动态断裂中的脆性/准脆性转变：一种能量特征
Brittle/quasi-brittle transition in dynamic fracture: An energetic signature
摘要：
动态断裂实验在PMMA在很宽的速度范围内进行，并揭示，断裂能表现出突然3倍的增加，从它的值在裂纹萌生在一个定义明确的临界速度，低于一个相关的发病的微支化不稳定。这种转变与断裂表面上的二次曲线图案的出现有关，在许多材料中，二次曲线图案是通过微裂纹的成核和生长而扩展的损伤的标志。一个简单的模型可以将能量和断口形貌测量相关联。这些结果表明，在非晶材料中，在低速下的动态断裂是由这里研究的脆性/准脆性转变控制。
英文摘要：
Dynamic fracture experiments were performed in PMMA over a wide range of velocities and reveal that the fracture energy exhibits an abrupt 3-folds increase from its value at crack initiation at a well-defined critical velocity, below the one associated to the onset of micro-branching instability. This transition is associated with the appearance of conics patterns on fracture surfaces that, in many materials, are the signature of damage spreading through the nucleation and growth of microcracks. A simple model allows to relate both the energetic and fractographic measurements. These results suggest that dynamic fracture at low velocities in amorphous materials is controlled by the brittle/quasi-brittle transition studied here.
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