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

分叉的弹塑性分析及其在小裂纹疲劳门槛值分析中的应用分叉：采用切向塑性框架下的切向-次加载面模型，给出了不可压缩圆柱在轴对称载荷作用下局部分叉和扩散分叉的解析解。分析包括剪切带形成的条件，剪切带的倾斜，扩散屈曲的形成，以及扩散屈曲模式的长波长和短波长限制与材料性能和应力的关系。它成为消息灵通的正常屈服比描述的程度接近正常屈服状态，切向塑性应变率由于切向应力率效应和运动硬化变量的影响发病的本地化和扩散bifurcations.Fatigue和断裂：在混合模式下加载的钝裂纹尖端的弹塑性区的表征进行了讨论。出现在裂纹前端的变形区描述提出了一个标准的基础上的次加载面的概念属于非常规塑性的框架内。结果表明，复合型裂纹沿着弹塑性区的最小值扩展，并对有限裂纹附近斜面上位错的行为进行了研究.基于有限裂纹与裂纹尖端位错之间的相互作用，给出了力的表达式。利用扩展方程研究了裂纹长度对位错受力的影响。

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.