基于声发射数据的脆性材料损伤表征研究

发布时间：2019-05-14 02:49

【摘要】：在外力作用下仅产生很小的变形就发生破坏断裂的材料称为脆性材料,如岩石等。脆性材料受力达到一定程度时会突然发生破坏,这种突发的、没有预兆的破坏将会给工程带来严重的灾害,因此利用声发射技术对脆性材料损伤进行实时监测,研究其内部损伤破坏过程具有重要意义。岩体的稳定性受水分的影响很大,岩石受水浸湿后使岩石力学性质受到影响,导致岩石强度降低,塑性变形成份增加。含水岩石与干燥岩石的声发射规律有很大不同。同一试样饱和状态下的声发射特征和干燥状态下的声发射特征有较大差异,而且这种差异随着含水率的变化而变化。本文通过岩石的单轴压缩声发射试验,利用小波变换的方法对不同饱和度岩石的声发射信号进行处理,并用声发射参数的方法研究岩石的损伤表征。(1)根据小波变换的理论,研究利用小波变换对声发射信号的不同频带能量提取的方法；利用这种方法对不同饱和度的完整砂岩和有初始损伤砂岩的单轴压缩试验的声发射信号进行处理,提取各频带的信号的能量,通过分析各频带的能量得到能够表明声发射信号能量分布规律的特征频带和其声发射信号的主频带,并得到其声发射信号频带能量的分布规律。(2)对闪长岩单轴压缩的声发射试验的数据进行分析。首先分析闪长岩的声发射信号的特性：根据声发射信号的活动情况反映岩石整个破坏过程的损伤情况,分析损伤初期、损伤演化和失稳破坏各阶段的声发射信号的活动情况。其次利用小波变换的方法对闪长岩声发射信号进行处理,得到闪长岩的声发射信号能量主要分布频带。最后根据岩石损伤变量与应变和声发射参数的定量关系式,利用闪长岩声发射的相对能量累积计数与相应的应变的数据,通过MATLAB拟合得出闪长岩损伤变量D的公式以及其损伤的应力应变关系式,理论的损伤应力应变曲线与试验应力应变曲线比较吻合,验证了闪长岩损伤变量公式的准确性。
[Abstract]:Materials with small deformation and fracture under external force are called brittle materials, such as rocks and so on. When the force of brittle material reaches a certain degree, the damage of brittle material will suddenly occur. This kind of sudden and unforeseen damage will bring serious disaster to the project, so the acoustic emission technology is used to monitor the damage of brittle material in real time. It is of great significance to study the internal damage and failure process. The stability of rock mass is greatly affected by moisture. After the rock is soaked with water, the mechanical properties of rock are affected, which leads to the decrease of rock strength and the increase of plastic deformation composition. The acoustic emission law of water-bearing rock is very different from that of dry rock. The acoustic emission characteristics of the same sample in saturated state are quite different from those in dry state, and the difference varies with the change of moisture content. In this paper, the acoustic emission signals of rocks with different saturation are processed by wavelet transform through the uniaxial compression acoustic emission test of rocks. The damage characterization of rock is studied by the method of acoustic emission parameters. (1) according to the theory of wavelet transform, the method of extracting energy from different frequency bands of acoustic emission signal by wavelet transform is studied. The acoustic emission signals of complete sandstone with different saturation and uniaxial compression test with initial damage sandstone are processed by this method, and the energy of the signal in each frequency band is extracted. By analyzing the energy of each frequency band, the characteristic frequency band which can show the energy distribution law of acoustic emission signal and the main frequency band of its acoustic emission signal are obtained. The distribution of band energy of acoustic emission signal is obtained. (2) the data of acoustic emission test of diorite uniaxial compression are analyzed. Firstly, the characteristics of acoustic emission signal of diorite are analyzed: according to the activity of acoustic emission signal, the damage of rock in the whole failure process is reflected, and the activity of acoustic emission signal in each stage of damage evolution and instability is analyzed. Secondly, the acoustic emission signal of diorite is processed by wavelet transform, and the main energy distribution band of acoustic emission signal of diorite is obtained. Finally, according to the quantitative relationship between rock damage variables and strain and acoustic emission parameters, the relative energy accumulation count and the corresponding strain data of diorite acoustic emission are used. The formula of diorite damage variable D and its damage stress-strain relationship are obtained by MATLAB fitting. The theoretical damage stress-strain curve is in good agreement with the experimental stress-strain curve, which verifies the accuracy of the damage variable formula of diorite.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU45

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