The major results obtained are as follows :
1.Postulating interatomic force based on the Morse potential, a (111) plane of a copper single crystal is orthogonally machined in the direction of . Existing vacancies and edge dislocations in the crystal result in further disorder of the lattice structure and an increase in cutting forces. In the case of the duplex machining of the perfect crystal, displacement of the work atoms is limited to at or just below the finished surface. It is concluded that a prerequisite for a damage-free surface is that the work material should be as pure and perfect as possible. Lubrication between the tool and work atoms is
a crucial factor as well.
2.The bubble raft method according to Bragg and Nye has been employed to investigate the nano-scale cutting mechanisms of soap bubbles as well to make a comparison with MD simulations of a copper single crystal. Qualitative agreement can be seen with respect to basic cutting phenomena, including chip formation subsurface damage in which a similar deformation mechanism through dislocations plays a primary role. The interaction between the tool and work is also a key factor in nano-scale machining.
3.The existing two-dimensional MD simulation program has successfully been extended to a three-dimensional one in which computer graphics for visualization has also been developed as application software of Windows95. Using the simulation system, more realistic tribological phenomena have been clarified, such as diffusion of the removed work atoms toward the machined surface and re-adhesion of the worn tool atoms on the tool and work surfaces.