Experimental Study on the Temporal and Morphological Characteristics of Dynamic Tensile Fractures in Igneous Rocks
Experimental Study on the Temporal and Morphological Characteristics of Dynamic Tensile Fractures in Igneous Rocks
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火成岩动态拉伸断裂时相和形态特征的实验研究
DOI：
10.3390/app112311230
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发表时间：
2021-12-01
影响因子：
2.7
通讯作者：
Yu, Qi
中科院分区：
文献类型：
--
作者：
Xu, Xuan;Chi, Li-Yuan;Yu, Qi
为了研究动态拉伸断裂的时间和形态特征，利用分体式霍普金森压力棒（SHPB）对由火成岩（角砾岩和安山岩）加工而成的巴西样品进行了实验。通过高速摄像机以每秒 10 万帧的帧速率对巴西标本的断裂过程进行详细观察。两种火成岩的动态拉伸强度的速率相关效应通过培育时间标准进行拟合和预测。采用数字图像相关（DIC）计算断裂前加载阶段试样表面的全场拉伸应变分布，并通过引入孕育时间的概念来解释动态断裂相对于应力水平的滞后现象。主裂纹出现后，利用图像处理技术提取高速图像中裂纹的像素信息。然后，FracPaQ 通过用断裂痕迹填充裂纹的二值化来量化碎片过程的形态。协调这些断裂痕迹的统计信息后，代表其角度和长度权重的玫瑰图可以直观地代表巴西标本的破碎特征。具体来说，各时刻断裂痕迹的长度-角度分布与高斯函数一致，曲线拟合参数反映了两种火成岩断裂行为的差异。总之，对两种火成岩动态劈裂过程中的动态断裂特征进行了统计量化，可为相关研究提供参考。
In order to investigate the temporal and morphological characteristics of dynamic tensile fractures, experiments on Brazilian specimens machined from igneous rocks (Breccia and Andesite) are carried out with the split Hopkinson pressure bar (SHPB). Detailed observation of the fracture processes of the Brazilian specimens is captured by high-speed camera at a frame rate of 100,000 frames per second. The rate-dependent effect of the dynamic tensile strength of the two igneous rocks is fitted and predicted by the incubation time criterion. Digital image correlation (DIC) is used to calculate the full-field tensile strain distributions on the specimen surface during the loading stage preceding fracture, and this hysteresis of dynamic fracture relative to stress level is interpreted by introducing the concept of incubation time. After the main crack appears, image processing technology is exploited to extract the pixel information of cracks in the high-speed images. Then, FracPaQ quantifies the morphology of the fragmentized process by filling the binarization of cracks with fracture traces. After coordination of the statistical information from these fracture traces, the rose diagram representing their angles and length weights can visually represent the fragmentized characteristics of the Brazilian specimen. Specifically, length-angle distributions of fracture traces at various moments are consistent with the Gaussian function, and the curve fitting parameters reflect differences in the fracture behaviors between the two igneous rocks. In conclusion, the dynamic fracture characteristics of two igneous rocks in dynamic splitting processes are quantified statistically, which can provide references for relevant research.