naemeh fakhar | Bu-Ali Sina University (original) (raw)

Papers by naemeh fakhar

Journal of Holistic Nursing and Midwifery, 2009

Medical science experts have reached scientific and technological improvements in recent ‎decades... more Medical science experts have reached scientific and technological improvements in recent ‎decades and have turned surgery into a routine treatment by controlling its complications. ‎Cumulative changes in surgery resulted in decreased pain and discomfort and controlled ‎complications. The developmental path and changes have resulted in endoscopic with minimal ‎invasive surgery (MIS) in which only few small incisions are made on the body and surgery is ‎done through video control which otherwise required more and larger incision with more ‎complication. But this method with all the usefulness has some problems such as discrepancy ‎between surgeon's eye and hand, indirect and two dimensional vision, limited degree of ‎freedom of instruments and surgeon's fatigue. In addition this type of surgery needs complete ‎education and skill. The sum of these factors limits the use of MIS. In order to overcome these ‎problems, robotic surgery method is invented. In this method like MIS, a...

Applied Physics A, 2016

Despite valuable electrical characteristics, the use of pure aluminum in different applications h... more Despite valuable electrical characteristics, the use of pure aluminum in different applications has been limited due to its low strength. Non-equal channel angular pressing (NECAP) is a recently proposed severe plastic deformation process with greater induced plastic strain and, consequently, better grain refinement in the product, compared with the well-known equal channel angular pressing technique. This research is concerned with the effects of the process temperature and ram velocity on the mechanical, workability and electrical properties of AA1060 aluminum alloy. Increasing the process temperature can concurrently increase the workability, ductility and electrical conductivity, while it has a reverse influence on the strength of the NECAPed specimen, although the strengths of all the products are higher than the as-received alloy. The influence of the ram speed on the mechanical properties of the processed samples is lower than the process temperature. Finally, a compromised process condition is introduced in order to attain a good combination of workability and strength with well-preserved electrical conductivity for electrical applications of components made of pure aluminum.

Materials & Design, 2015

Abstract Superplastic behavior of fine and ultra fine-grained AA5083 Al alloy was examined using ... more Abstract Superplastic behavior of fine and ultra fine-grained AA5083 Al alloy was examined using the shear punch test. To achieve fine- and ultra fine-grained microstructures, a relatively new severe plastic deformation (SPD) process, namely Double Equal Channel Lateral Extrusion (DECLE) was employed. The strain rate sensitivity indices (m) of samples were evaluated after 1, 2, 4, and 6 passes for shear strain rates in the range of 3 × 10− 3 to 3 × 10− 1 s− 1 and temperatures in the range of 573 to 673 K. For microstructural observations, TEM images together with the corresponding SAED patterns were prepared and utilized. A considerable increase in the m-value was observed after the first pass of the operation for all testing temperatures. The best condition for achieving a good superplasticity for the alloy was found to be a single pass DECLE at 673 K in the strain rate range of 10− 2 to 10− 1 s− 1. This process condition resulted in an m-value of 0.43, indicative of a high strain rate superplastic deformation behavior. Further passes of the SPD process did not show any sign of superplasticity until the last pass of the operation, during which the m-value slightly increased, compared with the previous pass.

Materials and Manufacturing Processes, 2013

ABSTRACT This article in concerned with studying the effect of die profile on the load and energy... more ABSTRACT This article in concerned with studying the effect of die profile on the load and energy necessary for plane-strain forward extrusion. With this regard, the geometries of the second-order polynomial and exponential die profiles were optimized in order to minimize the required extrusion pressure calculated based on the slab method. These optimal extrusion dies and the relevant linear one were manufactured for three extrusion ratios. After performing the extrusion experiments, the corresponding finite-element simulations were carried out under the same test conditions. All the analytical, experimental, and numerical findings, which were in good agreement with each other, showed that for all the extrusion ratios, the optimized polynomial and exponential die profiles involved the minimum and maximum force and energy requirements for the process, respectively. Moreover, the influence of the die geometry was more apparent at lower extrusion ratios. When the experimental results were analyzed based on the Taguchi method, it was also found that the effect of the die profile on the maximum extrusion load was more than one third that of the extrusion ratio.

Materials Science and Engineering: A, 2016

This research work is concerned with creation of ZK60 Mg sheets by various combinations of the re... more This research work is concerned with creation of ZK60 Mg sheets by various combinations of the repeated upsetting (RU) and forward extrusion (Ex) operations. The RU process was conducted with different passes and at 250 °C, whereas the subsequent forward extrusion was performed at 220 °C. Complementary tensile tests together with fractography, and microstructural and textural studies were carried out in order to investigate the influence of the process types and conditions on the material properties of the sheet products. It was found that combination of the RU and Ex operations could result in ductile ZK60 sheets with improved strength and strain hardening capacity. The maximum elongation was achieved after 3 passes of RU followed by Ex process. This processing route also resulted in balanced ultimate strengths in both extrusion and transverse directions with almost the highest strain hardening capacity. The effects of RU number of passes and forward extrusion process on the microstructures, textures, mechanical properties and the fracture of the ZK60 sheets were also investigated and, based on the experimental findings obtained; several important conclusions were drawn and explained in this article.

Superplastic behavior of fine and ultra fine-grained AA5083 Al alloy was examined using the shear... more Superplastic behavior of fine and ultra fine-grained AA5083 Al alloy was examined using the shear punch test. To achieve fine-and ultra fine-grained microstructures, a relatively new severe plastic deformation (SPD) process, namely Double Equal Channel Lateral Extrusion (DECLE) was employed. The strain rate sensitivity indices (m) of samples were evaluated after 1, 2, 4, and 6 passes for shear strain rates in the range of 3 × 10 −3 to 3 × 10 −1 s −1 and temperatures in the range of 573 to 673 K. For microstructural observations, TEM images together with the corresponding SAED patterns were prepared and utilized. A considerable increase in the m-value was observed after the first pass of the operation for all testing temperatures. The best condition for achieving a good superplasticity for the alloy was found to be a single pass DECLE at 673 K in the strain rate range of 10 − 2 to 10 − 1 s − 1. This process condition resulted in an m-value of 0.43, indicative of a high strain rate superplastic deformation behavior. Further passes of the SPD process did not show any sign of superplasticity until the last pass of the operation, during which the m-value slightly increased, compared with the previous pass.

Despite valuable electrical characteristics, the use of pure aluminum in different applications h... more Despite valuable electrical characteristics, the use of pure aluminum in different applications has been limited due to its low strength. Non-equal channel angular pressing (NECAP) is a recently proposed severe plastic deformation process with greater induced plastic strain and, consequently, better grain refinement in the product, compared with the well-known equal channel angular pressing technique. This research is concerned with the effects of the process temperature and ram velocity on the mechanical, workability and electrical properties of AA1060 aluminum alloy. Increasing the process temperature can concurrently increase the workability, ductility and electrical conductivity, while it has a reverse influence on the strength of the NECAPed specimen, although the strengths of all the products are higher than the as-received alloy. The influence of the ram speed on the mechanical properties of the processed samples is lower than the process temperature. Finally, a compromised process condition is introduced in order to attain a good combination of workability and strength with well-preserved electrical conductivity for electrical applications of components made of pure aluminum.

Journal of Holistic Nursing and Midwifery, 2009

Medical science experts have reached scientific and technological improvements in recent ‎decades... more Medical science experts have reached scientific and technological improvements in recent ‎decades and have turned surgery into a routine treatment by controlling its complications. ‎Cumulative changes in surgery resulted in decreased pain and discomfort and controlled ‎complications. The developmental path and changes have resulted in endoscopic with minimal ‎invasive surgery (MIS) in which only few small incisions are made on the body and surgery is ‎done through video control which otherwise required more and larger incision with more ‎complication. But this method with all the usefulness has some problems such as discrepancy ‎between surgeon's eye and hand, indirect and two dimensional vision, limited degree of ‎freedom of instruments and surgeon's fatigue. In addition this type of surgery needs complete ‎education and skill. The sum of these factors limits the use of MIS. In order to overcome these ‎problems, robotic surgery method is invented. In this method like MIS, a...

Applied Physics A, 2016

Despite valuable electrical characteristics, the use of pure aluminum in different applications h... more Despite valuable electrical characteristics, the use of pure aluminum in different applications has been limited due to its low strength. Non-equal channel angular pressing (NECAP) is a recently proposed severe plastic deformation process with greater induced plastic strain and, consequently, better grain refinement in the product, compared with the well-known equal channel angular pressing technique. This research is concerned with the effects of the process temperature and ram velocity on the mechanical, workability and electrical properties of AA1060 aluminum alloy. Increasing the process temperature can concurrently increase the workability, ductility and electrical conductivity, while it has a reverse influence on the strength of the NECAPed specimen, although the strengths of all the products are higher than the as-received alloy. The influence of the ram speed on the mechanical properties of the processed samples is lower than the process temperature. Finally, a compromised process condition is introduced in order to attain a good combination of workability and strength with well-preserved electrical conductivity for electrical applications of components made of pure aluminum.

Materials & Design, 2015

Abstract Superplastic behavior of fine and ultra fine-grained AA5083 Al alloy was examined using ... more Abstract Superplastic behavior of fine and ultra fine-grained AA5083 Al alloy was examined using the shear punch test. To achieve fine- and ultra fine-grained microstructures, a relatively new severe plastic deformation (SPD) process, namely Double Equal Channel Lateral Extrusion (DECLE) was employed. The strain rate sensitivity indices (m) of samples were evaluated after 1, 2, 4, and 6 passes for shear strain rates in the range of 3 × 10− 3 to 3 × 10− 1 s− 1 and temperatures in the range of 573 to 673 K. For microstructural observations, TEM images together with the corresponding SAED patterns were prepared and utilized. A considerable increase in the m-value was observed after the first pass of the operation for all testing temperatures. The best condition for achieving a good superplasticity for the alloy was found to be a single pass DECLE at 673 K in the strain rate range of 10− 2 to 10− 1 s− 1. This process condition resulted in an m-value of 0.43, indicative of a high strain rate superplastic deformation behavior. Further passes of the SPD process did not show any sign of superplasticity until the last pass of the operation, during which the m-value slightly increased, compared with the previous pass.

Materials and Manufacturing Processes, 2013

ABSTRACT This article in concerned with studying the effect of die profile on the load and energy... more ABSTRACT This article in concerned with studying the effect of die profile on the load and energy necessary for plane-strain forward extrusion. With this regard, the geometries of the second-order polynomial and exponential die profiles were optimized in order to minimize the required extrusion pressure calculated based on the slab method. These optimal extrusion dies and the relevant linear one were manufactured for three extrusion ratios. After performing the extrusion experiments, the corresponding finite-element simulations were carried out under the same test conditions. All the analytical, experimental, and numerical findings, which were in good agreement with each other, showed that for all the extrusion ratios, the optimized polynomial and exponential die profiles involved the minimum and maximum force and energy requirements for the process, respectively. Moreover, the influence of the die geometry was more apparent at lower extrusion ratios. When the experimental results were analyzed based on the Taguchi method, it was also found that the effect of the die profile on the maximum extrusion load was more than one third that of the extrusion ratio.

Materials Science and Engineering: A, 2016

This research work is concerned with creation of ZK60 Mg sheets by various combinations of the re... more This research work is concerned with creation of ZK60 Mg sheets by various combinations of the repeated upsetting (RU) and forward extrusion (Ex) operations. The RU process was conducted with different passes and at 250 °C, whereas the subsequent forward extrusion was performed at 220 °C. Complementary tensile tests together with fractography, and microstructural and textural studies were carried out in order to investigate the influence of the process types and conditions on the material properties of the sheet products. It was found that combination of the RU and Ex operations could result in ductile ZK60 sheets with improved strength and strain hardening capacity. The maximum elongation was achieved after 3 passes of RU followed by Ex process. This processing route also resulted in balanced ultimate strengths in both extrusion and transverse directions with almost the highest strain hardening capacity. The effects of RU number of passes and forward extrusion process on the microstructures, textures, mechanical properties and the fracture of the ZK60 sheets were also investigated and, based on the experimental findings obtained; several important conclusions were drawn and explained in this article.

Superplastic behavior of fine and ultra fine-grained AA5083 Al alloy was examined using the shear... more Superplastic behavior of fine and ultra fine-grained AA5083 Al alloy was examined using the shear punch test. To achieve fine-and ultra fine-grained microstructures, a relatively new severe plastic deformation (SPD) process, namely Double Equal Channel Lateral Extrusion (DECLE) was employed. The strain rate sensitivity indices (m) of samples were evaluated after 1, 2, 4, and 6 passes for shear strain rates in the range of 3 × 10 −3 to 3 × 10 −1 s −1 and temperatures in the range of 573 to 673 K. For microstructural observations, TEM images together with the corresponding SAED patterns were prepared and utilized. A considerable increase in the m-value was observed after the first pass of the operation for all testing temperatures. The best condition for achieving a good superplasticity for the alloy was found to be a single pass DECLE at 673 K in the strain rate range of 10 − 2 to 10 − 1 s − 1. This process condition resulted in an m-value of 0.43, indicative of a high strain rate superplastic deformation behavior. Further passes of the SPD process did not show any sign of superplasticity until the last pass of the operation, during which the m-value slightly increased, compared with the previous pass.

Despite valuable electrical characteristics, the use of pure aluminum in different applications h... more Despite valuable electrical characteristics, the use of pure aluminum in different applications has been limited due to its low strength. Non-equal channel angular pressing (NECAP) is a recently proposed severe plastic deformation process with greater induced plastic strain and, consequently, better grain refinement in the product, compared with the well-known equal channel angular pressing technique. This research is concerned with the effects of the process temperature and ram velocity on the mechanical, workability and electrical properties of AA1060 aluminum alloy. Increasing the process temperature can concurrently increase the workability, ductility and electrical conductivity, while it has a reverse influence on the strength of the NECAPed specimen, although the strengths of all the products are higher than the as-received alloy. The influence of the ram speed on the mechanical properties of the processed samples is lower than the process temperature. Finally, a compromised process condition is introduced in order to attain a good combination of workability and strength with well-preserved electrical conductivity for electrical applications of components made of pure aluminum.