Criticality in failure under compression: Acoustic emission study of coal and charcoal with different microstructures
Criticality in failure under compression: Acoustic emission study of coal and charcoal with different microstructures
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压缩失效临界点：不同微观结构煤和木炭的声发射研究
DOI：
10.1103/physreve.99.033001
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发表时间：
2019
影响因子：
2.4
通讯作者：
Vives Eduard
中科院分区：
文献类型：
--
作者：
Xu Yangyang;Borrego Angeles G;Planes Antoni;Ding Xiangdong;Vives Eduard
对煤和木炭样品在缓慢单轴压缩下的声发射雪崩进行了系统的研究。样品表现出一系列的有机组成的化学元素，以及不同程度的异质性的微观结构。实验分析的重点是单个声发射事件的能量以及连续事件之间的时间相关性。所研究的样品可以分为三组。更均匀的样品（组I）与孔在微米和纳米尺度上，在应力-应变曲线的硬化效应的签名，表现出最干净的临界幂律行为的能量distributionwith临界指数。更异质的样品与空隙，大孔，和粒状微观结构（第三组），显示签名的削弱效果和更大的有效指数接近的值，但在某些情况下截断的指数阻尼因子。其余的样品（第二组）表现出混合交叉行为仍然兼容的有效exponent，但明显截断指数因子。这些结果表明，存在两种可能的普适性类压缩下的多孔材料的失败：一个均匀的样品和高度不均匀的样品。关于雪崩之间的时间相关性，所有的样本表现出非常相似的等待时间分布，虽然大森余震分布的一些差异不能被丢弃。
A systematic study of acoustic emission avalanches in coal and charcoal samples under slow uniaxial compression is presented. The samples exhibit a range of organic composition in terms of chemical elements as well as different degrees of heterogeneity in the microstructure. The experimental analysis focuses on the energiesof the individual acoustic emission events as well as on the time correlations between successive events. The studied samples can be classified into three groups. The more homogeneous samples (group I) with pores in the micro and nanoscales, with signatures of hardening effects in the stress-strain curves, exhibit the cleanest critical power-law behavior for the energy distributionswith a critical exponent. The more heterogeneous samples with voids, macropores, and granular microstructures (group III), show signatures of weakening effects and a larger effective exponent close to the value, but in some cases truncated by exponential damping factors. The rest of the samples (group II) exhibit a mixed crossover behavior still compatible with an effective exponentbut clearly truncated by exponential factors. These results suggest the existence of two possible universality classes in the failure of porous materials under compression: one for homogeneous samples and another for highly heterogeneous samples. Concerning time correlations between avalanches, all samples exhibit very similar waiting time distributions although some differences for the Omori aftershock distributions cannot be discarded.