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21 results on '"Tomoda, Yuichi"'

5. AE Monitoring of Corrosion Process in Reinfoced Concrete under Cyclic Wet and Dry Condition

Author

Kawasaki, Yuma, Kitaura, Misuzu, Tomoda, Yuichi, and Ohtsu, Masayasu

Subjects
Corrosion, 501.55, SiGMA Analysis, Salt Attack, Acoustic Emission
Abstract

Various deterioration and damage in reinforced concrete (RC) have been reported. Since salt is one of deterioration causes of RC, monitoring and diagnosis against deterioration are key issues. Thus, development of non-destructive evaluation (NDE) technique is important to assess corrosion process. To identify the onset of corrosion and the nucleation of corrosion-induced cracking in concrete due to expansion of corrosion products, continuous acoustic emission (AE) monitoring is available. In order to clarify these phenomena, cyclic wet and dry tests are performed in a laboratory. The SiGMA (Simplified Green's functions for Moment tensor Analysis) procedure is applied to AE waveforms to identify source kinematics of micro-crack locations, types and orientations. This study shows that the onset of corrosion and the nucleation of corrosion-induced cracking in concrete are visually identified. Then, cracking mechanisms due to the expansion of corrosion products are quantitatively clarified.

Published
2010

6. Monitoring Corrosion-Induced Cracks in Concrete by Acoustic Emission

Author

Tomoda, Yuichi, Mori, Kanako, Kawasaki, Yuma, and Ohtsu, Masayasu

Subjects
511.7
Abstract

Concrete structures suffer from the corrosion of reinforcing steel-bars due to severe environments, in particular, chloride attack. Acoustic Emission (AE) techniques have been extensively applied to concrete and concrete structures. In order to identify the onset of corrosion and the nucleation of concrete cracking due to expansion of corrosion products, continuous AE monitoring is available. These corrosion-induced cracks in concrete are studies in an accelerated corrosion test, where kinematics of micro-cracks is identified by SiGMA (Simplified Green's functions for Moment tensor Analysis). Monitoring the corrosion process of rebar by AE, it is confirmed that the onset of corrosion and the nucleation of corrosion-induced cracks in concrete are successfully identified. Then, generating mechanisms of corrosion-induced cracks are clarified by the SiGMA analysis.

Published
2010

7. ジッケンシツ ノ リヨウ ジョウキョウ

Author

Tomoda, Yuichi

Abstract

九州地区総合技術研究会in熊本大学, 第21回情報処理センター等担当者技術研究会(2009年9月3.4日開催) ポスター発表Ⅱ

Published
2009

8. Mechanism and monitoring technique of corrosion in reinforced concrete

Author

Tomoda, Yuichi

Subjects
自然電位法, 非破壊検査法, 電食・脱塩実験, 塩害, 377.5, アコースティック・エミッション法, AE法, 塩化物イオン浸透, 暴露実験
Abstract

本論文は、鉄筋コンクリートの腐食機構の解明とアコースティック・エミッション（AE）法を用いた非破壊検査法により塩害による劣化進行過程の定量的腐食モニタリングすることを目的としたものである。

Published
2006

15. Recycled Coarse Aggregate Produced by Pulsed Discharge in Water

Author

Namihira, Takao, primary, Shigeishi, Mitsuhiro, additional, Nakashima, Kazuyuki, additional, Murakami, Akira, additional, Kuroki, Kaori, additional, Kiyan, Tsuyoshi, additional, Tomoda, Yuichi, additional, Sakugawa, Takashi, additional, Katsuki, Sunao, additional, Akiyama, Hidenori, additional, and Ohtsu, Masayasu, additional

Published
2006
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18. Acoustic Emission Techniques for Rebar Corrosion in Reinforced Concrete.

Author

Grosse, Christian U., Ohtsu, Masayasu, and Tomoda, Yuichi

Abstract

Corrosion of reinforcing steel is modeled phenomenologically as corrosion losses of three phases. At the 1st phase, corrosion is initiated in reinforcement. The rate of the corrosion loss decreases at the 2nd phase under aerobic conditions. At the 3rd phase of anaerobic corrosion, the expansion of reinforcing steel due to corrosion product nucleates concrete cracking. In order to identify the onset of corrosion and the nucleation of concrete cracking based on this model, continuous AE monitoring in reinforced concrete specimens was conducted in a cyclic wet and dry test. High AE activities were characteristically observed twice during the corrosion process. AE parameter analysis of hits, events and locations demonstrates that AE monitoring is readily applicable to detect the corrosion in rebar and to identify the corrosion process. [ABSTRACT FROM AUTHOR]

Published
2007
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21. Phenomenological Model of Corrosion Process in Reinforced Concrete Identified by Acoustic Emission.

Author

Ohtsu, Masayasu and Tomoda, Yuichi

Subjects
CONCRETE corrosion, CONCRETE, CONSTRUCTION materials, MATERIALS testing, CRACKING of concrete, CONCRETE defects, ACOUSTIC emission, STRESS waves, ACOUSTICAL engineering
Abstract

This article presents a study regarding the phenomenological model of corrosion process in reinforced concrete identified by acoustic emission. At the first phase of the corrosion process, corrosion initiates in reinforcing bar. At the second phase, the rate of the corrosion loss decreases under aerobic conditions. Then the expansion of the reinforcing bar due to corrosion products nucleates concrete cracking at the third phase of anaerobic corrosion. Continuous acoustic emission monitoring was conducted to identify such a corrosion process.

Published
2008
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