60,693 research outputs found
Consistent forcing scheme in the cascaded lattice Boltzmann method
In this paper, we give a more pellucid derivation for the cascaded lattice
Boltzmann method (CLBM) based on a general multiple-relaxation-time (MRT) frame
through defining a shift matrix. When the shift matrix is a unit matrix, the
CLBM degrades into an MRT LBM. Based on this, a consistent forcing scheme is
developed for the CLBM. The applicability of the non-slip rule, the
second-order convergence rate in space and the property of isotropy for the
consistent forcing scheme is demonstrated through the simulation of several
canonical problems. Several other existing force schemes previously used in the
CLBM are also examined. The study clarifies the relation between MRT LBM and
CLBM under a general framework
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Modelling and simulation on the tool wear in nanometric cutting
Tool wear is a significant factor affecting the machined surface quality. In this paper, a Molecular Dynamics (MD) simulation approach is proposed to model the wear of the diamond tool in nanometric cutting. It includes the effects of the cutting heat on the workpiece property. MD simulation is carried out to simulate the nanometric cutting of a single crystal silicon plate with the diamond tip of an Atomic Force Microscope (AFM). The wear mechanism is investigated by the calculation of the temperature, the stress in the diamond tip, and the analysis of the relationship between the temperature and sublimation energy of the diamond atoms and silicon atoms. Microstrength is used to characterize the wear resistance of the diamond tool. The machining trials on an AFM are performed to validate the results of the MD simulation. The results of MD simulation and AFM experiments all show that the thermo-chemical wear is the basic wear mechanism of the diamond cutting tool
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An investigation on the mechanics of nanometric cutting and the development of its test-bed
The mechanics of machining at a very small depth of cut (100 nm or less) is not
well understood. The chip formation physics, cutting forces generation, resulting
temperatures and the size effects significantly affect the efficiency of the process
and the surface quality of the workpiece. In this paper, the cutting mechanics
at nanometric scale are investigated in comparison with conventional cutting
principles. Molecular Dynamics (MD) is used to model and simulate the nanometric
cutting processes. The models and simulated results are evaluated and
validated by the cutting trials on an atomic force microscope (AFM).
Furthermore, the conceptual design of a bench-type ultraprecision machine tool
is presented and the machine aims to be a facility for nanometric cutting of threedimensional
MEMS devices. The paper concludes with a discussion on the potential
and applications of nanometric cutting techniques/equipment for the
predictabilty, producibility and productivity of manufacturing at the nanoscale
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