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201 results on '"Kuroda, Koichi"'

10. New ductile fracture criterion for prediction of internal fracture in skew rolling

Author

Yamane, Koji, Shimoda, Kazuhiro, and Kuroda, Koichi

Subjects
Finite element method, health care facilities, manpower, and services, Plasticity -- Mathematical models, education, Plasticitat, Elements finits, Mètode dels, Skew Rolling, Internal fracture, Stress Triaxiality, Ductile Fracture Criterion, Plasticitat -- Models matemàtics, Matemàtiques i estadística::Anàlisi numèrica::Mètodes en elements finits [Àrees temàtiques de la UPC], health care economics and organizations
Abstract

Skew rolling is the process of reducing the diameter of a round billet. In this process, internal fracture may occur in the rolled material. This phenomenon is known as the Mannesmann effect. While there has been great discussion about the mechanism of internal fracture, it has yet to be fully clarified. To investigate the internal fracture initiation and propagation, we conducted hot rolling experiments and evaluated the stress and strain of the rolled material by elasto-plastic finite element analysis. The results show that the internal fracture arises on the internal surface in which shear stress acts owing to the combined effect of tensile and shear stress. In this paper, a new ductile fracture criterion is discussed to quantitatively predict the occurrence of internal fracture in skew rolling.

Published
2019

22. Toxicity of Agricultural Chemicals in Daphnia magna

Author

Matsumoto, Ken-ichi, Hosokawa, Mamoru, Kuroda, Koichi, and Endo, Ginji

Subjects
Immobilization, fungi, Daphnia magna, LC_50, Agricultural chemical, reproductive and urinary physiology, Brood
Abstract

Background : Daphnia magna is a useful aquatic organism for testing ecological toxicities of environmental pollutants. However, there were only a few studies on agricultural chemicals using these organisms. / Methods : We investigated acute and subchronic toxicities of 30 agricultural chemicals commonly used in Japan in D. magna. Acute toxicity of the agricultural chemicals was determined using the concentrations yielding 50% immobility of D. magna after 24 hr and 48 hr exposure as end points. D. magna was cultivated with the chemical and algae until the first brood production. Lethal toxicity and the number of survival broods were determined within 13 days....

Published
2009

31. Influential factor to dimensional precision of cold-drawn tubes.

Author

Kuroda, Koichi, Kawakami, Tadashi, Okui, Tatsuya, Akiyama, Masayoshi, and Kiuchi, Manabu

Abstract

Elastic–plastic finite element analyses were carried out to sort out the influential factors on the dimensional precision of cold-drawn stainless steel seamless tube for energy industry. Good agreement was obtained between the predicted dimensions and the measured dimensions of tube after drawing experiment for validity check. Geometrical parameters of tools and geometry of parent tube have little influence on the geometrical precision of finished tube. Most influential factor on the geometrical precision of drawn tube is the temperature of tools. Observation and measurement on a production line showed that the temperature of tools increases according to the increase in the number of drawn tubes. Increase in the temperature of tool leads to the change in the geometry of drawn tube. A methodology for evaluating the thermal expansion of tools is shown to take it into consideration the designing procedure of cold-drawing process by using finite element analysis. [ABSTRACT FROM PUBLISHER]

Published
2015
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36. Levels of annexin IV and V in the plasma of pregnant and postpartum women

Author

Masuda, Junko, primary, Takayama, Eiji, primary, Satoh, Ayano, primary, Ida, Michiru, primary, Shinohara, Tadashi, primary, Kojima-Aikawa, Kyoko, primary, Ohsuzu, Fumitaka, primary, Nakanishi, Kuniaki, primary, Kuroda, Koichi, primary, Murakami, Mitsutaka, primary, Matsumoto, Isamu, primary, and Suzuki, Kimihiro, additional

Published
2004
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