The Experts below are selected from a list of 180252 Experts worldwide ranked by ideXlab platform
Kenichiro Mori - One of the best experts on this subject based on the ideXlab platform.
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tailored die quenching of steel parts having Strength Distribution using bypass resistance heating in hot stamping
Journal of Materials Processing Technology, 2013Co-Authors: Kenichiro Mori, Tomoyoshi Maeno, K MongkolkajiAbstract:Abstract A tailored die quenching process of steel parts having a Strength Distribution using bypass resistance heating in hot stamping was developed. In the tailored die quenching process, zones requiring high Strength in a quenchable steel sheet were heated, and then were quenched. In the bypass resistance heating, zones in contact with copper bypasses having a low resistance and large cross-sectional area were not heated due to the passage of the current though the copper bypasses. The bypass resistance heating was stable even for the heavy current in rapid heating of the steel sheets because of passage of current in one direction, and the electrical power loss was small. The hardenability for the bypass resistance heating was first examined by sandwiching a partially heated sheet between large steel blocks without deformation. Next, the tailored die quenching process using bypass resistance heating in the hat-shaped bending of the steel sheet was performed to form a part having high Strength around the corners. A hat-shaped part having a tensile Strength of approximately 1.5 GPa around the corners was formed, and the input energy and punching load in the bottom of the bent sheet were considerably smaller than those for whole heating.
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tailor die quenching in hot stamping for producing ultra high Strength steel formed parts having Strength Distribution
Cirp Annals-manufacturing Technology, 2010Co-Authors: Kenichiro Mori, Y OkudaAbstract:Abstract Tailor die quenching in the hot stamping of quenchable steel sheets was developed to produce ultra-high Strength steel formed parts having Strength Distribution. Local portions of the heated sheet were quenched by holding grooved tools at the bottom dead centre during the stamping. Non-contact portions were generated in the sheet by grooving the tools, and thus the Strength in the contact portions is high owing to the quenching and that in the non-contact portions is low owing to the lack of the quenching. Hat-shaped products having a tensile Strength of approximately 1.5 GPa only at four corners were formed.
Lianxi Zheng - One of the best experts on this subject based on the ideXlab platform.
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a modified weibull model for tensile Strength Distribution of carbon nanotube fibers with strain rate and size effects
Applied Physics Letters, 2012Co-Authors: J H L Pang, Jinyuan Zhou, Yani Zhang, Zhaoyao Zhan, Lianxi ZhengAbstract:Fundamental studies on the effects of strain rate and size on the Distribution of tensile Strength of carbon nanotube (CNT) fibers are reported in this paper. Experimental data show that the mechanical Strength of CNT fibers increases from 0.2 to 0.8 GPa as the strain rate increases from 0.00001 to 0.1 (1/s). In addition, the influence of fiber diameter at low and high strain rate conditions was investigated further with statistical analysis. A modified Weibull Distribution model for characterizing the tensile Strength Distribution of CNT fibers taking into account the effect of strain rate and fiber diameter is proposed.
K Mongkolkaji - One of the best experts on this subject based on the ideXlab platform.
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tailored die quenching of steel parts having Strength Distribution using bypass resistance heating in hot stamping
Journal of Materials Processing Technology, 2013Co-Authors: Kenichiro Mori, Tomoyoshi Maeno, K MongkolkajiAbstract:Abstract A tailored die quenching process of steel parts having a Strength Distribution using bypass resistance heating in hot stamping was developed. In the tailored die quenching process, zones requiring high Strength in a quenchable steel sheet were heated, and then were quenched. In the bypass resistance heating, zones in contact with copper bypasses having a low resistance and large cross-sectional area were not heated due to the passage of the current though the copper bypasses. The bypass resistance heating was stable even for the heavy current in rapid heating of the steel sheets because of passage of current in one direction, and the electrical power loss was small. The hardenability for the bypass resistance heating was first examined by sandwiching a partially heated sheet between large steel blocks without deformation. Next, the tailored die quenching process using bypass resistance heating in the hat-shaped bending of the steel sheet was performed to form a part having high Strength around the corners. A hat-shaped part having a tensile Strength of approximately 1.5 GPa around the corners was formed, and the input energy and punching load in the bottom of the bent sheet were considerably smaller than those for whole heating.
D A Koss - One of the best experts on this subject based on the ideXlab platform.
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effect of cleaning and abrasion induced damage on the weibull Strength Distribution of sapphire fiber
Journal of the American Ceramic Society, 1994Co-Authors: Eric R Trumbauer, John R Hellmann, David L Shelleman, D A KossAbstract:Fractographic analysis revealed the presence of concurrent flaw populations in sapphire fibers which were tensile tested in the as-received condition (sized and unsized) and after various cleaning procedures. The following flaw populations were identified: surface flaws attributed to handling and abrasion damage (type A), volume or internal flaws attributed to shrinkage voids which form during the manufacturing process (type B), localized fiber surface reaction flaws introduced during the flame-cleaning procedure (type C), and self-abrasion surface flaws intentionally introduced on unsized fibers (type D). The Strength Distribution associated with each flaw type was characterized using a censored data Weibull analysis for both the least-squares and maximum-likelihood estimation methods. The Strength Distribution for type C (flame-cleaning) flaws exhibited an approximately 20% degradation in Strength compared to the Distribution for type A flaws. The Strength Distribution for type D (self-abrasion) flaws exhibited an approximately 35% degradation in Strength compared to the Strength Distribution for type A flaws. This result underscores the need for fiber sizings to prevent damage during shipping and handling. However, higher purity sizings and/or improved procedures for sizing removal are required to mitigate cleaning-induced fiber Strength degradation during composite fabrication.
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Effect of Cleaning and Abrasion‐Induced Damage on the Weibull Strength Distribution of Sapphire Fiber
Journal of the American Ceramic Society, 1994Co-Authors: Eric R Trumbauer, John R Hellmann, David L Shelleman, D A KossAbstract:Fractographic analysis revealed the presence of concurrent flaw populations in sapphire fibers which were tensile tested in the as-received condition (sized and unsized) and after various cleaning procedures. The following flaw populations were identified: surface flaws attributed to handling and abrasion damage (type A), volume or internal flaws attributed to shrinkage voids which form during the manufacturing process (type B), localized fiber surface reaction flaws introduced during the flame-cleaning procedure (type C), and self-abrasion surface flaws intentionally introduced on unsized fibers (type D). The Strength Distribution associated with each flaw type was characterized using a censored data Weibull analysis for both the least-squares and maximum-likelihood estimation methods. The Strength Distribution for type C (flame-cleaning) flaws exhibited an approximately 20% degradation in Strength compared to the Distribution for type A flaws. The Strength Distribution for type D (self-abrasion) flaws exhibited an approximately 35% degradation in Strength compared to the Strength Distribution for type A flaws. This result underscores the need for fiber sizings to prevent damage during shipping and handling. However, higher purity sizings and/or improved procedures for sizing removal are required to mitigate cleaning-induced fiber Strength degradation during composite fabrication.
W. K. Tso - One of the best experts on this subject based on the ideXlab platform.
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DESIRABLE Strength Distribution FOR ASYMMETRIC STRUCTURES WITH Strength-STIFFNESS DEPENDENT ELEMENTS
Journal of Earthquake Engineering, 2004Co-Authors: B. Myslimaj, W. K. TsoAbstract:Recent studies have shown that for many reinforced concrete lateral force-resisting elements (LFRE) stiffness is dependent on Strength, and as a result Strength assign-ment to these elements would affect both the Strength and stiffness Distributions in a structure. As a consequence, stiffness Distribution cannot be considered known prior to Strength assignment. This implies that in assigning Strength to LFRE, the designer has the ability not only to prescribe the Strength Distribution, but also indirectly control the stiffness Distribution in the structure. In this paper, a study is made on the seis-mic performance of a number of single-story structures to reconfirm that the “balanced CV-CR location” criterion, previously suggested by the writers, constitutes a desirable Strength/stiffness Distribution for minimising torsional response of asymmetric reinforced concrete structures.
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a Strength Distribution criterion for minimizing torsional response of asymmetric wall type systems
Earthquake Engineering & Structural Dynamics, 2002Co-Authors: B. Myslimaj, W. K. TsoAbstract:In order to mitigate the effect of torsion during earthquakes, most seismic codes of the world provide design guidelines for Strength Distribution based on the traditional perception that element stiffness and Strength are independent parameters. Recent studies have pointed out that for an important class of widely used structural elements such as reinforced concrete flexural walls, stiffness is a Strength-dependent parameter. This implies that the lateral stiffness Distribution in a wall-type system cannot be defined prior to the assignment of elements' Strength. Consequently, stiffness eccentricity cannot be computed readily and the current codified torsional provisions cannot be implemented in a straightforward manner. In this study, an alternate guideline for Strength Distribution among lateral force resisting elements is presented. To develop such a guideline, certain issues related to the dynamic behaviour of asymmetric wall-type systems during a damaging earthquake were examined. It is shown that both stiffness and Strength eccentricity are important parameters affecting the seismic response of asymmetric wall-type systems. In particular, results indicate that torsional effects can be minimized by using a Strength Distribution that results in the location of the centre of Strength CV and the centre of rigidity CR on the opposite sides of the centre of mass CM. Copyright © 2001 John Wiley & Sons, Ltd.
