Crack-fabrication techniques and their effects on the fracture toughness and CTOD for fresh-water columnar ice
Crack-fabrication techniques and their effects on the fracture toughness and CTOD for fresh-water columnar ice
复制标题
淡水柱状冰裂纹制造技术及其对断裂韧性和CTOD的影响
作者：
Y. Wei;S. Defranco;J. Dempsey
摘要：采用6种不同方法制作6组具有不同裂纹（或缺口）根半径的单边缺口弯曲（SENB）试样，研究了缺口锐度（裂纹尖端锐度）对S2冰断裂韧性的影响。钝切口试件的表观断裂韧性值K Q的平均值和标准差均显著高于尖锐裂纹试件。结果显示在断裂韧性对比图中，其中p是裂纹尖端半径，提供了断裂韧性测试所需缺口敏锐度的估计。裂纹尖端附近的显微组织特征和裂纹尖端的几何形状决定了冰的表观断裂韧性的大小。本研究测量的裂纹尖端张开位移（CTOD）表明，在不稳定断裂开始时，裂纹尖端附近存在微塑性变形。
Abstract The effects of notch acuity (crack-tip sharpness) on the fracture toughness of S2 ice were investigated using six groups of single-edge-notched-bend (SENB) specimens with different crack (or notch) root radii fabricated by six different methods. The mean value and standard deviations of the apparent fracture-toughness values K Q of the specimens with blunt notches were significantly higher than those of the specimens with sharp cracks. The results presented in a plot of fracture toughness versus , where p is the crack-tip radius, provide an estimate of the required notch acuity for fracture-toughness testing. The microstructural features in the immediate vicinity of the crack tip and the crack-tip geometry govern the magnitude of the apparent fracture toughness of the ice. The crack-tip-opening-displacement (CTOD) measured in this study indicates the existence of microplastic deformation in the vicinity of the crack tip at the initiation of unstable fracture.