摘要
通过大量４ＰＢ试样解理断裂力学和断口参数的统计，发现在缺口前端发生于峰值应力左侧的断裂几率大于右侧，并且随温度的降低发生于左侧的几率增加，解理起裂在离开缺口根部的一个最小距离处才能发生，在某一距离范围内断裂几率最大。通过对上述现象的分析提出缺口试样的解理断裂须满足两个条件，即缺口根部的塑性应变ε＿ｐ大于材料中薄弱环节的起裂塑性应变ε＿（ｐｃ），使解理微裂纹形核；最大正应力σ＿（ｙｙ）大于薄弱环节的解理强度σ＿ｆ，使微裂纹扩展。缺口试样的解理断裂有起裂控制的情形，基于新的断裂物理模型，分析了对起裂点位置的统计结果，以及材料微观断裂力学参数对断裂行为的影响。
In this investigation,by means of a statistics of a large number of fracture me-chanics and surface parameters of fracture mechanics and surface parameters of Notchedspecimens,it was found that the occuring probability of the fracture at the left side of themaximum stress location ahead of a notch root is larger than that at the right side and the oc-curing probability at the left side increases with decreasing temperatures.The initiation ofcleavage can only occur at a small distance from a notch root.With the increase of the dis-tance from a notch root,the fracture probability increases and at some distance it reachs amaximum value.By analyzing the facts described above,it was suggested that two condi-tions must be satistied for the cleavage fracturing in notched specimens,that is,the plasticstrain ε_p ahead of a notch root must be larger than a critical value ε_(pc) for initiating a microc-rack and the principal stress σ_(yy) must be larger than the local cleavage fracture stress σ_f for thepropagation of the microcrack. The cleavage fracture in notched specimens also has a situa-tion of initiation controlled. Based on a new cleavage fracture model,the statistical results ofthe location of initiating cleavage and the influence of the fractuse mechanics parameters onthe fracture behavior were analysed.
出处
《甘肃工业大学学报》
1994年第2期1-6,共6页
Journal of Gansu University of Technology
基金
甘肃省自然科学基金
关键词
焊缝
解理断裂
统计
缺口试样
weld,cleavage fracture,statistics,fracture model,notched specimen
