金属裂纹扩展声发射信号特性研究

发布时间：2019-05-14 11:21

【摘要】：机械结构件中的应力集中使得结构极易产生裂纹并逐渐扩展,裂纹扩展时伴有声发射信号,因此有必要对结构件中裂纹扩展时的声发射信号进行特征研究。为研究金属板件中的裂纹声发射源特征行为,通过分析板件中的裂纹声发射源,从理论上推导了裂纹声发射的幅值和频率特征表达式。在裂纹扩展过程中,金属板件的裂纹声发射信号幅值与声发射源的开裂长度和拉伸应力的乘积成正比,频率与裂纹开裂速度成反比,且与裂纹开裂长度成正比。用声发射检测系统对预制有初始裂纹的金属板件进行拉伸状态下的声发射监测,通过对声发射信号求取功率谱密度估计,实现不同声发射信号以功率谱在频域的分布为信号特征的有效区分。实验结果与理论分析相符合,研究结果对金属板件的裂纹声发射检测技术具有重要意义。
[Abstract]:The stress concentration in the mechanical structure makes it easy to produce cracks and gradually expand, and the crack propagation is accompanied by acoustic emission signals, so it is necessary to study the characteristics of acoustic emission signals during crack propagation in structural parts. In order to study the characteristic behavior of crack acoustic emission source in metal plate, the amplitude and frequency characteristic expressions of crack acoustic emission are derived theoretically by analyzing the crack acoustic emission source in metal plate. In the process of crack propagation, the amplitude of crack acoustic emission signal is proportional to the cracking length of acoustic emission source and the product of tensile stress, the frequency is inversely proportional to the crack cracking speed, and the crack cracking length is proportional to the amplitude of crack acoustic emission signal. The acoustic emission monitoring of prefabricated metal plate with initial crack is carried out by acoustic emission detection system, and the power spectral density is estimated by calculating the acoustic emission signal. The effective distinction between different acoustic emission signals is realized, which is characterized by the distribution of power spectrum in frequency domain. The experimental results are in good agreement with the theoretical analysis, and the research results are of great significance to the acoustic emission detection of cracks in metal plates.
【作者单位】：西安建筑科技大学机电学院;
【基金】：陕西省自然科学基金项目(2012JM7015) 长安大学道路施工技术与装备教育部重点实验室开放基金(310825161107)
【分类号】：TG115

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