著者

小笠原 永久 千葉 矩正 山田 浩之 Xi CHEN

出版者

The Japanese Society for Experimental Mechanics

雑誌

実験力学 (ISSN:13464930)

巻号頁・発行日

vol.12, no.1, pp.26-32, 2012-03-28 (Released:2012-09-28)

参考文献数

13

被引用文献数

1

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An identification method with a sharp indentation for elastoplastic properties of film/substrate system is proposed. The method is based on extensive finite element computation on "soft film on hard substrate" cases indented with a sharp indenter. The method utilizes the substrate effect on load versus displacement relation in the indentation; this effect has often been regarded as undesirable. The computational results are expressed as response surfaces in a material parameter space. Based on the surfaces, and employing experimentally obtained load versus displacement relation, the elastoplastic properties of the film are identified. To determine the elastoplastic properties more accurately, it is important to use not only the loading curve but also the unloading curve. Numerical examples determined by this method for film/substrate system are given.

著者

石川 真志 八田 博志 笠野 英行 小笠原 永久 山田 浩之 宇都宮 真

出版者

徳島大学

雑誌

基盤研究(B)

巻号頁・発行日

2014-04-01

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本研究は赤外線サーモグラフィを用いた大型の構造物の効率的な非破壊検査手法の開発を目標として検討を行った。実験の結果、アクティブサーモグラフィ検査時の加熱方法としてレーザー走査加熱を利用することで、10 m遠方に位置する対象物であっても内部の欠陥検出が可能であることが確認された。また、温度データへのフーリエ変換により得られる位相画像を利用することで、欠陥検出が容易となること、および高周波数の位相画像に注目して検査を行うことで検査時間の短縮が可能であることも確認された。これらの技術を組み合わせることで、高効率かつ高精度な検査の実現が期待される。

著者

上 剛司 山田 浩之 小笠原 永久

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.856, pp.17-00261-17-00261, 2017 (Released:2017-12-25)

参考文献数

37

被引用文献数

1

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Indentation tests are used to determine the local mechanical properties of materials. Previously, the indentation strain rate was correlated with the strain rate in uniaxial tests based on the hardness, which was the obtained load divided by the cross-sectional area. However, the hardness can be influenced by pile-up of material after indentation. The purpose of this study was to relate the indentation strain rate with the uniaxial strain rate through serration behavior. The material used in this study was 5082 aluminum alloy, whose main alloying elements are aluminum and magnesium, and which is known to exhibit serration at certain temperatures and strain rates. Quasi-static uniaxial tensile tests were performed at strain rates from 10-4 to 10-1 s-1 at room temperature. Micro-indentation using a Berkovich indenter was performed at constant loading rates from 0.7 to 350 mN/s. The loading curvature, which was defined as the load divided by the square of the displacement, was used instead of the hardness to avoid the pile-up effect. As a result, the serrated loading curvature in the indentation tests was obtained as the decreasing loading rate. The effective strain rate, which was defined as the derivative of the load with respect to time divided by two times the applied load, decreased with increasing displacement. The serrated loading curvature changed its behavior as the effective strain rate decreased. It behaved similarly to the serration observed in uniaxial tensile tests. It was found that the indentation strain rate is correlated with the strain rate in uniaxial tensile tests through the serration behavior.

著者

山田 浩之 佐藤 元宣 小笠原 永久 吉本 充宏

出版者

特定非営利活動法人日本火山学会

雑誌

日本火山学会講演予稿集

巻号頁・発行日

vol.2015, 2015-09-28