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15 results on '"Hara, Eiichi"'

3. Investigation of Strength Demonstration Test for Materials and Structures

Author

ITO, Seiichi, KATO, Hisaya, HARA, Eiichi, OKADA, Takao, and HOSHI, Hikaru

Subjects
MC法, 部材強度実証, 拡張ベイズ法, MIL値, 耐荷重実証, 打切り標本
Abstract

部材および構造物の強度実証に対する試験計画について、区間推定およびベイズ理論を応用した評価手法をまとめる。強度の不確定性評価において、部材試験では強度モデルの未知母数推定の精度を上げるために多数標本が用いられる。一方、構造部位や実機構造などの少量生産品では耐荷重性能が重要であり、多くの標本が得られる部材試験とは強度実証法が異なる。本報告では、多数標本による部材強度の実証試験(demonstration test)について区間推定理論を適用し、必要な標本数を設定する汎用の強度実証に向けた評価法を示す。また少量標本の構造物に対する強度実証では、既開発のベイズ法を応用した耐荷重試験(proof load test)計画について、取り扱う情報源の拡大に向けた手法を展開する。, In the evaluation of structural strength uncertainty, a large number of samples are used in the material strength test in order to improve the accuracy of model estimation of strength (estimation of unknown parameters). On the other hand, proof load performance is important for small amount products such as substructures and large-scale structures, and the strength demonstration method differs from the structural material strength test. For the demonstration test of material strength, the statistical intervals theory, which is studied in detail by Meeker et al., is applied, and the definition is unified and formulated for the material strength verification method. For strength verification of small sample structures, an extended Bayesian proof load test method that allows for the expansion of the information sources used is constructed., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA2130006000, レポート番号: JAXA-RM-21-002

Published
2021

5. Application of chronocoulometry method for measuring Fick's diffusion constant of thin coating layers.

Author

Morimoto, Tetsuya, Hara, Eiichi, and Katoh, Hisaya

Subjects
*THICK films, *PROTECTIVE coatings, *SURFACE coatings, *DIFFUSION, *AQUEOUS electrolytes, *SURFACE properties, *CHRONOAMPEROMETRY
Abstract

An applied electrochemical method in the form of a chronocoulometry technique is proposed for measuring Fick's diffusion constant of a thin protective coating layer over the conductive base materials. Using this method, the capacitance is monitored for a capacitor formed using the base material, an electrolyte such as aqueous NaCl, and an insulating coating layer in between. The capacitance increases when the distance between the base material and the electrolyte decreases in the diffusion of the electrolyte through the insulating coating layer. Therefore, the change in the capacitance provides a diffusion rate related to Fick's diffusion constant. Conventional gravimetric methods require a long measurement time to reach saturation, and thin coating layers of minimal weight increment through water diffusion were demonstrated to be inadequate for the methods. However, the new electrochemical method is appropriate for thin coating layers and requires a limited duration after the onset of diffusion. Experimental for 1-mm thick PA6 films provided Fick's diffusion constants of safer side with the new method of 15h by reflecting the heterogeneous properties of the surface, while the conventional gravimetric method in 360h provided smaller or danger-side values. [ABSTRACT FROM AUTHOR]

Published
2023
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7. Application of Bayesian expectation to reliability index on material strength

Author

Ito, Seiichi, Kato, Hisaya, Hara, Eiichi, and Okada, Takao

Subjects
ベイズ期待信頼度, AIC, 構造安全性・信頼性, MCMC法, MIL-A/B値
Abstract

信頼度と信頼水準を統合して、平明な一元評価を可能にする、ベイズ理論を応用した強度の信頼性評価モデルを構築する。ここでは標本や確率分布の未知母数の不確定性に対してベイズ理論を適用して、目的の強度レベル対する一元評価としてのベイズ期待信頼度を定義する。ベイズ法では工学的判断などの事前情報と標本結果を用いて、未知母数をベイズ理論によって推定する。推定された未知母数は事後確率分布として形成されるが、事後分布は未知母数に対する事前分布の設定に影響を受ける。本報告では事前分布の設定に依存しないマルコフチェーン・モンテカルロ(MCMC) 法を用い、得られた事後分布からMIL値に対する信頼度のベイズ期待値を求めて、これをMIL値に対応する一元評価指標とする。, The MIL-A/B (Military specification A and B-basis) values for the reliability assessment of material strength are evaluated by two factors of reliability (0.99 and 0.9 for the A and B values) and confidence level (0.95). Towards this evaluation method, the expected reliability index is modelled as a reliability grasping technique using Bayesian analysis that integrates reliability and confidence level. The Bayesian method is applied to the uncertainty evaluation of unknown parameters to define the Bayesian expected reliability as a unitary reliability index for the allowable material strength. The construction of the Bayesian reliability method and a concrete evaluation example for the MIL value of the material strength are shown in using MCMC (Markov chain Monte Carlo) which is a representative method of calculation statistics., 形態: 図版あり, Physical characteristics: Original contains illustrations, 資料番号: AA1830027000, レポート番号: JAXA-RM-18-011

Published
2019

8. JAXA Advanced Composites Database

Author

Morimoto, Tetsuya, Sugimoto, Sunao, Kato, Hisaya, Hara, Eiichi, Yasuoka, Tetsuo, Iwahori, Yutaka, Ogasawara, Toshio, and Ito, Seiichi

Subjects
力学特性データベース, CMH-17, JAXA-ACDB, BBA手法, CFRP
Abstract

本資料は、(独)宇宙航空研究開発機構(JAXA)および旧航空宇宙技術研究所(NAL)の複合材技術開発センター(ACETeC)を中心として取得された先進複合材料、特に炭素繊維強化樹脂系複合材料(CFRP)に関する各種力学特性の試験結果を整理したデータベースである。データベース形式としては、Composite Material Handbook(CMH-17)類似の構成となるような収集を進めており、この部分についてはJAXA:HDBKと称している。本データベースについては、現在JAXA-ACDBの呼称にてドメイン名を取得してインターネットを用いて登録ユーザへのデータ提供を行っている*が、活用の利便性をさらに向上させるため、技術研究資料として改めてここに出版する。*本技術資料の公開を踏まえ、インターネットによるデータ提供は2016年3月に終了した。, This database, which has been called 'JAXA: HDBK,' summarizes the mechanical performance for advanced composite materials, especially for carbon fiber reinforced composites (CFRPs). The data have been derived mainly by advanced composite evaluation technology center (ACETeC) at Japan Aerospace Exploration Agency (JAXA) and the predecessor national aerospace lab. (NAL) in the form of Composite Material Handbook(CMH-17). JAXA: HDBK website www.jaxa-acdb.com *has been provided the on-line access database, and this JAXA Research and Development Memorandum(JAXA-RM) has been published in booklet form for the user convenience. *The website has been closed since March 2016, after the publication of this JAXA-RM., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1730022000, レポート番号: JAXA-RM-17-004

Published
2018

10. JAXA Advanced Composites Database

Author

Morimoto, Tetsuya, Sugimoto, Sunao, Katoh, Hisaya, Hara, Eiichi, Yasuoka, Tetsuo, Iwahori, Yutaka, Ogasawara, Toshio, and Ito, Seiichi

Subjects
力学特性データベース, CMH-17, JAXA-ACDB, BBA手法, CFRP
Abstract

本資料は、(独）宇宙航空研究開発機構(JAXA)および旧航空宇宙技術研究所(NAL)の複合材技術開発センター(ACETeC)を中心として取得された先進複合材料、特に炭素繊維強化樹脂系複合材料(CFRP)に関する各種力学特性の試験結果を整理したデータベースである。データベース形式としては、Composite Material Handbook(CMH-17)類似の構成となるような取集を進めており、この部分についてはJAXA:HDBKと称している。本データベースについては、現在JAXA-ACDBの呼称にてドメイン名を取得してインターネットを用いて登録ユーザへのデータ提供を行っているが、活用の利便性をさらに向上させるため、技術研究資料として改めてここに出版する。, This database, which has been called “JAXA: HDBK,” summarizes the mechanical performance for advanced composite materials, especially for carbon fiber reinforced composites (CFRPs). The data have been derived mainly by advanced composite evaluation technology center (ACETeC) at Japan Aerospace Exploration Agency (JAXA) and the predecessor national aerospace lab. (NAL) in the form of Composite Material Handbook (CMH-17). JAXA: HDBK website www.jaxa-acdb.com has been provided the on-line access database, and this JAXA Research and Development Memorandum (JAXA-RM) has been published in booklet form for the user convenience., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1530007000, レポート番号: JAXA-RM-14-004

Published
2015

11. Influence of specimen geometry on apparent Poisson's ratio evaluated under the compressive loading of quasi-isotropic CFRP laminate.

Author

Hara, Eiichi, Katoh, Hisaya, Iwahori, Yutaka, and Yokozeki, Tomohiro

Subjects
*COMPRESSION loads, *STRAINS & stresses (Mechanics), *STRESS concentration, *LAMINATED materials, *POISSON'S ratio, *FINITE element method
Abstract

The effects of specimen geometry on the Poisson's ratio of a quasi-isotropic carbon-fiber-reinforced polymer laminate were examined using compression tests. In particular, the divergence of the apparent Poisson's ratio from the theoretical value was experimentally determined for a decreasing specimen width/thickness ratio (b/t). The observed tendency was then confirmed by simulations using a finite element analysis (FEA). The FEA was performed using a 3D model of the specimens to investigate the strain and stress distribution. In the evaluation of the apparent Poisson's ratio, the strain in the width direction was shown to vary under the condition of low b/t. The FEA results revealed that changes to the width strain were caused by cross-sectional deformation under compressive loading, resulting from differences in layer angles and stiffness between the outermost and inner layers. [ABSTRACT FROM AUTHOR]

Published
2021
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15. Out-of-plane tensile modulus of CFRP laminates by 3-point bending test.

Author

Hara, Eiichi, Yokozeki, Tomohiro, Hatta, Hiroshi, Iwahori, Yutaka, and Ishikawa, Takashi

Subjects
*TENSILE strength, *MODULUS of elasticity, *CARBON fiber-reinforced plastics, *LAMINATED materials, *BENDING (Metalwork)
Abstract

To propose a test method for the out-of-plane tensile modulus of laminated carbon fiber-reinforced plastics, 3-point bending tests using a laminated CFRP with the span direction coinciding with out-of-plane (through-the-thickness) direction were performed. It was demonstrated that the apparent bending modulus depends on the length of span to thickness ratio (L/t) and the tensile modulusEto shear modulusGratio (E/G). Sensitivity analyses were performed to select the length of span to thickness ratio in order to evaluate the bending modulus near material modulus. Consequently, it is predicted that the bending modulus performed with theL/t > 25 bending specimen is equivalent to tensile modulus, if the apparent bending modulus were evaluated from 1 to 15 GPa, while modified equations for the out-of-plane modulus of QI-CFRP laminates obtained by three-dimensional laminate theory were also derived. This modification took stress condition in consideration of the small in-plane size like bending specimens into account. Moreover, it is demonstrated that apparent bending moduli were evaluated between upper and lower bound solutions. The upper bound solution is an out-of-plane modulus based on existing three-dimensional laminate theory, and the other is modified out-of-plane modulus. [ABSTRACT FROM PUBLISHER]

Published
2015
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