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首页> 外文期刊>International Journal of Coal Science & Technology >Acoustic emission activity in directly tensile test on marble specimens and its tensile damage constitutive model
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Acoustic emission activity in directly tensile test on marble specimens and its tensile damage constitutive model

机译：大理石试样直接拉伸试验中的声发射活性及其拉伸损伤本构模型

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摘要

For understanding acoustic emission (AE) activity and accumulation of micro-damage inside rock under pure tensile state, the AE signals has been monitored on the test of directly tension on two kinds of marble specimens. A tensile constitutive model was proposed with the damage factor calculated by AE energy rate. The tensile strength of marble was discrete obviously and was sensitive to the inside microdefects and grain composition. With increasing of loading, the tensile stress–strain curve obviously showed nonlinear with the tensile tangent modulus decreasing. In repeated loading cycle, the tensile elastic modulus was less than that in the previous loading cycle because of the generation of micro damage during the prior loading. It means the linear weakening occurring in the specimens. The AE activity was corresponding with occurrence of nonlinear deformation. In the initial loading stage which only elastic deformation happened on the specimens, there were few AE events occurred; while when the nonlinear deformation happened with increasing of loading, lots of AE events were generated. The quantity and energy of AE events were proportionally related to the variation of tensile tangent modulus. The Kaiser effect of AE activity could be clearly observed in tensile cycle loading. Based on the theory of damage mechanics, the damage factor was defined by AE energy rate and the tensile damage constitutive model was proposed which only needed two property constants. The theoretical stress–strain curve was well fitted with the curve plotted with tested datum and the two property constants were easily gotten by the laboratory testing.
机译：为了解纯拉伸状态下岩石的声发射（AE）活性和岩石内部微损伤的积累，在两种大理石样品的直接拉伸试验中对AE信号进行了监视。提出了一种拉伸本构模型，其损伤因子由声发射能量速率计算。大理石的拉伸强度明显离散，并且对内部的微缺陷和晶粒组成敏感。随着载荷的增加，拉伸应力-应变曲线明显呈非线性，且拉伸切线模量减小。在重复加载循环中，拉伸弹性模量小于先前加载循环中的拉伸弹性模量，因为在先前加载过程中产生了微损伤。这意味着在样品中发生线性减弱。 AE活动与非线性变形的发生相对应。在初始加载阶段，仅在样品上发生弹性变形，几乎没有发生AE事件。当非线性变形随着载荷的增加而发生时，会产生大量的声发射事件。 AE事件的数量和能量与拉伸切线模量的变化成正比。在拉伸循环载荷中可以清楚地观察到AE活性的Kaiser效应。基于损伤力学理论，通过声能能定义损伤因子，并提出了仅需两个特性常数的拉伸损伤本构模型。理论应力-应变曲线与测试基准线绘制的曲线非常吻合，并且通过实验室测试很容易获得两个特性常数。

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