The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
B S Yilbas - One of the best experts on this subject based on the ideXlab platform.
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laser cutting of small Diameter Hole in aluminum foam
The International Journal of Advanced Manufacturing Technology, 2015Co-Authors: B S Yilbas, S S Akhtar, Omer KelesAbstract:Laser cutting of a small Diameter Hole into alumi- num foam is carried out, and thermal stress field developed in the cutting section is examined incorporating the finite ele- ment code. Laser cutting experiments are conducted to exam- ine the morphological changes in the cut sections through using scanning electron microscope, energy-dispersive spec- troscopy, and X-ray diffraction. It is found that von Mises stress attains high values in the region where the temperature gradient is high. The slow cooling of the last cut region in the Hole circumference suppresses the stress level in this region. Holes cut are parallel sided and free from defects such as sideway burning and large burr formation.
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LASER CUTTING OF LARGE Diameter HoleS INTO ALUMINUM FOAM
Machining Science and Technology, 2013Co-Authors: B S Yilbas, Sohail Akhtar, Omer KelesAbstract:Laser cutting of large Diameter Hole in aluminum foam is carried out and morphological changes in the cutting section are examined using scanning electron microscopes, energy dispersive spectroscopy and X-ray diffraction. The thermal stress fields in the cutting section are computed in line with the experimental conditions. Finite element code is incorporated in the numerical simulations. It is found that the cut section is free from defects such as large size burrs and dross attachments. The thermal stress predicted is less than the yielding limit of the workpiece. The presence of air trapped within the pores prior to laser irradiation in the workpiece results in the formation of oxide compounds at the cut sections.
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laser Hole cutting in aluminum foam influence of Hole Diameter on thermal stress
Optics and Lasers in Engineering, 2013Co-Authors: B S Yilbas, S S Akhtar, Omer KelesAbstract:Laser cutting of aluminum foams avoids structural damages, which can be observed during mechanical cutting process. High thermal stresses can be formed in the laser cut sections due to high temperature gradients while limiting the practical applications of parts. In the present study, laser cutting of 2 mm and 8 mm Diameter Holes into aluminum foam is carried out. Geometrical changes in the cut section are examined using optical and scanning electron microscopes and oxide compounds formed at the kerf surface are identified by X-ray diffraction. Temperature and stress fields are predicted numerically in the cut section in the line with the experimental conditions. It is found that defect free cutting of small Diameter Holes is possible in 8 mm thick aluminum foam. Air trapped in the pores prior to laser cutting undergoes oxidation reactions with molten material while resulting in forming of Al2O3 and AlO compounds at the cut surfaces. von Mises stress predicted for 2 mm Diameter Hole is almost 3 times higher than that corresponding to 8 m Diameter Hole.
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laser trepanning of a small Diameter Hole in titanium alloy temperature and stress fields
Journal of Materials Processing Technology, 2011Co-Authors: B S Yilbas, S S Akhtar, C KaratasAbstract:High stresses formed around the laser cut edges limit the practical applications of the parts produced. In the present study, laser cutting of small Diameter Hole into Ti–6Al–4V alloy is carried out. Temperature and stress fields developed in the cutting region are simulated, in line with the experimental parameters, via incorporating the finite element code. The temperature predictions are validated with the thermocouple data. The residual stress developed at the vicinity of the cut surface is obtained using the XRD technique. The features of the Hole section are examined using the optical and scanning electron microscopes. It is found that temperature decay is gradual, due to the annealing effect, in the region where the cutting ends; in which case, the peak value of von Mises stress reduces in this region. The residual stress predicted agrees well with the data obtained from the XRD technique.
C Karatas - One of the best experts on this subject based on the ideXlab platform.
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laser trepanning of a small Diameter Hole in titanium alloy temperature and stress fields
Journal of Materials Processing Technology, 2011Co-Authors: B S Yilbas, S S Akhtar, C KaratasAbstract:High stresses formed around the laser cut edges limit the practical applications of the parts produced. In the present study, laser cutting of small Diameter Hole into Ti–6Al–4V alloy is carried out. Temperature and stress fields developed in the cutting region are simulated, in line with the experimental parameters, via incorporating the finite element code. The temperature predictions are validated with the thermocouple data. The residual stress developed at the vicinity of the cut surface is obtained using the XRD technique. The features of the Hole section are examined using the optical and scanning electron microscopes. It is found that temperature decay is gradual, due to the annealing effect, in the region where the cutting ends; in which case, the peak value of von Mises stress reduces in this region. The residual stress predicted agrees well with the data obtained from the XRD technique.
S S Akhtar - One of the best experts on this subject based on the ideXlab platform.
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laser cutting of small Diameter Hole in aluminum foam
The International Journal of Advanced Manufacturing Technology, 2015Co-Authors: B S Yilbas, S S Akhtar, Omer KelesAbstract:Laser cutting of a small Diameter Hole into alumi- num foam is carried out, and thermal stress field developed in the cutting section is examined incorporating the finite ele- ment code. Laser cutting experiments are conducted to exam- ine the morphological changes in the cut sections through using scanning electron microscope, energy-dispersive spec- troscopy, and X-ray diffraction. It is found that von Mises stress attains high values in the region where the temperature gradient is high. The slow cooling of the last cut region in the Hole circumference suppresses the stress level in this region. Holes cut are parallel sided and free from defects such as sideway burning and large burr formation.
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laser Hole cutting in aluminum foam influence of Hole Diameter on thermal stress
Optics and Lasers in Engineering, 2013Co-Authors: B S Yilbas, S S Akhtar, Omer KelesAbstract:Laser cutting of aluminum foams avoids structural damages, which can be observed during mechanical cutting process. High thermal stresses can be formed in the laser cut sections due to high temperature gradients while limiting the practical applications of parts. In the present study, laser cutting of 2 mm and 8 mm Diameter Holes into aluminum foam is carried out. Geometrical changes in the cut section are examined using optical and scanning electron microscopes and oxide compounds formed at the kerf surface are identified by X-ray diffraction. Temperature and stress fields are predicted numerically in the cut section in the line with the experimental conditions. It is found that defect free cutting of small Diameter Holes is possible in 8 mm thick aluminum foam. Air trapped in the pores prior to laser cutting undergoes oxidation reactions with molten material while resulting in forming of Al2O3 and AlO compounds at the cut surfaces. von Mises stress predicted for 2 mm Diameter Hole is almost 3 times higher than that corresponding to 8 m Diameter Hole.
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laser trepanning of a small Diameter Hole in titanium alloy temperature and stress fields
Journal of Materials Processing Technology, 2011Co-Authors: B S Yilbas, S S Akhtar, C KaratasAbstract:High stresses formed around the laser cut edges limit the practical applications of the parts produced. In the present study, laser cutting of small Diameter Hole into Ti–6Al–4V alloy is carried out. Temperature and stress fields developed in the cutting region are simulated, in line with the experimental parameters, via incorporating the finite element code. The temperature predictions are validated with the thermocouple data. The residual stress developed at the vicinity of the cut surface is obtained using the XRD technique. The features of the Hole section are examined using the optical and scanning electron microscopes. It is found that temperature decay is gradual, due to the annealing effect, in the region where the cutting ends; in which case, the peak value of von Mises stress reduces in this region. The residual stress predicted agrees well with the data obtained from the XRD technique.
Omer Keles - One of the best experts on this subject based on the ideXlab platform.
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laser cutting of small Diameter Hole in aluminum foam
The International Journal of Advanced Manufacturing Technology, 2015Co-Authors: B S Yilbas, S S Akhtar, Omer KelesAbstract:Laser cutting of a small Diameter Hole into alumi- num foam is carried out, and thermal stress field developed in the cutting section is examined incorporating the finite ele- ment code. Laser cutting experiments are conducted to exam- ine the morphological changes in the cut sections through using scanning electron microscope, energy-dispersive spec- troscopy, and X-ray diffraction. It is found that von Mises stress attains high values in the region where the temperature gradient is high. The slow cooling of the last cut region in the Hole circumference suppresses the stress level in this region. Holes cut are parallel sided and free from defects such as sideway burning and large burr formation.
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LASER CUTTING OF LARGE Diameter HoleS INTO ALUMINUM FOAM
Machining Science and Technology, 2013Co-Authors: B S Yilbas, Sohail Akhtar, Omer KelesAbstract:Laser cutting of large Diameter Hole in aluminum foam is carried out and morphological changes in the cutting section are examined using scanning electron microscopes, energy dispersive spectroscopy and X-ray diffraction. The thermal stress fields in the cutting section are computed in line with the experimental conditions. Finite element code is incorporated in the numerical simulations. It is found that the cut section is free from defects such as large size burrs and dross attachments. The thermal stress predicted is less than the yielding limit of the workpiece. The presence of air trapped within the pores prior to laser irradiation in the workpiece results in the formation of oxide compounds at the cut sections.
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laser Hole cutting in aluminum foam influence of Hole Diameter on thermal stress
Optics and Lasers in Engineering, 2013Co-Authors: B S Yilbas, S S Akhtar, Omer KelesAbstract:Laser cutting of aluminum foams avoids structural damages, which can be observed during mechanical cutting process. High thermal stresses can be formed in the laser cut sections due to high temperature gradients while limiting the practical applications of parts. In the present study, laser cutting of 2 mm and 8 mm Diameter Holes into aluminum foam is carried out. Geometrical changes in the cut section are examined using optical and scanning electron microscopes and oxide compounds formed at the kerf surface are identified by X-ray diffraction. Temperature and stress fields are predicted numerically in the cut section in the line with the experimental conditions. It is found that defect free cutting of small Diameter Holes is possible in 8 mm thick aluminum foam. Air trapped in the pores prior to laser cutting undergoes oxidation reactions with molten material while resulting in forming of Al2O3 and AlO compounds at the cut surfaces. von Mises stress predicted for 2 mm Diameter Hole is almost 3 times higher than that corresponding to 8 m Diameter Hole.
Ken Takeuchi - One of the best experts on this subject based on the ideXlab platform.
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Control gate length, spacing, channel Hole Diameter, and stacked layer number design for bit-cost scalable-type three-dimensional stackable NAND flash memory
Japanese Journal of Applied Physics, 2014Co-Authors: Kousuke Miyaji, Yuki Yanagihara, Reo Hirasawa, Sheyang Ning, Ken TakeuchiAbstract:A cell design for three-dimensional (3D) stackable NAND (3D NAND) flash memory are investigated with emphases on control gate length (Lg), spacing (Lspace) and channel Hole Diameter (Φ). The requirements for the Lg and Lspace are derived from the 3D device simulation and the effective cell size that competes with the planar NAND. The simulations reveal that Lg = Lspace = 20 nm (40 nm layer pitch) is achievable for bit-cost scalable (BiCS)-type 3D NAND with the 90 nm Diameter Hole. If the number of stacked layers is 22 with the layer pitch of 40 nm, the effective cell size of the 3D NAND corresponds to that of 15 nm planar NAND technology. Furthermore, cell characteristics of the macaroni body channel with various Φ are investigated. Although macaroni body channel improves cell characteristics at Φ = 90 nm, a cell with Φ = 60 nm without macaroni body structure shows better characteristics.
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Control Gate Length, Spacing and Stacked Layer Number Design for 3D-Stackable NAND Flash Memory
2012 4th IEEE International Memory Workshop, 2012Co-Authors: Yuki Yanagihara, Kousuke Miyaji, Ken TakeuchiAbstract:Scaling and device design for 3D-stackable NAND (3D NAND) flash memory are investigated. Control gate length (Lg) and spacing (Lspace) are paid attention since they can be separately varied in 3D NAND and significantly affect the cell area of the 3D NAND as well as the electrical characteristics. The requirements for the Lg and Lspace are derived from the 3D device simulation and the cell size to compete with the planar NAND. The simulations reveal that Lg=Lspace=20nm (40nm layer pitch) is achievable for BiCS type 3D NAND with the 90nm Diameter Hole. Programming voltage can be also reduced from 20V to 17V. Lg and Lspace should be the same to cope with the tradeoff between memory window and disturbance. If the number of stacked layers is 18 with the layer pitch of 40nm, the effective cell size of the 3D NAND corresponds to that of 15nm planar NAND technology.