セミナー発足に際してのごあいさつ(1997.4)

第 245 回 Q-NA セミナー
日     時2009 年 12月 1日 (火) 15:30 - 17:00
場     所九州大学伊都キャンパス 総合学習プラザ1階 工学部第10講義室
講 演 者Reza Miresmaeili (九州大学 大学院工学府)
題     目A Coupled Elastoplastic-Transient Hydrogen Diffusion Analysis to Simulate the Onset of Necking in Tension by Using the Finite Element Method
概     要Hydrogen-enhanced localized plasticity (HELP) is an acceptable mechanism for hydrogen embrittlement which is based on the experimental observations and the theoretical computations. The underlying principle in the HELP theory is that the presence of hydrogen causes the localization of the slip bands which results in the decrease of the fracture strength. In a sample under plane-strain tensile stress, plastic instability can lead to either the concentration of plastic flow in a narrow neck or bifurcation from homogeneous deformation into a mode of an exclusively localized narrow band of intense shear. Recently, it has been demonstrated that the presence of hydrogen can indeed induce shear banding bifurcation at macroscopic strains. By using a steady-state equilibrium equation for hydrogen diffusion analysis, the effect of hydrogen on the bifurcation of a homogeneous deformation in a plane-strain tension specimen into a necking or a shear localization mode of deformation has already been studied. In the present research, using a transient hydrogen diffusion analysis and introducing a new constitutive equation accompanied by considering the reduction in the local flow stress upon hydrogen dissolution into the lattice, the effect of hydrogen on shear localization is investigated. In addition, progress has been made in that, the changes in the distribution of the total and trapping hydrogen concentrations through the loading time and particularly during the development of the necking event have been determined.
備     考数理学研究院の伊都キャンパスへの移転に伴い,会場が変更となっています.ご注意ください.なお,お車でお越しの場合にはこの案内を印刷してご持参のうえ,入構の際に守衛所にてご掲示ください.

世話人
田上 大助 (九州大学 マス・フォア・インダストリ研究所)
渡部 善隆 (九州大学 情報基盤研究開発センター)

ご不明な点がございましたら、事務局: までお問い合わせ下さい。


トップ   編集 凍結 差分 バックアップ 添付 複製 名前変更 リロード   新規 一覧 単語検索 最終更新
Last-modified: 2009-12-04 (金) 09:59:00 (3663d)