The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Mahmoud Ebrahimi - One of the best experts on this subject based on the ideXlab platform.
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A novel technique to increase Strain Distribution homogeneity for ECAPed
2020Co-Authors: Faramarz Djavanroodi, M. Daneshtalab, Mahmoud EbrahimiAbstract:a b s t r a c t Equal channel angular pressing as a material processing technique imposes high but in-homogeneous Strain at the cross-section of the workpiece. In this research, cylindrical shaped commercial pure aluminum undergoes ECAP process up to four passes by route A using the conventional and covered tube casing (CTC) methods. The influence of CTC on Strain Distribution in the region of uniform longitudinal Strain field was investigated experimentally and numerically. The Vickers hardness measurement at the cross-section of the aluminum samples indicated that there is more uniformity in the deformation during a single-pass ECAP in the CTC method compared with the conventional method and matched the simulated effective Strain Distributions. Moreover, based on volume fraction rule, an analysis has been developed to predict the required pressing force for CTC method.
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designing of ecap parameters based on Strain Distribution uniformity
Progress in Natural Science: Materials International, 2012Co-Authors: F Djavanroodi, B Omranpour, Mahmoud Ebrahimi, M SedighiAbstract:Abstract Equal Channel Angular Pressing (ECAP) is currently one of the most popular methods for fabricating Ultra-Fine Grained (UFG) materials. In this work, ECAP process has been performed on commercial pure aluminum up to 8 passes by route A . After verification of FEM work, the influences of four die channel angles, three outer corner angles and pass number up to 8 have been analyzed to investigate Strain Distribution behavior of ECAPed material. Two methods for quantifying the Strain homogeneity namely inhomogeneity index ( C i ) and standard deviation (S.D.) are compared. It is shown that C i is not a good candidate for examining the Strain Distribution uniformity. Moreover, it is suggested that designing of ECAP die geometry to achieve optimum Strain Distribution homogeneity is more suitable than the optimum effective Strain magnitude. The best Strain Distribution uniformity in the transverse plane is obtained with Φ =60° and Ψ =15° and for the bulk of the sample, Φ =120° and Ψ =15° or 60°, gives the highest Strain dispersal uniformity.
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a novel technique to increase Strain Distribution homogeneity for ecaped materials
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: F Djavanroodi, M. Daneshtalab, Mahmoud EbrahimiAbstract:Abstract Equal channel angular pressing as a material processing technique imposes high but in-homogeneous Strain at the cross-section of the workpiece. In this research, cylindrical shaped commercial pure aluminum undergoes ECAP process up to four passes by route A using the conventional and covered tube casing (CTC) methods. The influence of CTC on Strain Distribution in the region of uniform longitudinal Strain field was investigated experimentally and numerically. The Vickers hardness measurement at the cross-section of the aluminum samples indicated that there is more uniformity in the deformation during a single-pass ECAP in the CTC method compared with the conventional method and matched the simulated effective Strain Distributions. Moreover, based on volume fraction rule, an analysis has been developed to predict the required pressing force for CTC method.
Masao Toyoda - One of the best experts on this subject based on the ideXlab platform.
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Analytical Study on Effects of Strain Distribution in Welding Start/End on Welding Distortion
Quarterly Journal of The Japan Welding Society, 2020Co-Authors: Masahito Mochizuki, Yoshiki Mikami, Hiroki Yamasaki, Masao ToyodaAbstract:A welding distortion prediction method based on inherent Strain concept was presented. In the proposed method, welding distortion of large welded structures could be estimated by elastic analysis using the result of thermal-elastic-plastic analysis result of smaller welded joints or components. Thermal-elastic-plastic analysis is performed to calculate residual plastic Strain Distribution, which is the input data for the elastic analysis of welding distortion. The obtained residual plastic Strain Distribution is mapped to non-deformed finite element models to calculate welding distortion by elastic analysis. The mapping procedure is done in different ways for welding start/end parts and the rest of weld length in order to take into consideration of unsteady Strain Distribution at start/end of welds. For start/end parts, Strain Distribution used is identical with thermal-elastic-plastic analysis. For the part except start/end parts, Strain Distribution obtained by thermal-elastic-plastic analysis is extracted from the center of weld length and is extruded along welding direction. The proposed method was applied to the welding distortion prediction of joints with weld length 900 mm and 1200 mm based on thermal-elastic-plastic analysis result of a joint with weld length 600 mm. The estimated results were in good agreement with the thermal-elastic-plastic analysis results of models of corresponding weld length to show the validity of the proposed method.
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Analytical study on effects of Strain Distribution in welding start/end on welding distortion
Welding International, 2009Co-Authors: Masahito Mochizuki, Yoshiki Mikami, Hiroki Yamasaki, Masao ToyodaAbstract:A welding distortion prediction method based on the inherent Strain concept is presented. In the proposed method, welding distortion of large-welded structures could be estimated by elastic analysis using the result of thermal-elastic–plastic analysis and the result of smaller welded joints or components. Thermal-elastic–plastic analysis is performed to calculate residual plastic Strain Distribution, which is the input data for the elastic analysis of welding distortion. The obtained residual plastic Strain Distribution is mapped to non-deformed finite element models to calculate welding distortion by elastic analysis. The mapping procedure is done in different ways for welding start/end parts and the rest of the weld length in order to take into consideration the unsteady Strain Distribution at the start/end of welds. For start/end parts, Strain Distribution used is identical with thermal-elastic–plastic analysis. For the part except start/end parts, Strain Distribution obtained by thermal-elastic–plasti...
Kazumi Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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analysis and design of a tactile sensor detecting Strain Distribution inside an elastic finger
Intelligent Robots and Systems, 1998Co-Authors: Takashi Maeno, T Kawai, Kazumi KobayashiAbstract:Humans obtain complex information using different tactile receptors in the skin of the finger. Artificial tactile sensors capable of detecting complex information can be realized by imitating certain characteristics of the human finger, such as the geometry of the finger and the location of the tactile receptors. We analyze the Strain Distribution that occurs inside an elastic finger having a curved surface when the finger is in contact with an object. Detection of the shear Strain Distribution pattern is found to be important. In addition a Strain Distribution sensor is developed, in which Strain gages bonded on thin plates are arranged at uniform intervals inside the curved surface of an elastic finger made of silicone rubber. The geometry of the elastic finger is designed by calculating the contact condition between the finger and objects with/without tangential load using FE (finite element) analysis. The fundamental characteristics of the Strain Distribution sensor are confirmed.
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IROS - Analysis and design of a tactile sensor detecting Strain Distribution inside an elastic finger
Proceedings. 1998 IEEE RSJ International Conference on Intelligent Robots and Systems. Innovations in Theory Practice and Applications (Cat. No.98CH36, 1998Co-Authors: Takashi Maeno, T Kawai, Kazumi KobayashiAbstract:Humans obtain complex information using different tactile receptors in the skin of the finger. Artificial tactile sensors capable of detecting complex information can be realized by imitating certain characteristics of the human finger, such as the geometry of the finger and the location of the tactile receptors. We analyze the Strain Distribution that occurs inside an elastic finger having a curved surface when the finger is in contact with an object. Detection of the shear Strain Distribution pattern is found to be important. In addition a Strain Distribution sensor is developed, in which Strain gages bonded on thin plates are arranged at uniform intervals inside the curved surface of an elastic finger made of silicone rubber. The geometry of the elastic finger is designed by calculating the contact condition between the finger and objects with/without tangential load using FE (finite element) analysis. The fundamental characteristics of the Strain Distribution sensor are confirmed.
F Djavanroodi - One of the best experts on this subject based on the ideXlab platform.
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designing of ecap parameters based on Strain Distribution uniformity
Progress in Natural Science: Materials International, 2012Co-Authors: F Djavanroodi, B Omranpour, Mahmoud Ebrahimi, M SedighiAbstract:Abstract Equal Channel Angular Pressing (ECAP) is currently one of the most popular methods for fabricating Ultra-Fine Grained (UFG) materials. In this work, ECAP process has been performed on commercial pure aluminum up to 8 passes by route A . After verification of FEM work, the influences of four die channel angles, three outer corner angles and pass number up to 8 have been analyzed to investigate Strain Distribution behavior of ECAPed material. Two methods for quantifying the Strain homogeneity namely inhomogeneity index ( C i ) and standard deviation (S.D.) are compared. It is shown that C i is not a good candidate for examining the Strain Distribution uniformity. Moreover, it is suggested that designing of ECAP die geometry to achieve optimum Strain Distribution homogeneity is more suitable than the optimum effective Strain magnitude. The best Strain Distribution uniformity in the transverse plane is obtained with Φ =60° and Ψ =15° and for the bulk of the sample, Φ =120° and Ψ =15° or 60°, gives the highest Strain dispersal uniformity.
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a novel technique to increase Strain Distribution homogeneity for ecaped materials
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: F Djavanroodi, M. Daneshtalab, Mahmoud EbrahimiAbstract:Abstract Equal channel angular pressing as a material processing technique imposes high but in-homogeneous Strain at the cross-section of the workpiece. In this research, cylindrical shaped commercial pure aluminum undergoes ECAP process up to four passes by route A using the conventional and covered tube casing (CTC) methods. The influence of CTC on Strain Distribution in the region of uniform longitudinal Strain field was investigated experimentally and numerically. The Vickers hardness measurement at the cross-section of the aluminum samples indicated that there is more uniformity in the deformation during a single-pass ECAP in the CTC method compared with the conventional method and matched the simulated effective Strain Distributions. Moreover, based on volume fraction rule, an analysis has been developed to predict the required pressing force for CTC method.
Hiroshi Naruse - One of the best experts on this subject based on the ideXlab platform.
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shape variation of brillouin gain spectrum caused by sinusoidal like Strain Distribution
Conference on Lasers and Electro-Optics, 2013Co-Authors: Yoshiki Hayase, Hiroshi NaruseAbstract:Shape variation characteristics of the Brillouin gain spectrum caused by sinusoidal-like Strain Distribution, which is a typical non-uniform Strain Distribution produced in a ring structure, are clarified through numerical calculation and experiments.
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Deformation of Brillouin scattered light power spectrum shape by linear Strain Distribution
20th International Conference on Optical Fibre Sensors, 2009Co-Authors: Kei Yasuda, Hiroshi Naruse, Che-hsien Li, Masafumi TatedaAbstract:A number of distributed fiber optic Strain sensing systems are proposed that are based on the frequency shift of the Brillouin scattered light power spectrum in proportion to the Strain produced in the fiber. Although the spectral shape under a uniform Strain Distribution is generally given by a Lorentzian function, it is deformed under a non-uniform Strain Distribution. It is important to investigate the relationship between the non-uniform Strain Distribution and the spectral deformation, because it affects the Strain measurement error. We have focused on a linear Strain Distribution where the Strain changes at a constant rate along the fiber as a typical non-uniform Strain Distribution. The power spectrum shape is derived theoretically using the Brillouin frequency shift values at the both ends of the observation section. The power spectrum of the Brillouin scattered light is then observed experimentally. The experimentally observed power spectrum shape was in good agreement with that theoretically obtained and the power spectrum was widened according to the slope of the linear Strain Distribution.
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dependence of the brillouin gain spectrum on linear Strain Distribution for optical time domain reflectometer type Strain sensors
Applied Optics, 2002Co-Authors: Hiroshi Naruse, Hiroshige Ohno, Masafumi Tateda, Akiyoshi ShimadaAbstract:We theoretically derive the shape of the Brillouin gain spectrum, that is, the Brillouin backscattered-light power spectrum, produced in an optical fiber under conditions of a Strain Distribution that changes linearly with a constant slope. The modeled measurement system is an optical time-domain reflectometer-type Strain sensor system. The linear Strain Distribution is one of the fundamental Distributions and is produced in, for example, a beam to which a concentrated load is applied. By analyzing a function that expresses the shape of the derived Brillouin gain spectrum, we show that the Strain calculated from the frequency at which the spectrum has a peak value coincides with that at the center of the effective pulsed light. In addition, the peak value and the full width at half-maximum of the Brillouin gain spectrum are both influenced by the Strain difference between the two ends of the effective pulse. We investigate this influence in detail and obtain the relationship between Strain difference and Strain measurement error.
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Linear Strain Distribution dependence of the Brillouin gain spectrum
2002 15th Optical Fiber Sensors Conference Technical Digest. OFS 2002(Cat. No.02EX533), 2002Co-Authors: Hiroshi Naruse, Hiroshige Ohno, Masafumi Tateda, Akiyoshi ShimadaAbstract:We undertook a theoretical study of the Brillouin gain spectrum dependence on the Strain Distribution in an optical fiber, which changes linearly with a constant slope. We also investigated the Strain measurement error in BOTDR induced by the linear Strain Distribution.
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Linear Strain Distribution dependence of the Brillouin gain spectrum
2002 15th Optical Fiber Sensors Conference Technical Digest OFS 2002, 2002Co-Authors: Hiroshi Naruse, Hiroshige Ohno, Masafumi Tateda, Akiyoshi ShimadaAbstract:We theoretically derive the shape of the Brillouin gain spectrum, that is, the Briilouin backscattered-light power spectrum produced in an optical fiber under conditions of a Strain Distribution that changes linearly with a constant slope. The modeled measurement system is an optical time-domain reflectometer-type Strain sensor system. The linear Strain Distribution is one of the fundamental Distributions and is produced in, for example, a beam to which a concentrated load is applied. By analyzing a function that expresses the shape of the derived Brillouin gain spectrum, we show that the Strain calculated from the frequency at which the spectrum has a peek value coincide. with that at the center of the effective pulsed light. In addition, the peak value and the full width at half maximum of the Brillouin gain spectrum are both influenced by the Strain difference between the two ends of the effective pulse. We investigate this influence in detail and obtain the relationship between Strain difference and Strain measurement error.
