The Experts below are selected from a list of 9222 Experts worldwide ranked by ideXlab platform
Toshihiko Kuwabara - One of the best experts on this subject based on the ideXlab platform.
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Biaxial Stress Testing Methods for Sheet Metals
Comprehensive Materials Processing, 2014Co-Authors: Toshihiko KuwabaraAbstract:A constitutive model capable of accurately reproducing the work-hardening behavior of sheet metals is fundamental to the creation and implementation of accurate numerical simulations of sheet metal forming. This chapter introduces the material testing methods that aid the quantification of the deformation behavior of sheet metals under biaxial compression, biaxial tension, combined tension–compression, and in-plane Stress Reversal. Examples of material testing and modeling results are also presented.
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Material Modeling of 980 MPa Dual Phase Steel Sheet Based on Biaxial Tensile Test and In-plane Stress Reversal Test
Journal of Solid Mechanics and Materials Engineering, 2011Co-Authors: Toshihiko Kuwabara, Tatsuya NakajimaAbstract:Uniaxial and biaxial tests were conducted to investigate the deformation behavior of dual phase steel sheet with a tensile strength of 980 MPa. Detailed measurements were made of the contours of plastic work and the directions of plastic strain rate at different levels of work-hardening for linear Stress paths in the first, second and fourth quadrants in the principal Stress space. Cruciform specimens were used in the first quadrant and the pure shear yield Stresses in the second and fourth quadrants were measured using combined tension-compression tests. The most appropriate anisotropic yield function for the material was determined by comparing the measured data with those calculated using selected yield functions. In-plane compression tests were also performed using the comb-shaped dies proposed by one of the authors. The measured work contours and directions of plastic strain rates were in good agreement with those calculated using the Yld2000-2d yield function with an exponent of 4. The Stress-strain curves measured for the in-plane Stress Reversal tests were in fair agreement with those calculated using the Chaboche-Rousselier model; however, this model is not capable of reproducing the nonlinear behavior of the material during unloading.
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Springback Analysis of Draw‐Bending of 980 MPa Cold Rolled Steel Sheet and Its Experimental Validation
2011Co-Authors: Nobuyasu Noma, Toshihiko KuwabaraAbstract:Draw‐bending experiment is carried out using a 1.2 mm‐thick high strength steel sheet with a tensile strength of 980 MPa and the residual curvature of the draw‐bent specimens are precisely measured. The die profile of the draw‐bending testing machine rotates, so that the effect of friction force on the curvature data after springback can be neglected. Moreover, in order to quantitatively evaluate the Bauschinger effect of the test material, Stress Reversal tests are performed using an in‐plane Stress Reversal testing machine. Furthermore, the finite element analyses (FEA) of the draw‐bending experiment are carried out. The effect of the work hardening models (isotropic or combined), element types (shell or solid), and the number of integration points in the through‐thickness direction on the amount of springback (residual curvature) are investigated in detail.
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Tension–compression asymmetry of phosphor bronze for electronic parts and its effect on bending behavior
International Journal of Plasticity, 2009Co-Authors: Toshihiko Kuwabara, Yutaka Kumano, Jindra Ziegelheim, Ikuya KurosakiAbstract:Abstract In-plane tension and compression experiments on copper alloy sheets (phosphor bronze) and 6000 series aluminum alloy sheets (AA6016-T4) were conducted using a specially designed testing apparatus. The apparatus is equipped with comb-type dies so that Stress–strain curves of a sheet specimen subjected to tension followed by compression, and vice versa, can be measured without buckling of the specimen, as well as those for monotonic tension and compression. A difference was observed in the flow Stresses between tension and compression for the as-received copper alloy, but not for the aluminum alloy. Moreover, Stress Reversal tests, such as tension followed by compression and compression followed by tension, were carried out in order to measure the Bauschinger effect. In the second part of the experiment, bending moment–curvature diagrams were measured for the as-received and pre-stretched specimens. The bending moment–curvature diagrams were compared with those calculated using the Stress–strain curves obtained from the tension–compression tests, and were in good agreement with those calculated with the tension–compression asymmetry and the Bauschinger effect correctly reproduced.
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tension compression asymmetry of phosphor bronze for electronic parts and its effect on bending behavior
International Journal of Plasticity, 2009Co-Authors: Toshihiko Kuwabara, Yutaka Kumano, Jindra Ziegelheim, Ikuya KurosakiAbstract:Abstract In-plane tension and compression experiments on copper alloy sheets (phosphor bronze) and 6000 series aluminum alloy sheets (AA6016-T4) were conducted using a specially designed testing apparatus. The apparatus is equipped with comb-type dies so that Stress–strain curves of a sheet specimen subjected to tension followed by compression, and vice versa, can be measured without buckling of the specimen, as well as those for monotonic tension and compression. A difference was observed in the flow Stresses between tension and compression for the as-received copper alloy, but not for the aluminum alloy. Moreover, Stress Reversal tests, such as tension followed by compression and compression followed by tension, were carried out in order to measure the Bauschinger effect. In the second part of the experiment, bending moment–curvature diagrams were measured for the as-received and pre-stretched specimens. The bending moment–curvature diagrams were compared with those calculated using the Stress–strain curves obtained from the tension–compression tests, and were in good agreement with those calculated with the tension–compression asymmetry and the Bauschinger effect correctly reproduced.
Ikuya Kurosaki - One of the best experts on this subject based on the ideXlab platform.
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Tension–compression asymmetry of phosphor bronze for electronic parts and its effect on bending behavior
International Journal of Plasticity, 2009Co-Authors: Toshihiko Kuwabara, Yutaka Kumano, Jindra Ziegelheim, Ikuya KurosakiAbstract:Abstract In-plane tension and compression experiments on copper alloy sheets (phosphor bronze) and 6000 series aluminum alloy sheets (AA6016-T4) were conducted using a specially designed testing apparatus. The apparatus is equipped with comb-type dies so that Stress–strain curves of a sheet specimen subjected to tension followed by compression, and vice versa, can be measured without buckling of the specimen, as well as those for monotonic tension and compression. A difference was observed in the flow Stresses between tension and compression for the as-received copper alloy, but not for the aluminum alloy. Moreover, Stress Reversal tests, such as tension followed by compression and compression followed by tension, were carried out in order to measure the Bauschinger effect. In the second part of the experiment, bending moment–curvature diagrams were measured for the as-received and pre-stretched specimens. The bending moment–curvature diagrams were compared with those calculated using the Stress–strain curves obtained from the tension–compression tests, and were in good agreement with those calculated with the tension–compression asymmetry and the Bauschinger effect correctly reproduced.
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tension compression asymmetry of phosphor bronze for electronic parts and its effect on bending behavior
International Journal of Plasticity, 2009Co-Authors: Toshihiko Kuwabara, Yutaka Kumano, Jindra Ziegelheim, Ikuya KurosakiAbstract:Abstract In-plane tension and compression experiments on copper alloy sheets (phosphor bronze) and 6000 series aluminum alloy sheets (AA6016-T4) were conducted using a specially designed testing apparatus. The apparatus is equipped with comb-type dies so that Stress–strain curves of a sheet specimen subjected to tension followed by compression, and vice versa, can be measured without buckling of the specimen, as well as those for monotonic tension and compression. A difference was observed in the flow Stresses between tension and compression for the as-received copper alloy, but not for the aluminum alloy. Moreover, Stress Reversal tests, such as tension followed by compression and compression followed by tension, were carried out in order to measure the Bauschinger effect. In the second part of the experiment, bending moment–curvature diagrams were measured for the as-received and pre-stretched specimens. The bending moment–curvature diagrams were compared with those calculated using the Stress–strain curves obtained from the tension–compression tests, and were in good agreement with those calculated with the tension–compression asymmetry and the Bauschinger effect correctly reproduced.
Jindra Ziegelheim - One of the best experts on this subject based on the ideXlab platform.
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Tension–compression asymmetry of phosphor bronze for electronic parts and its effect on bending behavior
International Journal of Plasticity, 2009Co-Authors: Toshihiko Kuwabara, Yutaka Kumano, Jindra Ziegelheim, Ikuya KurosakiAbstract:Abstract In-plane tension and compression experiments on copper alloy sheets (phosphor bronze) and 6000 series aluminum alloy sheets (AA6016-T4) were conducted using a specially designed testing apparatus. The apparatus is equipped with comb-type dies so that Stress–strain curves of a sheet specimen subjected to tension followed by compression, and vice versa, can be measured without buckling of the specimen, as well as those for monotonic tension and compression. A difference was observed in the flow Stresses between tension and compression for the as-received copper alloy, but not for the aluminum alloy. Moreover, Stress Reversal tests, such as tension followed by compression and compression followed by tension, were carried out in order to measure the Bauschinger effect. In the second part of the experiment, bending moment–curvature diagrams were measured for the as-received and pre-stretched specimens. The bending moment–curvature diagrams were compared with those calculated using the Stress–strain curves obtained from the tension–compression tests, and were in good agreement with those calculated with the tension–compression asymmetry and the Bauschinger effect correctly reproduced.
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tension compression asymmetry of phosphor bronze for electronic parts and its effect on bending behavior
International Journal of Plasticity, 2009Co-Authors: Toshihiko Kuwabara, Yutaka Kumano, Jindra Ziegelheim, Ikuya KurosakiAbstract:Abstract In-plane tension and compression experiments on copper alloy sheets (phosphor bronze) and 6000 series aluminum alloy sheets (AA6016-T4) were conducted using a specially designed testing apparatus. The apparatus is equipped with comb-type dies so that Stress–strain curves of a sheet specimen subjected to tension followed by compression, and vice versa, can be measured without buckling of the specimen, as well as those for monotonic tension and compression. A difference was observed in the flow Stresses between tension and compression for the as-received copper alloy, but not for the aluminum alloy. Moreover, Stress Reversal tests, such as tension followed by compression and compression followed by tension, were carried out in order to measure the Bauschinger effect. In the second part of the experiment, bending moment–curvature diagrams were measured for the as-received and pre-stretched specimens. The bending moment–curvature diagrams were compared with those calculated using the Stress–strain curves obtained from the tension–compression tests, and were in good agreement with those calculated with the tension–compression asymmetry and the Bauschinger effect correctly reproduced.
Yutaka Kumano - One of the best experts on this subject based on the ideXlab platform.
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Tension–compression asymmetry of phosphor bronze for electronic parts and its effect on bending behavior
International Journal of Plasticity, 2009Co-Authors: Toshihiko Kuwabara, Yutaka Kumano, Jindra Ziegelheim, Ikuya KurosakiAbstract:Abstract In-plane tension and compression experiments on copper alloy sheets (phosphor bronze) and 6000 series aluminum alloy sheets (AA6016-T4) were conducted using a specially designed testing apparatus. The apparatus is equipped with comb-type dies so that Stress–strain curves of a sheet specimen subjected to tension followed by compression, and vice versa, can be measured without buckling of the specimen, as well as those for monotonic tension and compression. A difference was observed in the flow Stresses between tension and compression for the as-received copper alloy, but not for the aluminum alloy. Moreover, Stress Reversal tests, such as tension followed by compression and compression followed by tension, were carried out in order to measure the Bauschinger effect. In the second part of the experiment, bending moment–curvature diagrams were measured for the as-received and pre-stretched specimens. The bending moment–curvature diagrams were compared with those calculated using the Stress–strain curves obtained from the tension–compression tests, and were in good agreement with those calculated with the tension–compression asymmetry and the Bauschinger effect correctly reproduced.
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tension compression asymmetry of phosphor bronze for electronic parts and its effect on bending behavior
International Journal of Plasticity, 2009Co-Authors: Toshihiko Kuwabara, Yutaka Kumano, Jindra Ziegelheim, Ikuya KurosakiAbstract:Abstract In-plane tension and compression experiments on copper alloy sheets (phosphor bronze) and 6000 series aluminum alloy sheets (AA6016-T4) were conducted using a specially designed testing apparatus. The apparatus is equipped with comb-type dies so that Stress–strain curves of a sheet specimen subjected to tension followed by compression, and vice versa, can be measured without buckling of the specimen, as well as those for monotonic tension and compression. A difference was observed in the flow Stresses between tension and compression for the as-received copper alloy, but not for the aluminum alloy. Moreover, Stress Reversal tests, such as tension followed by compression and compression followed by tension, were carried out in order to measure the Bauschinger effect. In the second part of the experiment, bending moment–curvature diagrams were measured for the as-received and pre-stretched specimens. The bending moment–curvature diagrams were compared with those calculated using the Stress–strain curves obtained from the tension–compression tests, and were in good agreement with those calculated with the tension–compression asymmetry and the Bauschinger effect correctly reproduced.
Vassilis Paschalis - One of the best experts on this subject based on the ideXlab platform.
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low vitamin c values are linked with decreased physical performance and increased oxidative Stress Reversal by vitamin c supplementation
European Journal of Nutrition, 2016Co-Authors: Vassilis Paschalis, Anastasios A Theodorou, Antonios Kyparos, Konstantina Dipla, Andreas Zafeiridis, George Panayiotou, Ioannis S Vrabas, Michalis G NikolaidisAbstract:It has been suggested that part of the failure of antioxidant supplementation to reduce oxidative Stress and promote health is that it has been administered in humans with normal levels of antioxidants. To test this hypothesis, we screened 100 males for vitamin C baseline values in blood. Subsequently, the 10 individuals with the lowest and the 10 with the highest vitamin C values were assigned in two groups. Using a placebo-controlled crossover design, the 20 selected subjects performed aerobic exercise to exhaustion (oxidant stimulus) before and after vitamin C supplementation for 30 days. The low vitamin C group had lower VO2max values than the high vitamin C group. Vitamin C supplementation in this group marginally increased VO2max. Baseline concentration of F2-isoprostanes and protein carbonyls was higher in the low vitamin C group compared to the high vitamin C group. Vitamin C supplementation decreased the baseline concentration of F2-isoprostanes and protein carbonyls in both groups, yet the decrease was greater in the low vitamin C group. Before vitamin C supplementation, F2-isoprostanes and protein carbonyls were increased to a greater extent after exercise in the high vitamin C group compared to the low vitamin C group. Interestingly, after vitamin C supplementation, this difference was narrowed. We show for the first time that low vitamin C concentration is linked with decreased physical performance and increased oxidative Stress and that vitamin C supplementation decreases oxidative Stress and might increase exercise performance only in those with low initial concentration of vitamin C.