材料の分岐変形に関する弾塑性変形解析と微小疲労き裂進展挙動解明への応用

分叉材料变形的弹塑性变形分析及其在阐明微疲劳裂纹扩展行为中的应用

• 批准号: 04F04078
• 负责人: 村上 敬宜
• 金额: $ 1.54万
• 依托单位: Kyushu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for JSPS Fellows
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04F04078/
• 关键词: Bifurcation and Instability; Elastoplasticity; Constitutive Behavior; Elastoplastic Materials; Subloading Surface Model; Crack tip Plasticity; Dislocation Mechanics; Mixed Mode Fracture; Shear Band; Bifurcation

Elastoplastic analysis of bifurcation and application to fatigue threshold analysis of small cracksBifurcation :Analytical solutions are presented for the localized and diffuse bifurcations of an incompressible circular cylinder subjected to axisymmetric loading, whose constitutive behavior is described by adopting the tangential-subloading surface model falling within the framework of tangential plasticity. The analysis includes the conditions for shear band formation, shear band inclination, diffuse buckling formation, and the long and short wavelength limits of diffuse buckling modes in relation to material properties and stress. It becomes well-informed that the normal-yield ratio describing the degree of approach to the normal-yield state, the tangential-plastic strain rate due to the tangential-stress rate effect and the kinematic hardening variable influence the onset of localized and diffuse bifurcations.Fatigue and Fracture :The characterization of the elastoplastic zone at the tip of a blunt crack under mixed mode loading was discussed. The deformed zone appearing at the crack front is described by presenting a criterion based on the subloading surface concept falling within the framework of unconventional plasticity. It is revealed that the mixed mode crack propagates along the minimum value of the elastoplastic region.A study was conducted to clarify the behavior of a dislocation located on the inclined plane near a finite crack. Equations were presented for the forces based on the interactions between a finite crack and the dislocations near the crack tip. The influences of crack length on the forces applied to a dislocation were investigated using the extended equations.

分岔的弹塑性分析及其在小裂纹疲劳阈值分析中的应用分岔：给出了轴对称载荷作用下不可压缩圆柱的局部分岔和扩散分岔的解析解，其本构行为采用切向塑性框架下的切向-次加载面模型来描述。分析了剪切带形成的条件、剪切带的倾角、扩散屈曲的形成以及扩散屈曲模式的长、短波长极限与材料性能和应力的关系。众所周知，描述接近正常屈服状态程度的正常屈服比、切向应力率效应引起的切向塑性应变率以及运动硬化变量影响局部和扩散分叉的发生。疲劳与断裂：讨论了混合模态载荷作用下钝裂纹尖端弹塑性区的特征。在非常规塑性框架下，提出了基于次加载面概念的判据来描述裂纹前缘出现的变形区。结果表明，混合模式裂纹沿弹塑性区最小值扩展。对有限裂纹附近斜面位错的行为进行了研究。提出了基于有限裂纹与裂纹尖端位错相互作用的力方程。利用扩展方程研究了裂纹长度对位错受力的影响。

项目成果

Crack tip plasticity in edge-blunt-cracked plates

边缘钝裂板的裂纹尖端塑性

• 发表时间: 2005
• 期刊: McMat2005, Baton Rouge, Louisiana, USA, June 1-3 Paper No.464
• 作者: Khojastehpour;M.;Murakami.Y.
• 通讯作者: Murakami.Y.

Elastoplastic zone and crack initiation in blunt-notched plates

钝缺口板的弹塑性区和裂纹萌生

• 发表时间: 2005
• 期刊: ICCES'05, Chennai, India, December 1-6 41
• 作者: Khojastehpour;M.;Murakami.Y;Hashiguchi.K.
• 通讯作者: Hashiguchi.K.

Localized bifurcation in soils with tangential plasticity

具有切向塑性的土壤中的局部分叉

• 发表时间: 2004
• 期刊: The 39th Japan National Conference on Geotechnical Engineering, Niigata, Japan, July 6-9
• 作者: Khojastehpour;M.;Hashiguchi.K.;Murakami.Y.
• 通讯作者: Murakami.Y.