塑性材料薄板复合断裂研究

Mixed mode fracture of the plastic sheet

从弹塑性断裂力学理论出发,分析了塑性薄板的纯Ⅰ型、纯Ⅱ型以及Ⅰ型-Ⅱ型复合裂纹稳定扩展的断裂性能。计算了复合裂纹稳定扩展时的裂纹尖端张开角Ψ,并尝试将其作为描述塑性薄板断裂韧性的参数;初步分析纯Ⅱ型以及Ⅰ型-Ⅱ型复合裂纹从裂纹尖端一侧启裂的原因。结果表明:(1)此类塑性薄板塑性变形很大,不易破碎,纯Ⅰ型裂纹扩展最难;(2)当裂纹稳定扩展时,临界裂纹尖端张开角Ψc趋于稳定,故裂纹尖端张开角可作为塑性薄板裂纹稳定扩展的断裂韧性参数;(3)裂纹前缘区域的应力较大,因此裂纹尖端的前缘部分更容易发生断裂。

Based on the theory of elastic-plastic fracture mechanics, analysed the fracture properties of modeⅠ,modeⅡand mixed-modeⅠ/Ⅱ crack during stable propagation of the plastic sheet. The CTOA of the mixed mode crack during stable propagation was calculated and tried to be used as the parameter to describe the fracture toughness of the plastic sheet. The reason of crack initiation appearing in the tip of mode 2 and mixed mode 1/2 crack was preliminarily analyzed..It is shown that:(1)The plastic sheet used in this study has very large plastic deformation and is not easy to break;Besides, the modeⅠcrack is the most difficult to propagate(2)The CTOA tends to be stable when the crack extension is steady, so it can be used as the fracture toughness parameter of the plastic sheet.(3) The stress in the crack front area of crack is larger, which makes the front area of crack tip more prone to fracture.