Construction of nano/micro fracture mechanics

纳米/微米断裂力学的构建

• 批准号: 13650092
• 负责人: NOGUCHI Hiroshi
• 金额: $ 2.24万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650092/
• 关键词: Molecular Dynamics; Distribution Method; Fracture Toughness; Single Crystal; Ductile-brittle Transition; Meso-characteristics; Inclusion; Surface Roughness

A method of combined method between the molecular dynamics and the discrete dislocation distribution method in the crack tip has been proposed in order to evaluate the macro characteristics of fracture toughness from micro characteristics of atomistic potential and the meso characteristics of critical resolved shear stress. And the method has been applied to the fracture toughness of the single crystal of W and NaCl, and it has been found from the results that the present method can estimate the ductile-brittle transition quantitatively from the micro and meso charactestics and moreover the strength criteria is very simple, the meso characteristics which control the micro-scale boundary condition of crack tip is very important. Therefore the in-situ observation system has been developed in order to evaluate the characteristics experimentally. Using this system, the mechanism of striation formation has been clarified. Based the mechanism, the evaluation method for fatigue limit characteristics has developed from the meso-characteristics. Namely, the method means that which can evaluate the influence of non-metallic inclusion and surface roughness. In the method, the statistic expression of the inclusion and surface configuration, the statistic expression of meso-scale material properties, and the quantitative expression for influence of micro notch and crack on fatigue limit are used. As the results of comparison between the predicted value and experimental one, it has been found that the proposed method is valid for the strength of materials.

本文提出了一种将分子动力学方法与裂尖离散位错分布方法相结合的方法，以便从原子势的微观特征和临界分辨剪应力的细观特征来评价断裂韧性的宏观特征。并将该方法应用于单晶W和NaCl的断裂韧性，结果表明，该方法能从细观和微观特征定量地评价韧脆转变，且强度判据简单，控制裂纹尖端细观边界条件的细观特征是非常重要的。因此，在现场观测系统已被开发，以评估的特性实验。利用这一系统，条纹的形成机制已被澄清。基于这一机理，从细观特征出发，发展了疲劳极限特性的评价方法。也就是说，该方法可以评估非金属夹杂物和表面粗糙度的影响。该方法采用夹杂物和表面形貌的统计表达式、细观材料性能的统计表达式以及微观缺口和裂纹对疲劳极限影响的定量表达式。通过与实验值的比较，表明该方法对材料的强度是有效的。

项目成果

Y.Oda, Y.Furuya, H.Noguchi, K.Higashida: "AFM and SEM Observation on Mechanism of Fatigue Crack Growth in an Fe-Si Syngle Crystal"International Journal of Fracture. 113. 213-231 (2002)

Y.Oda、Y.Furuya、H.Noguchi、K.Higashida：“AFM 和 SEM 对 Fe-Si 合成晶体中疲劳裂纹扩展机制的观察”国际断裂杂志。

宮崎達二郎, 野口博司, 大城桂作: "応力制御下における任意のき裂を有する金属の疲労限度の定量的評価"日本機械学会論文集A編. 68巻673号. 1352-1359 (2002)

Tatsujiro Miyazaki、Hiroshi Noguchi、Keisaku Oshiro：“应力控制下具有任意裂纹的金属的疲劳极限的定量评估”日本机械工程学会会刊，第 68 卷，第 673 期。1352-1359（2002 年） ）

宮崎達二郎, 野口博司, 大城桂作: "応力制御下における任意のき裂を有する金属の疲労限度の定量的評価"日本機械学会論文集(A編). 68巻673号. 1352-1359 (2002)

Tatsujiro Miyazaki、Hiroshi Noguchi、Keisaku Oshiro：“应力控制下具有任意裂纹的金属的疲劳极限的定量评估”日本机械工程师学会汇刊（ed. A），第 673 卷。1352-1359。 (2002)

T.Miyazaki, H.Noguchi, M.Kage: "Evaluation for Notch Effect in Fatigue Limit Reliability of High Strength Steels from Meso-Scale Characteristics"Transactions of the Japan Society of Mechanical Engineers. 69-678. 373-381 (2003)

T.Miyazaki、H.Noguchi、M.Kage：“从细观尺度特征评估高强度钢疲劳极限可靠性中的缺口效应”日本机械工程师学会汇刊。

Y.Oda, Y.Furuya, H.Noguchi, K.Higashida: "AFM and SEM Observation on Mechanism of Fatigue Crack Growth in a Fe-3.2% Si Single Crystal"International Journal of Fracture. Vol.113. 213-231 (2002)

Y.Oda,%20Y.Furuya,%20H.Noguchi,%20K.Higashida:%20"AFM%20and%20SEM%20观察%20on%20机构%20of%20疲劳%20裂纹%20生长%20in%20a%20Fe-3.2%