摘要
本文采用四点弯曲试件考察了常用韧性材料16MnR钢中Ⅰ-Ⅱ复合型裂纹的断裂机理。实验测定了裂纹扩展方向和裂纹尖端位移参量的启裂值；与此同时，采用有限元程序计算了试件中复合型裂纹尖端邻域的应力、应变场，分析了各种控制空洞成核的力学参量的几何分布曲线，结合实验研究和有限元分析表明，Ⅰ-Ⅱ复合型断裂存在两种不同的断裂机理，它们的发生取决于Ⅰ-Ⅱ复合型载荷比的大小，当Ⅱ型载荷分量小于一临界值时、断裂为张开型．裂纹扩展方向与本文的бm峰值线准则一致；而当Ⅱ型载荷分量大于此临界值时，断裂表现为不稳定的剪切型断裂。
In this paper, the fracture behaviour of Ⅰ-Ⅱ mixed mode crack of a low carbon alloy steel, 16MnR. was studied. The crack propagation angle and the components of crack tip opening displacement vectors were determined experimentally. Meanwhile. the stress -strain fields in the vicinities of Ⅰ-Ⅱ mixed mode crack tip were calculated with elastic -plastic F. E. M.. The distribution of void nucleation parameters was analysed. Combined with the experimental observation and F. E. M. analysis, it was shown that there were two types of mechanisms in Ⅰ-Ⅱ mixed mode fracture. When the ratio or mode Ⅱcomponent is smaller than a threshold value, the fracture is an opening type and the propagation direction coincides well with that predicted by the бm. peak value line,when the ratio of mode Ⅱ component is greater, the fracture is a shearing type which is a fast and unstable slip process along the original crack surface in the role of the maximum shearing stress.
出处
《压力容器》
1997年第2期9-13,共5页
Pressure Vessel Technology
