Abstract

To investigate the effect of basalt fiber on the fracturing process and damage mechanism of cement-based materials under axial compression, acoustic emission (AE) signals associated with basalt fiber reinforced mortar (BFRM) with 5 kinds of volume content (0–2.0%) under axial compression were recorded. The statistical analysis of wavelet energy spectrum coefficient and wavelet decomposition coefficient was carried out after threshold de-noising and noise evaluation of original signals by discrete wavelet transform (DWT) based on Mallat algorithm. Results show that the axial compressive strength and the acoustic emission activities decrease with the increase of fiber content. During the fracturing process of basalt fiber reinforced mortar under axial compression, the major energy frequency band concentrates on ca7 (seventh decomposition layers, 0–19.5 kHz), cd5 (fifth decomposition layers, 78–156 kHz) and cd4 (fourth decomposition layers, 156–312.5 kHz) bands corresponding to the wavelet transform. The wavelet energy spectrum coefficient of ca7 and cd4 bands shows distinct phased characteristics, which can be used to identify the damage degree, while the sudden increase in that of cd6 band can serve as a final failure precursor of the specimen. The variation of wavelet energy spectrum coefficient of ca7 and cd4 bands can be used to evaluate the crack resistance of basalt fiber. The maximum wavelet decomposition coefficient and the number of wavelet decomposition coefficient can be used to identify the degree of damage. The statistical analysis of wavelet energy spectrum coefficient and wavelet decomposition coefficient provides an innovative idea for evaluating internal damage of cement-based materials.

中文翻译：

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基于声发射小波能谱分析的玄武岩纤维砂浆破坏机理的实验研究

摘要

为了研究玄武岩纤维对水泥基材料在轴向压缩下的破裂过程和破坏机理的影响，与5种体积含量（0-2.0％）的玄武岩纤维增强砂浆（BFRM）相关的声发射（AE）信号在轴向压缩下记录。在基于Mallat算法的离散小波变换（DWT）对原始信号进行阈值降噪和噪声评估后，对小波能谱系数和小波分解系数进行统计分析。结果表明，轴向抗压强度和声发射活性随纤维含量的增加而降低。在玄武岩纤维增强砂浆在轴向压缩下的压裂过程中，主要能带集中在ca7（第七分解层，0-19.5 kHz），cd5（第五分解层，78-156 kHz）和cd4（第四分解层，156-312.5 kHz）频带对应于小波变换。ca7和cd4谱带的小波能谱系数显示出明显的相位特征，可用于识别损伤程度，而cd6谱带的突变突然增加可作为样本的最终破坏先兆。ca7和cd4带的小波能谱系数的变化可用于评价玄武岩纤维的抗裂性。最大小波分解系数和小波分解系数的数量可用于识别损伤程度。