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Sandeep Kumar - One of the best experts on this subject based on the ideXlab platform.
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Impression creep behaviour of magnesium alloy-based hybrid composites in the Longitudinal Direction
Composites Science and Technology, 2020Co-Authors: A. K. Mondal, Sandeep KumarAbstract:The creep behaviour of a creep-resistant AE42 magnesium alloy reinforced with Saffil short fibres and SiC particulates in various combinations has been examined in the Longitudinal Direction, i.e., the plane containing random fibre orientation was parallel to the loading Direction, in the temperature range of 175-300 C at the stress levels ranging from 60 to 140 MPa using impression creep test technique. At 175 C, normal creep behaviour, i.e., strain rate decreasing with strain and then reaching a steady state, is observed at all the stresses employed. At 240 C, normal creep behaviour is observed up to 80 MPa and reverse creep behaviour, i.e., strain rate increasing with strain, then reaching a steady state and again decreasing, is observed above that stress. At 300 C, reverse creep behaviour is observed at all the stresses employed. This pattern remains the same for all the composites. The reverse creep behaviour is found to be associated with the fibre breakage. The stress exponent is found to be very high for all the composites. However, after taking the threshold stress into account, the stress exponent varies from 3.9 to 7.0, which suggests viscous glide and dislocation climb being the dominant creep mechanisms. The apparent activation energy Qc was not calculated due to insufficient data at any stress level either for normal or reverse creep behaviour. The creep resistance of the hybrid composites is found to be comparable to that of the composite reinforced with 20% Saffil short fibres at all the temperatures and stress levels investigated.Comment: 11 pages, 10 figures. Corrected typographical errors and updated title and conclusion
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dry sliding wear behaviour of magnesium alloy based hybrid composites in the Longitudinal Direction
Wear, 2009Co-Authors: A. K. Mondal, Sandeep KumarAbstract:In the present investigation, the wear behaviour of a creep-resistant AE42 magnesium alloy and its composites reinforced with Saffil short fibres and SiC particles in various combinations is examined in the Longitudinal Direction i.e., the plane containing random fibre orientation is perpendicular to the steel counter-face. Wear tests are conducted on a pin-on-disc set-up under dry sliding condition having a constant sliding velocity of 0.837 m/s for a constant sliding distance of 2.5 km in the load range of 10-40 N. It is observed that the wear rate increases with increase in load for the alloy and the composites, as expected. Wear rate of the composites is lower than the alloy and the hybrid composites exhibit a lower wear rate than the Saffil short fibres reinforced composite at all the loads. Therefore, the partial replacement of Saffil short fibres by an equal volume fraction of SiC particles not only reduces the cost but also improves the wear resistance of the composite. Microstructural investigation of the surface and subsurface of the worn pin and wear debris is carried out to explain the observed results and to understand the wear mechanisms. It is concluded that the presence of SiC particles in the hybrid composites improves the wear resistance because these particles remain intact and retain their load bearing capacity even at the highest load employed, they promote the formation of iron-rich transfer layer and they also delay the fracture of Saffil short fibres to higher loads. Under the experimental conditions used in the present investigation, the dominant wear mechanism is found to be abrasion for the AE42 alloy and its composites. It is accompanied by severe plastic deformation of surface layers in case of alloy and by the fracture of Saffil short fibres as well as the formation of iron-rich transfer layer in case of composites.
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Dry sliding wear behaviour of magnesium alloy based hybrid composites in the Longitudinal Direction
Wear, 2009Co-Authors: A. K. Mondal, Sandeep KumarAbstract:In the present investigation, the wear behaviour of a creep-resistant AE42 magnesium alloy and its composites reinforced with Saffil short fibres and SiC particles in various combinations is examined in the Longitudinal Direction i.e., the plane containing random fibre orientation is perpendicular to the steel counter-face. Wear tests are conducted on a pin-on-disc set-up under dry sliding condition having a constant sliding velocity of 0.837 m/s for a constant sliding distance of 2.5 km in the load range of 10-40 N. It is observed that the wear rate increases with increase in load for the alloy and the composites, as expected. Wear rate of the composites is lower than the alloy and the hybrid composites exhibit a lower wear rate than the Saffil short fibres reinforced composite at all the loads. Therefore, the partial replacement of Saffil short fibres by an equal volume fraction of SiC particles not only reduces the cost but also improves the wear resistance of the composite. Microstructural investigation of the surface and subsurface of the worn pin and wear debris is carried out to explain the observed results and to understand the wear mechanisms. It is concluded that the presence of SiC particles in the hybrid composites improves the wear resistance because these particles remain intact and retain their load bearing capacity even at the highest load employed, they promote the formation of iron-rich transfer layer and they also delay the fracture of Saffil short fibres to higher loads. Under the experimental conditions used in the present investigation, the dominant wear mechanism is found to be abrasion for the AE42 alloy and its composites. It is accompanied by severe plastic deformation of surface layers in case of alloy and by the fracture of Saffil short fibres as well as the formation of iron-rich transfer layer in case of composites. © 2009 Elsevier B.V. All rights reserved.
A. K. Mondal - One of the best experts on this subject based on the ideXlab platform.
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Impression creep behaviour of magnesium alloy-based hybrid composites in the Longitudinal Direction
Composites Science and Technology, 2020Co-Authors: A. K. Mondal, Sandeep KumarAbstract:The creep behaviour of a creep-resistant AE42 magnesium alloy reinforced with Saffil short fibres and SiC particulates in various combinations has been examined in the Longitudinal Direction, i.e., the plane containing random fibre orientation was parallel to the loading Direction, in the temperature range of 175-300 C at the stress levels ranging from 60 to 140 MPa using impression creep test technique. At 175 C, normal creep behaviour, i.e., strain rate decreasing with strain and then reaching a steady state, is observed at all the stresses employed. At 240 C, normal creep behaviour is observed up to 80 MPa and reverse creep behaviour, i.e., strain rate increasing with strain, then reaching a steady state and again decreasing, is observed above that stress. At 300 C, reverse creep behaviour is observed at all the stresses employed. This pattern remains the same for all the composites. The reverse creep behaviour is found to be associated with the fibre breakage. The stress exponent is found to be very high for all the composites. However, after taking the threshold stress into account, the stress exponent varies from 3.9 to 7.0, which suggests viscous glide and dislocation climb being the dominant creep mechanisms. The apparent activation energy Qc was not calculated due to insufficient data at any stress level either for normal or reverse creep behaviour. The creep resistance of the hybrid composites is found to be comparable to that of the composite reinforced with 20% Saffil short fibres at all the temperatures and stress levels investigated.Comment: 11 pages, 10 figures. Corrected typographical errors and updated title and conclusion
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dry sliding wear behaviour of magnesium alloy based hybrid composites in the Longitudinal Direction
Wear, 2009Co-Authors: A. K. Mondal, Sandeep KumarAbstract:In the present investigation, the wear behaviour of a creep-resistant AE42 magnesium alloy and its composites reinforced with Saffil short fibres and SiC particles in various combinations is examined in the Longitudinal Direction i.e., the plane containing random fibre orientation is perpendicular to the steel counter-face. Wear tests are conducted on a pin-on-disc set-up under dry sliding condition having a constant sliding velocity of 0.837 m/s for a constant sliding distance of 2.5 km in the load range of 10-40 N. It is observed that the wear rate increases with increase in load for the alloy and the composites, as expected. Wear rate of the composites is lower than the alloy and the hybrid composites exhibit a lower wear rate than the Saffil short fibres reinforced composite at all the loads. Therefore, the partial replacement of Saffil short fibres by an equal volume fraction of SiC particles not only reduces the cost but also improves the wear resistance of the composite. Microstructural investigation of the surface and subsurface of the worn pin and wear debris is carried out to explain the observed results and to understand the wear mechanisms. It is concluded that the presence of SiC particles in the hybrid composites improves the wear resistance because these particles remain intact and retain their load bearing capacity even at the highest load employed, they promote the formation of iron-rich transfer layer and they also delay the fracture of Saffil short fibres to higher loads. Under the experimental conditions used in the present investigation, the dominant wear mechanism is found to be abrasion for the AE42 alloy and its composites. It is accompanied by severe plastic deformation of surface layers in case of alloy and by the fracture of Saffil short fibres as well as the formation of iron-rich transfer layer in case of composites.
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Dry sliding wear behaviour of magnesium alloy based hybrid composites in the Longitudinal Direction
Wear, 2009Co-Authors: A. K. Mondal, Sandeep KumarAbstract:In the present investigation, the wear behaviour of a creep-resistant AE42 magnesium alloy and its composites reinforced with Saffil short fibres and SiC particles in various combinations is examined in the Longitudinal Direction i.e., the plane containing random fibre orientation is perpendicular to the steel counter-face. Wear tests are conducted on a pin-on-disc set-up under dry sliding condition having a constant sliding velocity of 0.837 m/s for a constant sliding distance of 2.5 km in the load range of 10-40 N. It is observed that the wear rate increases with increase in load for the alloy and the composites, as expected. Wear rate of the composites is lower than the alloy and the hybrid composites exhibit a lower wear rate than the Saffil short fibres reinforced composite at all the loads. Therefore, the partial replacement of Saffil short fibres by an equal volume fraction of SiC particles not only reduces the cost but also improves the wear resistance of the composite. Microstructural investigation of the surface and subsurface of the worn pin and wear debris is carried out to explain the observed results and to understand the wear mechanisms. It is concluded that the presence of SiC particles in the hybrid composites improves the wear resistance because these particles remain intact and retain their load bearing capacity even at the highest load employed, they promote the formation of iron-rich transfer layer and they also delay the fracture of Saffil short fibres to higher loads. Under the experimental conditions used in the present investigation, the dominant wear mechanism is found to be abrasion for the AE42 alloy and its composites. It is accompanied by severe plastic deformation of surface layers in case of alloy and by the fracture of Saffil short fibres as well as the formation of iron-rich transfer layer in case of composites. © 2009 Elsevier B.V. All rights reserved.
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Impression creep behaviour of magnesium alloy-based hybrid composites in the Longitudinal Direction
Composites Science and Technology, 2008Co-Authors: A. K. Mondal, Sanjeev KumarAbstract:Abstract The creep behaviour of a creep-resistant AE42 magnesium alloy reinforced with Saffil short fibres and SiC particulates in various combinations has been examined in the Longitudinal Direction, i.e., the plane containing random fibre orientation was parallel to the loading Direction, in the temperature range of 175–300 °C at the stress levels ranging from 60 to 140 MPa using impression creep test technique. At 175 °C, normal creep behaviour, i.e., strain rate decreasing with strain and then reaching a steady state, is observed at all the stresses employed. At 240 °C, normal creep behaviour is observed up to 80 MPa and reverse creep behaviour, i.e., strain rate increasing with strain, then reaching a steady state and again decreasing, is observed above that stress. At 300 °C, reverse creep behaviour is observed at all the stresses employed. This pattern remains the same for all the composites. The reverse creep behaviour is found to be associated with the fibre breakage. The stress exponent is found to be very high for all the composites. However, after taking the threshold stress into account, the stress exponent varies from 3.9 to 7.0, which suggests viscous glide and dislocation climb being the dominant creep mechanisms. The apparent activation energy Qc was not calculated due to insufficient data at any stress level either for normal or reverse creep behaviour. The creep resistance of the hybrid composites is found to be comparable to that of the composite reinforced with 20% Saffil short fibres at all the temperatures and stress levels investigated.
Christine T. Chevalier - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of Double Exponentially Tapered Slot Antenna (DETSA) Conformed in the Longitudinal Direction Around a Cylindrical Structure
2020Co-Authors: George E. Ponchak, J.l. Jordan, Christine T. ChevalierAbstract:The chamcterislics of a double exponentially ta~ered slot antenna (DETSAI as a function ofthe radius that the DETSA is conformed'to in th; Longitudinal Direction is presented. It is shown through measurements and simulations that the radiation pattern of the conformed antenna rotates in the Direction through which the antenna is curved, and that diffraction affects the radiation pattern if the radius of curvature is too small or the frequency too high. The gain of the antenna degrades by only 1 dB if the radius of curvature is large and more than 2 dB for smaller radii. The main effect due to curving the antenna is an increased cross-polarization in the E-plane. TSA around a foam cylinder with the discontinuity in the transverse and Longitudinal Direction is presented. Only the effect on gain is described, with no discussion of the radiation pattern. A Double Exponentially Tapered Slot Antenna (DETSA), a variation of the Vivaldi Antenna, designed for Ultra Wide Band (UWB) applications conformed over a gently rounded foam shape in the longihldial Direction is described in (6). It was shown that the main beam is skewed towards the Direction of curvature. However, there has not been an in depth exploration on the effect of conforming a TSA around a curved structure. In this paper, experimental and simulated characteristics of a DETSA designed for 3 to 10 GHz and conformed in the Longitudinal Direction around cylindrical, foam structures is presented. The gain, 3dB beamwidth, cross polarization level, and beam Direction are presented for different cylinder radii.
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Characteristics of Double Exponentially Tapered Slot Antenna (DETSA) Conformed in the Longitudinal Direction Around a Cylinder
IEEE Antennas and Wireless Propagation Letters, 2007Co-Authors: George E. Ponchak, J.l. Jordan, Christine T. ChevalierAbstract:The characteristics of a double exponentially tapered slot antenna (DETSA) as a function of the radius that the DETSA is conformed to in the Longitudinal Direction is presented. It is shown through measurements and simulations that the radiation pattern of the conformed antenna rotates in the Direction through which the antenna is curved, and that diffraction affects the radiation pattern if the radius of curvature is too small or the frequency too high. The gain of the antenna degrades by only 1 dB if the radius of curvature is large and more than 2 dB for smaller radii. The main effect due to curving the antenna is an increased cross polarization in the E-plane
George E. Ponchak - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of Double Exponentially Tapered Slot Antenna (DETSA) Conformed in the Longitudinal Direction Around a Cylindrical Structure
2020Co-Authors: George E. Ponchak, J.l. Jordan, Christine T. ChevalierAbstract:The chamcterislics of a double exponentially ta~ered slot antenna (DETSAI as a function ofthe radius that the DETSA is conformed'to in th; Longitudinal Direction is presented. It is shown through measurements and simulations that the radiation pattern of the conformed antenna rotates in the Direction through which the antenna is curved, and that diffraction affects the radiation pattern if the radius of curvature is too small or the frequency too high. The gain of the antenna degrades by only 1 dB if the radius of curvature is large and more than 2 dB for smaller radii. The main effect due to curving the antenna is an increased cross-polarization in the E-plane. TSA around a foam cylinder with the discontinuity in the transverse and Longitudinal Direction is presented. Only the effect on gain is described, with no discussion of the radiation pattern. A Double Exponentially Tapered Slot Antenna (DETSA), a variation of the Vivaldi Antenna, designed for Ultra Wide Band (UWB) applications conformed over a gently rounded foam shape in the longihldial Direction is described in (6). It was shown that the main beam is skewed towards the Direction of curvature. However, there has not been an in depth exploration on the effect of conforming a TSA around a curved structure. In this paper, experimental and simulated characteristics of a DETSA designed for 3 to 10 GHz and conformed in the Longitudinal Direction around cylindrical, foam structures is presented. The gain, 3dB beamwidth, cross polarization level, and beam Direction are presented for different cylinder radii.
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Characteristics of Double Exponentially Tapered Slot Antenna (DETSA) Conformed in the Longitudinal Direction Around a Cylinder
IEEE Antennas and Wireless Propagation Letters, 2007Co-Authors: George E. Ponchak, J.l. Jordan, Christine T. ChevalierAbstract:The characteristics of a double exponentially tapered slot antenna (DETSA) as a function of the radius that the DETSA is conformed to in the Longitudinal Direction is presented. It is shown through measurements and simulations that the radiation pattern of the conformed antenna rotates in the Direction through which the antenna is curved, and that diffraction affects the radiation pattern if the radius of curvature is too small or the frequency too high. The gain of the antenna degrades by only 1 dB if the radius of curvature is large and more than 2 dB for smaller radii. The main effect due to curving the antenna is an increased cross polarization in the E-plane
J.l. Jordan - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of Double Exponentially Tapered Slot Antenna (DETSA) Conformed in the Longitudinal Direction Around a Cylindrical Structure
2020Co-Authors: George E. Ponchak, J.l. Jordan, Christine T. ChevalierAbstract:The chamcterislics of a double exponentially ta~ered slot antenna (DETSAI as a function ofthe radius that the DETSA is conformed'to in th; Longitudinal Direction is presented. It is shown through measurements and simulations that the radiation pattern of the conformed antenna rotates in the Direction through which the antenna is curved, and that diffraction affects the radiation pattern if the radius of curvature is too small or the frequency too high. The gain of the antenna degrades by only 1 dB if the radius of curvature is large and more than 2 dB for smaller radii. The main effect due to curving the antenna is an increased cross-polarization in the E-plane. TSA around a foam cylinder with the discontinuity in the transverse and Longitudinal Direction is presented. Only the effect on gain is described, with no discussion of the radiation pattern. A Double Exponentially Tapered Slot Antenna (DETSA), a variation of the Vivaldi Antenna, designed for Ultra Wide Band (UWB) applications conformed over a gently rounded foam shape in the longihldial Direction is described in (6). It was shown that the main beam is skewed towards the Direction of curvature. However, there has not been an in depth exploration on the effect of conforming a TSA around a curved structure. In this paper, experimental and simulated characteristics of a DETSA designed for 3 to 10 GHz and conformed in the Longitudinal Direction around cylindrical, foam structures is presented. The gain, 3dB beamwidth, cross polarization level, and beam Direction are presented for different cylinder radii.
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Characteristics of Double Exponentially Tapered Slot Antenna (DETSA) Conformed in the Longitudinal Direction Around a Cylinder
IEEE Antennas and Wireless Propagation Letters, 2007Co-Authors: George E. Ponchak, J.l. Jordan, Christine T. ChevalierAbstract:The characteristics of a double exponentially tapered slot antenna (DETSA) as a function of the radius that the DETSA is conformed to in the Longitudinal Direction is presented. It is shown through measurements and simulations that the radiation pattern of the conformed antenna rotates in the Direction through which the antenna is curved, and that diffraction affects the radiation pattern if the radius of curvature is too small or the frequency too high. The gain of the antenna degrades by only 1 dB if the radius of curvature is large and more than 2 dB for smaller radii. The main effect due to curving the antenna is an increased cross polarization in the E-plane
