著者

藤川 正毅 石川 清貴 真壁 朝敏 田中 真人 笹川 崇 表 竜二

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

pp.15-00454, (Released:2016-01-15)

参考文献数

13

被引用文献数

6 5

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This paper proposes a novel implementation scheme of geometrically nonlinear finite element programs, which automatically compute exact internal force vectors and element stiffness matrices by numerically differentiating a strain energy function at each element. This method can significantly simplify the complex implementation procedure which is often observed in conventional finite element implementations, since it never requires B matrices, stress tensors, and elastic tensors by hand. The proposed method is based on a highly accurate numerical derivatives which use hyper-dual numbers and never suffer from any round-off and truncation errors. Several numerical examples are performed to demonstrate the effectiveness and robustness of the proposed method.

著者

張 学超 森 敬祐 真壁 朝敏 安藤 新二 井上 晋一

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会九州支部講演論文集

巻号頁・発行日

vol.2021, 2021

著者

真壁 朝敏 S. M. Moshiar RAHAMAN 名嘉 海人 真鍋 光輝

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会九州支部講演論文集

巻号頁・発行日

vol.2021, 2021

著者

張 学超 森 敬祐 真壁 朝敏 井上 晋一 安藤 新二

出版者

公益社団法人 日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.70, no.6, pp.473-478, 2021

被引用文献数

1

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<p>Push-pull fatigue tests of rolled magnesium alloys AZ31 and AZX912 were performed with a side-notch plate specimen to examine the effect of a single overload on the crack growth behavior under a stress ratio of -1. The behavior in retardation of crack growth was unclear in the case of AZ31 because the crack growth rate was relatively higher at the overload point. However, this was observed clearly, when the branching of the crack tip happened in the case of AZX912. The geometry of the fracture surface and the changes in crack growth path were related to the crack growth behavior. The crack opening level became higher when the crack growth rate was lower. Therefore, the crack closure is related to the retardation of the crack growth rate. When the branching of a crack tip occurred, not only the residual compression stress at crack front but also the variation of local crack growth direction after overload affected the fatigue crack growth behavior. </p>

著者

RAHMAN S. M. MOSHIAR 名嘉 海人 真壁 朝敏

出版者

一般社団法人 日本高圧力技術協会

雑誌

圧力技術 (ISSN:03870154)

巻号頁・発行日

vol.59, no.2, pp.52-60, 2021

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There is a good correlation between the <I>S</I>-<I>N</I> curve and crack growth law in carbon steel. Also, the fatigue limit of that can be evaluated from the param-eters of hardness and crack initiation conditions. The crack initiation behavior is related to the distribution of microstructures and the sizes of inclu-sions. Therefore, when the fatigue limit and life of carbon steel are predicted, it is better to consider the initial crack length and crack growth behavior. In this study, one such case was investigated by push-pull with constant stress amplitude by using 0.45% carbon steel. The initial crack lengths were varied with the specimen used and testing conditions. The prediction method of the <I>S</I>-<I>N</I> curve from a corrected crack growth law in such case was pro-posed. Also, a method of prediction of fatigue limit and life from the point of safety was discussed in this study.

著者

ラーマン エス エム モシアール 真壁 朝敏 名嘉 海人 山内 章広

出版者

一般社団法人 日本高圧力技術協会

雑誌

圧力技術 (ISSN:03870154)

巻号頁・発行日

vol.58, no.4, pp.209-215, 2020

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There is a good correlation between the static strength and fatigue limit in many carbon steels. However, in the case of some commercially sold carbon steel, the fatigue limit cannot be evaluated from the static strength. Care should be taken when those materials are used for ma-chine equipment. In the case of some materials, there is decrease in fa-tigue limit from the expected values of Vickers hardness. In this study, one such case was investigated by push-pull. The examinations of the <I>S</I>-<I>N</I> curves and crack growth behavior were performed. Then, it was discussed that decrease in fatigue limit was related to the existence of inclusions or defects of unexpectedly large size. When such material as used in the present study is used for a machine equipment, the decrease of fatigue limit should be taken into account to determine an applied load.

著者

森 敬祐 真壁 朝敏 安藤 新二 井上 晋一

出版者

一般社団法人 日本高圧力技術協会

雑誌

圧力技術 (ISSN:03870154)

巻号頁・発行日

vol.58, no.1, pp.14-21, 2020

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Fatigue crack growth tests of rolled magnesium alloy AZ31 were performed with a side-notch plate specimen under negative mean stress conditions. In the results of the present study, even if the experimental conditions were the same, the crack growth behavior varied depending on the condition of the specimen and depending on the microstructure. The local friction between large size and small size crystals and the shear deformation are expected to be related to the crack closure. The crack growth rate was affected by the crack opening stress. When the crack growth rate was lower level, the crack closure behavior worked due to the plastic deformation and the roughness of the fracture surface. There was local rough pattern which work as the shear lip at sides of the crack surface.

著者

田中 興 藤川 正毅 真壁 朝敏 石川 清貴

出版者

一般社団法人 日本機械学会

雑誌

計算力学講演会講演論文集 2015.28 (ISSN:24242799)

巻号頁・発行日

pp._223-1_-_223-2_, 2015-10-10 (Released:2017-06-19)

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ゲル材料は高い衝撃吸収性能などの特異な性質をもつものが多く開発されている.そしてゲル材料の性能を評価するためのシミュレーション法の確立が望まれている.その中でも特に長期使用環境下におけるゲル材料の力学特性の研究は,重要性があるにも関わらず研究が進んでいないのが現状である.そこで本研究では商用ゲル材料を対象とし,大変形下におけるクリープ挙動を実験により明らかにする.そして,シミュレーションのための材料モデルとその材料定数値について検討し,その有効性を確認する.

著者

藤川 正毅 石川 清貴 真壁 朝敏 田中 真人 笹川 崇 表 竜二

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

2016

被引用文献数

2

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This paper presents a novel Formulated Alpha FEM with deviatoric / volumetric split, which is combination of standard FEM and Node-based Smoothed FEM (NS-FEM), to compute highly accurate deformation in mechanical problems using tetrahedral elements. The essential idea of the method is the use of a deviatoric alpha formulated on basis of the results of cantilever problem, and the volumetric alpha introduced NS-FEM. The features of this proposed method are: 1) immune from volumetric locking, 2) less sensitive to element distortion, and 3) to be carried out with the same preprocessing as standard FEM from user's viewpoint. Several numerical examples show that the present method achieves higher accuracy compared to the standard FEM and Edge-based/NS-FEM which is known to be one of the best S-FEM formulations.

著者

中山 卓弥 真壁 朝敏 藤川 正毅 新川 和夫

出版者

一般社団法人 日本高圧力技術協会

雑誌

圧力技術 (ISSN:03870154)

巻号頁・発行日

vol.54, no.2, pp.50-59, 2016

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The fatigue limit and crack growth behavior of slit specimens of epoxy base carbon composites were investigated. The fatigue limit was defined by maximum stress amplitude that the specimen endured 106 times stress repeating. Also, that was calculated by net stress at ligament. Carbon fiber directions were parallel and perpendicular to the load axis. The highest value of fatigue limit was obtained when all fiber directions were parallel to the load axis. However, crack grew along the fiber direction or load axis in the case of long slit. In the cases of two carbon directions that is, parallel and perpendicular to the load axis, the fatigue limits were evaluated from the result of the specimen that all carbon directions were parallel to the load axis. When measured value of fatigue limit was higher than the evaluated value, it was expected that the strain constraint occurred due to resistance of fiber in perpendicular to the load axis. When the measured value was lower, the peeling of fiber from epoxy was expected to be occurred. According to those results, it was expected that fatigue limit of smooth specimen of carbon composites with long fiber can be evaluated from the results of slit specimens

著者

中山 卓弥 真壁 朝敏 藤川 正毅 新川 和夫

出版者

一般社団法人 日本高圧力技術協会

雑誌

圧力技術 (ISSN:03870154)

巻号頁・発行日

vol.54, no.2, pp.50-59, 2016-03-25 (Released:2016-04-29)

参考文献数

7

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The fatigue limit and crack growth behavior of slit specimens of epoxy base carbon composites were investigated. The fatigue limit was defined by maximum stress amplitude that the specimen endured 106 times stress repeating. Also, that was calculated by net stress at ligament. Carbon fiber directions were parallel and perpendicular to the load axis. The highest value of fatigue limit was obtained when all fiber directions were parallel to the load axis. However, crack grew along the fiber direction or load axis in the case of long slit. In the cases of two carbon directions that is, parallel and perpendicular to the load axis, the fatigue limits were evaluated from the result of the specimen that all carbon directions were parallel to the load axis. When measured value of fatigue limit was higher than the evaluated value, it was expected that the strain constraint occurred due to resistance of fiber in perpendicular to the load axis. When the measured value was lower, the peeling of fiber from epoxy was expected to be occurred. According to those results, it was expected that fatigue limit of smooth specimen of carbon composites with long fiber can be evaluated from the results of slit specimens

著者

藤川 正毅 石川 清貴 真壁 朝敏 田中 真人 笹川 崇 表 竜二

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.82, no.834, pp.15-00454-15-00454, 2016

被引用文献数

5

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This paper proposes a novel implementation scheme of geometrically nonlinear finite element programs, which automatically compute exact internal force vectors and element stiffness matrices by numerically differentiating a strain energy function at each element. This method can significantly simplify the complex implementation procedure which is often observed in conventional finite element implementations, since it never requires B matrices, stress tensors, and elastic tensors by hand. The proposed method is based on a highly accurate numerical derivatives which use hyper-dual numbers and never suffer from any round-off and truncation errors. Several numerical examples are performed to demonstrate the effectiveness and robustness of the proposed method.

著者

藤川 正毅 石川 清貴 真壁 朝敏 田中 真人 笹川 崇 表 竜二

出版者

The Japan Society of Mechanical Engineers

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

2016

被引用文献数

5

---

This paper proposes a novel implementation scheme of geometrically nonlinear finite element programs, which automatically compute exact internal force vectors and element stiffness matrices by numerically differentiating a strain energy function at each element. This method can significantly simplify the complex implementation procedure which is often observed in conventional finite element implementations, since it never requires B matrices, stress tensors, and elastic tensors by hand. The proposed method is based on a highly accurate numerical derivatives which use hyper-dual numbers and never suffer from any round-off and truncation errors. Several numerical examples are performed to demonstrate the effectiveness and robustness of the proposed method.