hassan elhofy - Academia.edu (original) (raw)

Papers by hassan elhofy

A literature review has been carried out to identify factors affecting the machinability of fibre... more A literature review has been carried out to identify factors affecting the machinability of fibre reinforced plastics (FRP) composites in general and carbon fibre reinforced plastics (CFRP) in particular. This includes the use of different cutting tool materials, tool geometry, and process variables together with aspects such as cutting forces, tool wear/life, cut quality/defects, cutting temperature, and surface integrity in both experimental and modelling approaches.

A growing interest in modelling and simulation of machining processes has been witnessed in the p... more A growing interest in modelling and simulation of machining processes has been witnessed in the past few decades. Smoothed particles hydrodynamics (SPH), one of the latest and developing methods used for that purpose, is a powerful technique that can be efficient in handling problems in which large deformation occurs. The current work aims to present and evaluate the use of SPH in modelling the machining processes. A coupled thermo-mechanical analysis of a 3D model is performed using LS-DYNA to predict the cutting forces during face turning of Ti6Al4V alloy, at different cutting speeds. The Johnson-Cook material constitutive model is used along with both linear polynomial and Gruneisen equations of state in order to accurately simulate the material behavior and investigate their effects on the results. The simulation results are validated using a previously published experimental work.

Advances in Manufacturing, 2021

Over the last few decades, the interest in modeling of machining processes has been growing. In t... more Over the last few decades, the interest in modeling of machining processes has been growing. In this regard, the smoothed particle hydrodynamics (SPH) method is one of the latest powerful techniques used for that purpose. The strength of SPH lies behind its accuracy in stress calculations and the ability to handle situations involving large amount of deformation, which is difficult to be tackled using traditional finite element methods. This work aims to present and evaluate the use of SPH method in modeling of high speed machining (HSM). A thermo-mechanical coupled analysis of both 2D and 3D models is performed using LS-DYNA. The simulation aims to predict the cutting forces and chip morphology during high speed orthogonal cutting of Ti6Al4V alloy. In order to accurately simulate the material behavior during cutting, Johnson-Cook material constitutive model is used. The results from SPH model are validated using published experimental data.

Materials Science Forum, 2017

Ultrasonic-Assisted Milling (UAM) combines the material removal mechanism of grinding and the mil... more Ultrasonic-Assisted Milling (UAM) combines the material removal mechanism of grinding and the milling kinematics with ultrasonic assistance. The process is suitable for hard-to-cut materials used in many industrial applications. UAM is a novel process, still under investigation to clarify the product accuracy and the process performance. This paper presents a literature review covering the development of the experimental work related to UAM. A summary of key research problems is concluded and a systematic study using the design of experiments is suggested in order to investigate the effects of the main process parameters on its performance.

International Journal of Machining and Machinability of Materials, 2019

Glass has an increasing demand in many industrial fields such as micro-channels and micro reactor... more Glass has an increasing demand in many industrial fields such as micro-channels and micro reactors in fluidic applications, lab-on-a-chip in medical applications, and micro lens arrays and optical devices. Machining of glass as one of hard-to-machine materials is challengeable due to its distinctive properties of high strength, hardness, and brittleness. Facing these challenges, ultrasonic-assisted milling (UAM); an advanced machining process; was provided for its effectiveness in machining such hard-to-machine materials. In this paper, the effects of feed rate, depth of cut, ultrasonic-vibration assistance, and cutting fluid on surface roughness in UAM of soda-lime glass compared with conventional milling (CM) were investigated. Results showed that, by introducing ultrasonic-vibration, higher surface roughness was obtained. The optimal cutting conditions were attained using response surface methodology. At the optimised parametric setting, the minimum surface roughness was found to be at wet conventional milling.

International Journal of Machining and Machinability of Materials, 2021

Recently, an ultrasonic vibration-assisted technique has been utilised to improve the hole-making... more Recently, an ultrasonic vibration-assisted technique has been utilised to improve the hole-making process of aerospace materials. However, there was a lack in discussing the effect of applying ultr...

Non-fossil fuel energy options can help humanity combat climate change and provide the opportunit... more Non-fossil fuel energy options can help humanity combat climate change and provide the opportunity for sustainable energy solutions. Non-fossil fuel energy options are diverse, ranging from renewables like solar, wind, geothermal, hydropower, biomass, ...

Preface xl Acknowledgments xvii List of Acronyms xix List of Symbols xxlii Chapter, 1. Material R... more Preface xl Acknowledgments xvii List of Acronyms xix List of Symbols xxlii Chapter, 1. Material Removal Processes

Volume 1: Processing, 2015

Over the last few decades, the interest in modeling of machining processes has been growing. In t... more Over the last few decades, the interest in modeling of machining processes has been growing. In this regard, the smoothed particle hydrodynamics (SPH) method is one of the latest powerful techniques used for that purpose. The strength of SPH lies behind its accuracy in stress calculations and the ability to handle situations involving large amount of deformation, which is difficult to be tackled using traditional finite element methods. This work aims to present and evaluate the use of SPH method in modeling of high speed machining (HSM). A thermo-mechanical coupled analysis of both 2D and 3D models is performed using LS-DYNA. The simulation aims to predict the cutting forces and chip morphology during high speed orthogonal cutting of Ti6Al4V alloy. In order to accurately simulate the material behavior during cutting, Johnson-Cook material constitutive model is used. The results from SPH model are validated using published experimental data.

Volume 2: Advanced Manufacturing, 2018

Machining of hard-to-cut materials to a high degree of accuracy and surface quality is one of the... more Machining of hard-to-cut materials to a high degree of accuracy and surface quality is one of the most critical operations when fabricating different state-of-the-art engineered components. Abrasive waterjet machining (AWJM) is one of the non-conventional technologies, which is increasingly gaining a reputation for machining hard-to-cut materials. Despite many phenomenological investigations, the dynamic characteristics of the abrasive waterjet and physical interactions with the machined surface have not been thoroughly investigated in the context of understanding the machining process. The kerf geometry has been associated with several abrasive waterjet input parameters, but its characteristics have remained speculative among many researchers. In the present study, the governing equations of two-phase abrasive waterjet flow and the interaction with the material surface are developed and numerically simulated. With the help of precisely developed user-defined functions (UDF), the ma...

International Journal of Machining and Machinability of Materials, 2019

Glass has an increasing demand in many industrial fields such as micro-channels and micro reactor... more Glass has an increasing demand in many industrial fields such as micro-channels and micro reactors in fluidic applications, lab-on-a-chip in medical applications, and micro lens arrays and optical devices. Machining of glass as one of hard-to-machine materials is challengeable due to its distinctive properties of high strength, hardness, and brittleness. Facing these challenges, ultrasonic-assisted milling (UAM); an advanced machining process; was provided for its effectiveness in machining such hard-to-machine materials. In this paper, the effects of feed rate, depth of cut, ultrasonic-vibration assistance, and cutting fluid on surface roughness in UAM of soda-lime glass compared with conventional milling (CM) were investigated. Results showed that, by introducing ultrasonic-vibration, higher surface roughness was obtained. The optimal cutting conditions were attained using response surface methodology. At the optimised parametric setting, the minimum surface roughness was found to be at wet conventional milling.

Fundamentals of Machining Processes, 2013

The electrolytic surface hardening process has been found to be a new development in the area of ... more The electrolytic surface hardening process has been found to be a new development in the area of surface heat treatments. This is more economical, easy to control and powerful than conventional surface heat treatment processes. This paper studied the electrolytic surface hardening process using a specimen of medium carbon steel AISI 1050 in an electrolyte of sodium carbonate. Different voltages of DC and pulsed DC are applied. After feasibility study, an apparatus was designed and fabricated to study this process. The effect of applied voltage, hardening time, gap distance between the electrode and specimen on surface hardness have been investigated in case of DC and pulsed DC operating conditions. Moreover, the effects of the frequency and duty cycle on hardness in case of pulsed DC operating condition have been investigated. A surface hardness of 900 HV has been achieved using electrolytic surface hardening process.

Solid State Phenomena, 2018

Ultrasonic-assisted drilling (UAD) is a new process used for producing holes in the hard-to-cut a... more Ultrasonic-assisted drilling (UAD) is a new process used for producing holes in the hard-to-cut and brittle materials at high accuracy and surface quality. In this paper, statistically designed experiments were conducted to study the machinability of soda glass in UAD. The machinability was measured in terms of the cutting power, surface roughness Ra and Rz and the linear tool wear. Machining conditions include UAD and conventional drilling (CD), abrasive tool concentration, feedrate, and spindle speed. Analysis of variance (ANOVA) defined the significant factors and their interactions, while statistical models were used to predict the process responses used for assessment of machinability indices.

Key Engineering Materials, 2014

Products such as parts of die sets and cutting tool inserts are normally produced with complex sh... more Products such as parts of die sets and cutting tool inserts are normally produced with complex shapes in materials of high hardness and wear resistance such as ceramics. Electro discharge machining (EDM) can be used to manufacture complex shapes in high hardness materials, but the material should be conductive. Being conductive, Aluminum oxide (Al2O3) based ceramics represent a good alternative for manufacturing hard complex shape parts. However, the integrity of the produced surfaces and the material removal rate need to be investigated. A full factorial experimental design was used to investigate the effect of some selected process variables, namely; pulse-on time, pulse-off time, and pulse current on specific EDM performance measures. The considered performance measures are; crater diameter (D), material removal rate (MRR), and average roughness value (Ra). An analysis of variance (ANOVA) test was carried out to evaluate the experimental results. Empirical models have been develo...

The International Journal of Advanced Manufacturing Technology, 2019

Electrochemical machining (ECM) uses a direct current (DC) at high density of 0.5-5 A/mm 2 which ... more Electrochemical machining (ECM) uses a direct current (DC) at high density of 0.5-5 A/mm 2 which is passed through the electrolytic solution that fills the gap between an anodic workpiece and a pre-shaped cathodic tool. At the anodic surface, metal is dissolved into metallic ions and thus as the tool moves towards the workpiece at a constant feed proportional to the dissolution rate of the anodic surface, then its shape is copied into the workpiece. During ECM, the electrolyte is forced to flow through a narrow interelectrode gap at high velocity of more than 5 m/s to intensify the mass/charge transfer through the sublayer near the anodic surface. The electrolyte removes the dissolution by-products, e.g., hydroxide of metal, heat, and gas bubbles generated in the interelectrode gap. These machining by-products affect the process accuracy, efficiency, stability, and productivity. Ensuring the continuous flushing of these products is, therefore, essential. One of these methods is through the use of pulsed voltage. Introducing vibrational motion, at low or ultrasonic frequency, to the tool/workpiece or the machining medium became a viable alternative for the evacuation of the machining products during the vibration-assisted ECM (VA-ECM). Other attempts to further enhance VA-ECM performance include the proper tool design, addition of abrasive particles to the electrolyte medium, and use of magnetic flux assistance. This paper reviews the principles of VA-ECM, main research directions, process parameters, and performance indicators. Numerous fields of VA-ECM which include micro-slotting, micro-drilling, macro-drilling, electrochemical wire cutting (ECWC), polishing and finishing, and micro-tool fabrication have been covered. Several mathematical and statistical modeling and optimization techniques have been also examined. The current paper also outlines possible trends for future research work.

Machine Tools and Operations, 2008

... www.crcpress.com Page 6. To our grandsons and granddaughters, Omar, Youssef, Nour, Anourine, ... more ... www.crcpress.com Page 6. To our grandsons and granddaughters, Omar, Youssef, Nour, Anourine, Fayrouz, and Yousra Page 7. Page 8. Contents Preface .....xix ...

A literature review has been carried out to identify factors affecting the machinability of fibre... more A literature review has been carried out to identify factors affecting the machinability of fibre reinforced plastics (FRP) composites in general and carbon fibre reinforced plastics (CFRP) in particular. This includes the use of different cutting tool materials, tool geometry, and process variables together with aspects such as cutting forces, tool wear/life, cut quality/defects, cutting temperature, and surface integrity in both experimental and modelling approaches.

A growing interest in modelling and simulation of machining processes has been witnessed in the p... more A growing interest in modelling and simulation of machining processes has been witnessed in the past few decades. Smoothed particles hydrodynamics (SPH), one of the latest and developing methods used for that purpose, is a powerful technique that can be efficient in handling problems in which large deformation occurs. The current work aims to present and evaluate the use of SPH in modelling the machining processes. A coupled thermo-mechanical analysis of a 3D model is performed using LS-DYNA to predict the cutting forces during face turning of Ti6Al4V alloy, at different cutting speeds. The Johnson-Cook material constitutive model is used along with both linear polynomial and Gruneisen equations of state in order to accurately simulate the material behavior and investigate their effects on the results. The simulation results are validated using a previously published experimental work.

Advances in Manufacturing, 2021

Over the last few decades, the interest in modeling of machining processes has been growing. In t... more Over the last few decades, the interest in modeling of machining processes has been growing. In this regard, the smoothed particle hydrodynamics (SPH) method is one of the latest powerful techniques used for that purpose. The strength of SPH lies behind its accuracy in stress calculations and the ability to handle situations involving large amount of deformation, which is difficult to be tackled using traditional finite element methods. This work aims to present and evaluate the use of SPH method in modeling of high speed machining (HSM). A thermo-mechanical coupled analysis of both 2D and 3D models is performed using LS-DYNA. The simulation aims to predict the cutting forces and chip morphology during high speed orthogonal cutting of Ti6Al4V alloy. In order to accurately simulate the material behavior during cutting, Johnson-Cook material constitutive model is used. The results from SPH model are validated using published experimental data.

Materials Science Forum, 2017

Ultrasonic-Assisted Milling (UAM) combines the material removal mechanism of grinding and the mil... more Ultrasonic-Assisted Milling (UAM) combines the material removal mechanism of grinding and the milling kinematics with ultrasonic assistance. The process is suitable for hard-to-cut materials used in many industrial applications. UAM is a novel process, still under investigation to clarify the product accuracy and the process performance. This paper presents a literature review covering the development of the experimental work related to UAM. A summary of key research problems is concluded and a systematic study using the design of experiments is suggested in order to investigate the effects of the main process parameters on its performance.

International Journal of Machining and Machinability of Materials, 2019

Glass has an increasing demand in many industrial fields such as micro-channels and micro reactor... more Glass has an increasing demand in many industrial fields such as micro-channels and micro reactors in fluidic applications, lab-on-a-chip in medical applications, and micro lens arrays and optical devices. Machining of glass as one of hard-to-machine materials is challengeable due to its distinctive properties of high strength, hardness, and brittleness. Facing these challenges, ultrasonic-assisted milling (UAM); an advanced machining process; was provided for its effectiveness in machining such hard-to-machine materials. In this paper, the effects of feed rate, depth of cut, ultrasonic-vibration assistance, and cutting fluid on surface roughness in UAM of soda-lime glass compared with conventional milling (CM) were investigated. Results showed that, by introducing ultrasonic-vibration, higher surface roughness was obtained. The optimal cutting conditions were attained using response surface methodology. At the optimised parametric setting, the minimum surface roughness was found to be at wet conventional milling.

International Journal of Machining and Machinability of Materials, 2021

Recently, an ultrasonic vibration-assisted technique has been utilised to improve the hole-making... more Recently, an ultrasonic vibration-assisted technique has been utilised to improve the hole-making process of aerospace materials. However, there was a lack in discussing the effect of applying ultr...

Non-fossil fuel energy options can help humanity combat climate change and provide the opportunit... more Non-fossil fuel energy options can help humanity combat climate change and provide the opportunity for sustainable energy solutions. Non-fossil fuel energy options are diverse, ranging from renewables like solar, wind, geothermal, hydropower, biomass, ...

Preface xl Acknowledgments xvii List of Acronyms xix List of Symbols xxlii Chapter, 1. Material R... more Preface xl Acknowledgments xvii List of Acronyms xix List of Symbols xxlii Chapter, 1. Material Removal Processes

Volume 1: Processing, 2015

Over the last few decades, the interest in modeling of machining processes has been growing. In t... more Over the last few decades, the interest in modeling of machining processes has been growing. In this regard, the smoothed particle hydrodynamics (SPH) method is one of the latest powerful techniques used for that purpose. The strength of SPH lies behind its accuracy in stress calculations and the ability to handle situations involving large amount of deformation, which is difficult to be tackled using traditional finite element methods. This work aims to present and evaluate the use of SPH method in modeling of high speed machining (HSM). A thermo-mechanical coupled analysis of both 2D and 3D models is performed using LS-DYNA. The simulation aims to predict the cutting forces and chip morphology during high speed orthogonal cutting of Ti6Al4V alloy. In order to accurately simulate the material behavior during cutting, Johnson-Cook material constitutive model is used. The results from SPH model are validated using published experimental data.

Volume 2: Advanced Manufacturing, 2018

Machining of hard-to-cut materials to a high degree of accuracy and surface quality is one of the... more Machining of hard-to-cut materials to a high degree of accuracy and surface quality is one of the most critical operations when fabricating different state-of-the-art engineered components. Abrasive waterjet machining (AWJM) is one of the non-conventional technologies, which is increasingly gaining a reputation for machining hard-to-cut materials. Despite many phenomenological investigations, the dynamic characteristics of the abrasive waterjet and physical interactions with the machined surface have not been thoroughly investigated in the context of understanding the machining process. The kerf geometry has been associated with several abrasive waterjet input parameters, but its characteristics have remained speculative among many researchers. In the present study, the governing equations of two-phase abrasive waterjet flow and the interaction with the material surface are developed and numerically simulated. With the help of precisely developed user-defined functions (UDF), the ma...

International Journal of Machining and Machinability of Materials, 2019

Glass has an increasing demand in many industrial fields such as micro-channels and micro reactor... more Glass has an increasing demand in many industrial fields such as micro-channels and micro reactors in fluidic applications, lab-on-a-chip in medical applications, and micro lens arrays and optical devices. Machining of glass as one of hard-to-machine materials is challengeable due to its distinctive properties of high strength, hardness, and brittleness. Facing these challenges, ultrasonic-assisted milling (UAM); an advanced machining process; was provided for its effectiveness in machining such hard-to-machine materials. In this paper, the effects of feed rate, depth of cut, ultrasonic-vibration assistance, and cutting fluid on surface roughness in UAM of soda-lime glass compared with conventional milling (CM) were investigated. Results showed that, by introducing ultrasonic-vibration, higher surface roughness was obtained. The optimal cutting conditions were attained using response surface methodology. At the optimised parametric setting, the minimum surface roughness was found to be at wet conventional milling.

Fundamentals of Machining Processes, 2013

The electrolytic surface hardening process has been found to be a new development in the area of ... more The electrolytic surface hardening process has been found to be a new development in the area of surface heat treatments. This is more economical, easy to control and powerful than conventional surface heat treatment processes. This paper studied the electrolytic surface hardening process using a specimen of medium carbon steel AISI 1050 in an electrolyte of sodium carbonate. Different voltages of DC and pulsed DC are applied. After feasibility study, an apparatus was designed and fabricated to study this process. The effect of applied voltage, hardening time, gap distance between the electrode and specimen on surface hardness have been investigated in case of DC and pulsed DC operating conditions. Moreover, the effects of the frequency and duty cycle on hardness in case of pulsed DC operating condition have been investigated. A surface hardness of 900 HV has been achieved using electrolytic surface hardening process.

Solid State Phenomena, 2018

Ultrasonic-assisted drilling (UAD) is a new process used for producing holes in the hard-to-cut a... more Ultrasonic-assisted drilling (UAD) is a new process used for producing holes in the hard-to-cut and brittle materials at high accuracy and surface quality. In this paper, statistically designed experiments were conducted to study the machinability of soda glass in UAD. The machinability was measured in terms of the cutting power, surface roughness Ra and Rz and the linear tool wear. Machining conditions include UAD and conventional drilling (CD), abrasive tool concentration, feedrate, and spindle speed. Analysis of variance (ANOVA) defined the significant factors and their interactions, while statistical models were used to predict the process responses used for assessment of machinability indices.

Key Engineering Materials, 2014

Products such as parts of die sets and cutting tool inserts are normally produced with complex sh... more Products such as parts of die sets and cutting tool inserts are normally produced with complex shapes in materials of high hardness and wear resistance such as ceramics. Electro discharge machining (EDM) can be used to manufacture complex shapes in high hardness materials, but the material should be conductive. Being conductive, Aluminum oxide (Al2O3) based ceramics represent a good alternative for manufacturing hard complex shape parts. However, the integrity of the produced surfaces and the material removal rate need to be investigated. A full factorial experimental design was used to investigate the effect of some selected process variables, namely; pulse-on time, pulse-off time, and pulse current on specific EDM performance measures. The considered performance measures are; crater diameter (D), material removal rate (MRR), and average roughness value (Ra). An analysis of variance (ANOVA) test was carried out to evaluate the experimental results. Empirical models have been develo...

The International Journal of Advanced Manufacturing Technology, 2019

Electrochemical machining (ECM) uses a direct current (DC) at high density of 0.5-5 A/mm 2 which ... more Electrochemical machining (ECM) uses a direct current (DC) at high density of 0.5-5 A/mm 2 which is passed through the electrolytic solution that fills the gap between an anodic workpiece and a pre-shaped cathodic tool. At the anodic surface, metal is dissolved into metallic ions and thus as the tool moves towards the workpiece at a constant feed proportional to the dissolution rate of the anodic surface, then its shape is copied into the workpiece. During ECM, the electrolyte is forced to flow through a narrow interelectrode gap at high velocity of more than 5 m/s to intensify the mass/charge transfer through the sublayer near the anodic surface. The electrolyte removes the dissolution by-products, e.g., hydroxide of metal, heat, and gas bubbles generated in the interelectrode gap. These machining by-products affect the process accuracy, efficiency, stability, and productivity. Ensuring the continuous flushing of these products is, therefore, essential. One of these methods is through the use of pulsed voltage. Introducing vibrational motion, at low or ultrasonic frequency, to the tool/workpiece or the machining medium became a viable alternative for the evacuation of the machining products during the vibration-assisted ECM (VA-ECM). Other attempts to further enhance VA-ECM performance include the proper tool design, addition of abrasive particles to the electrolyte medium, and use of magnetic flux assistance. This paper reviews the principles of VA-ECM, main research directions, process parameters, and performance indicators. Numerous fields of VA-ECM which include micro-slotting, micro-drilling, macro-drilling, electrochemical wire cutting (ECWC), polishing and finishing, and micro-tool fabrication have been covered. Several mathematical and statistical modeling and optimization techniques have been also examined. The current paper also outlines possible trends for future research work.

Machine Tools and Operations, 2008

... www.crcpress.com Page 6. To our grandsons and granddaughters, Omar, Youssef, Nour, Anourine, ... more ... www.crcpress.com Page 6. To our grandsons and granddaughters, Omar, Youssef, Nour, Anourine, Fayrouz, and Yousra Page 7. Page 8. Contents Preface .....xix ...