Papers by Akinjide Oluwajobi
The effect of the variation of cutting velocity on the nanometric machining of copper workpiece w... more The effect of the variation of cutting velocity on the nanometric machining of copper workpiece with diamond tool was studied using the Molecular Dynamics (MD) simulation. The copper-copper interactions were modelled by the EAM potential and the copper-diamond interactions were modelled by the Lennard-Jones (LJ) potential. The diamond tool was modelled as a deformable body and the Tersoff potential was applied for the carboncarbon interactions. The tangential and the normal force components increase with increase in cutting velocity. Also, the average temperature increases with increase in velocity. However, the force ratio increases and decreases, depending on the velocity interval.
Automation and Computing (ICAC), …, 2011
Key Engineering Materials, 2011
The multi-pass nanometric machining of copper with diamond tool was carried out using the Molecul... more The multi-pass nanometric machining of copper with diamond tool was carried out using the Molecular Dynamics (MD) simulation. The copper-copper interactions were modelled by the EAM potential and the copper-diamond interactions were modelled by the Morse potential. The diamond tool was modelled as a deformable body and the Tersoff potential was applied for the carbon-carbon interactions. It was observed that the average tangential and the normal components of the cutting forces reduced in the consecutive cutting passes. Also, the lateral force components are affected by atomic vibrations and the cross sectional area during the cutting process.
Journal of Physics: Conference Series, 2012
This paper presents recent investigation of acoustic emission (AE) behaviours in grinding process... more This paper presents recent investigation of acoustic emission (AE) behaviours in grinding processes. It demonstrated the acoustic emission features characterized in time and frequency domain are influenced by thermal behaviours of materials. By control laser conditions, the temperature elevation under laser irradiation can be similar to that in a grinding process. Therefore, an innovative concept that grinding process can be
International Journal of Abrasive Technology, 2013
The minimum depth of cut (MDC) is a major limiting factor on achievable accuracy in nanomachining... more The minimum depth of cut (MDC) is a major limiting factor on achievable accuracy in nanomachining, because the generated surface roughness is primarily attributed to the ploughing process when the uncut chip thickness is less than the MDC. This paper presents the material removal in a nanomachining process, where a sharp diamond tool with an edge radius of few atoms acts on a crystalline copper workpiece. The molecular dynamics (MD) simulation results show the phenomena of rubbing, ploughing and cutting. The formation of chip occurred from the depth of cut thickness of 1~1.5 nm. Also, the effects of the interatomic potentials on the MDC have been presented.
This paper presents some research results of the application of finite element method and molecul... more This paper presents some research results of the application of finite element method and molecular dynamics in the simulation of grinding surface creation. The comparison of these two methods shows that both methods could illustrate the material removal phenomena and provide useful information of grinding mechanics, but they have different feasible application arranges depending on the level of size scales. The investigation demonstrated that rubbing hypothesis of grinding material removal mechanism is valid at all size level even down to nanometre level. Further investigation areas are identified in the paper.
This paper presents the use of Cellular Automata (CA) for modelling micro abrasive machining. A o... more This paper presents the use of Cellular Automata (CA) for modelling micro abrasive machining. A one-dimensional CA was initially used to model the workpiece, as having different heights, to represent the roughness; and the forces from the abrasive grits were modelled to randomly erode the workpiece, as such smoothening out and polishing the surface. The modelling was then extended further to two dimensions. Results of the simulations have shown that the mean heights of the peaks, depicting the surface roughness of the workpiece and the mean standard deviation sharply decrease as time evolved. Good surface finish was always observed just after 20 pass steps. The work carried out has demonstrated that it is possible to model and simulate abrasive machining processes by implementing simple rules of cellular automata.
The concept of Minimum Depth of Cut (MDC) is that the depth of cut must be over a certain critica... more The concept of Minimum Depth of Cut (MDC) is that the depth of cut must be over a certain critical thickness before any chip is formed. It is actually a major limiting factor on achievable accuracy in nanomachining, because the generated surface roughness is primarily attributed to the ploughing process when the uncut chip thickness is less than the MDC. This paper presents an analysis of a cutting process where a sharp pointed diamond tool with an edge radius of an atom acts on a crystalline copper workpiece. From the molecular dynamics (MD) simulation results, the phenomena of rubbing, ploughing and cutting were observed. The formation of chip occurred from the depth of cut thickness of 30.0 Ǻ (3nm).
The effects of cutting edge shapes on the phenomena of rubbing and ploughing in nano-abrasive mac... more The effects of cutting edge shapes on the phenomena of rubbing and ploughing in nano-abrasive machining were investigated. The shapes under investigation include flat, spherical and trapezoidal shapes. The tool with the flat end geometry shows a fast initiation of ploughing, because it has the largest surface area to engage more atoms. It doesn’t show rubbing phenomenon at the (initial) depth of cut of 0.5 Angstroms. The tool with the trapezoidal end has the lowest average cutting force and the tool with the flat end has the highest average cutting force.
The development of ultra–precision processes which can achieve excellent surface finish and toler... more The development of ultra–precision processes which can achieve excellent surface finish and tolerance at nanometre level is now a critical requirement for many applications in medical, electronics and energy industry. Presently, it is very difficult to observe the diverse microscopic physical phenomena occurring in nanometric machining through experiments. The use of Molecular Dynamics (MD) simulation has proved to be an effective tool for the prediction and the analysis of these processes at the nanometre scale. The complexity and the cost of experimental investigation have made this approach even more suitable as simulation results sometimes point interesting directions for experimentation.
Solid State Phenomena
The study of nanoscale machining phenomena and processes are effectively been carried out by usin... more The study of nanoscale machining phenomena and processes are effectively been carried out by using the molecular dynamics (MD) simulation. The MD provides explanation of material behaviour that are difficult to observe or even impossible through experiments. To carry out reliable simulations, the method depends on critical issues, which include the choice of appropriate interatomic potentials and the integration time step. The selection of the timestep in the MD simulation of nanomachining is the major focus of this investigation. A too low timestep would be computationally expensive and also a too high timestep would cause chaotic behaviour in the simulation. Computational experiments were conducted to check for the range of timestep that is appropriate for the simulation of nanomachining of copper. It was observed from the total energy variations, that time step in the range of 0.1 to 0.4 fs could be used to procure stable simulations in copper, for the configuation employed.
The development of ultra-precision processes which can achieve excellent surface finish and toler... more The development of ultra-precision processes which can achieve excellent surface finish and tolerance at the nanometre level is now a critical requirement for many industrial applications. Presently, it is very difficult to observe the diverse microscopic physical phenomena occurring in nanometric machining through experiments. The use of Molecular Dynamics (MD) simulation has proved to be an effective tool for the prediction and the analysis of these processes at the nanometre scale. The crucial task in a MD simulation is the selection of the potential function. The lack of clear understanding about the scope and the limitations of a given potential function may lead to nonsensical results. This article presents the backgrounds of popular potentials used in the modelling of materials processes and the algorithms for the solution of the equations encountered in the simulation. Current applications of MD in abrasive machining are reviewed.
Current Nanoscience, 2016
The version presented here may differ from the published version or from the version of the recor... more The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.
Key Engineering Materials, Feb 20, 2013
The development of ultra-precision processes which can achieve excellent surface finish and toler... more The development of ultra-precision processes which can achieve excellent surface finish and tolerance at the nanometre level is now a critical requirement for many industrial applications. Presently, it is very difficult to observe the diverse microscopic physical phenomena occurring in nanometric machining through experiments. The use of Molecular Dynamics (MD) simulation has proved to be an effective tool for the prediction and the analysis of these processes at the nanometre scale. The crucial task in a MD simulation is the selection of the potential function. The lack of clear understanding about the scope and the limitations of a given potential function may lead to nonsensical results. This article presents the backgrounds of popular potentials used in the modelling of materials processes and the algorithms for the solution of the equations encountered in the simulation. Current applications of MD in abrasive machining are reviewed.
Page 1. University of Huddersfield Repository Oluwajobi, Akinjide O. and Chen, Xun Cellular autom... more Page 1. University of Huddersfield Repository Oluwajobi, Akinjide O. and Chen, Xun Cellular automata modelling of micro abrasive machining. Original Citation Oluwajobi, Akinjide O. and Chen, Xun (2009) Cellular automata modelling of micro abrasive machining. ...
The effects of cutting edge shapes on the phenomena of rubbing and ploughing in nano-abrasive mac... more The effects of cutting edge shapes on the phenomena of rubbing and ploughing in nano-abrasive machining were investigated. The shapes under investigation include flat, spherical and trapezoidal shapes. The tool with the flat end geometry shows a fast initiation of ploughing, because it has the largest surface area to engage more atoms. It doesn't show rubbing phenomenon at the (initial) depth of cut of 0.5 Angstroms. The tool with the trapezoidal end has the lowest average cutting force and the tool with the flat end has the highest average cutting force.
Page 1. University of Huddersfield Repository Oluwajobi, Akinjide O. and Chen, Xun Simulation of ... more Page 1. University of Huddersfield Repository Oluwajobi, Akinjide O. and Chen, Xun Simulation of Abrasive Machining Using Molecular Dynamics Original Citation Oluwajobi, Akinjide O. and Chen, Xun (2009) Simulation of Abrasive Machining Using Molecular Dynamics. ...
Advanced Materials Research, 2012
This paper presents some research results of the application of finite element method and molecul... more This paper presents some research results of the application of finite element method and molecular dynamics in the simulation of grinding surface creation. The comparison of these two methods shows that both methods could illustrate the material removal phenomena and provide useful information of grinding mechanics, but they have different feasible application arranges depending on the level of size scales. The investigation demonstrated that rubbing hypothesis of grinding material removal mechanism is valid at all size level even down to nanometre level. Further investigation areas are identified in the paper.
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Papers by Akinjide Oluwajobi