共查询到17条相似文献,搜索用时 187 毫秒
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声发射(AE)技术能用来区分发生在受载材料内的不同损伤模式,而聚类分析能在无先验知识的情况下通过揭示数据内部结构对数据进行分类。声发射波形包含了丰富的声发射源信息,而常规的特征参数并不能满足深层次的声源识别要求。文章尝试从波形的频率分布特征、形状特征和强度特征三个方面分别选取小波变换能量特征系数、波形裕度因子和幅值作为描述声发射波形的新参数。基于波形新参数的聚类分析能有效地区分加氢反应器材料2.25Cr-1Mo带裂纹和无裂纹试件拉伸过程中屈服阶段塑性变形信号、微裂纹扩展信号和断裂失稳信号。 相似文献
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采用声发射(acoustic emission,AE)技术对7N01铝合金单边缺口三点弯曲试样不同应力比、不同峰值载荷下疲劳裂纹扩展过程中声发射信号进行了监测,建立了裂纹扩展速率、声发射计数(count)与应力强度因子之间的关系.结果表明,大部分的声发射信号主要产生于疲劳循环载荷的低应力阶段,这主要是低应力阶段的声发射活动主要与裂纹尖端的塑性变形和裂纹闭合现象有关,声发射计数与应力强度因子之间呈指数增长的关系.基于所建立的声发射计数率与裂纹扩展速率的关系,可以预测疲劳损伤结构的剩余寿命. 相似文献
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Investigation of acoustic emission signals under a simulative environment of grinding burn 总被引:2,自引:0,他引:2
Qiang Liu Xun Chen Nabil Gindy 《International Journal of Machine Tools and Manufacture》2006,46(3-4):284-292
Grinding burn is a common phenomenon of thermal damage that has been one of the main constraints in grinding in respect of high efficiency and quality. An acoustic emission (AE) technique was tried in an attempt to identify grinding burn on-line. However, the AE features of grinding burn are relatively weak and are easily obscured by other AE sources. This paper presents an investigation of the AE features of the thermal expansion induced by laser irradiation, which was designed to simulate grinding thermal behaviour. By using wavelet packet transforms, AE features at the grinding burn temperature can successfully be extracted without other mechanical interferential factors. Such thermal AE features provide a firm foundation for analysing and monitoring the AE features of grinding burn. 相似文献
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基于HHT的预应力钢筋混凝土梁断裂AE信号分析 总被引:2,自引:0,他引:2
针对混凝土材料损伤所产生的声发射信号复杂的特点,提出了基于Hilbert—Huang变换的分析混凝土声发射信号的新方法。利用全波形声发射技术记录了预应力混凝土梁在三点弯曲荷载试验下整个破坏过程的声发射信号,研究了声发射累计能量随时间变化的关系曲线,分析了梁在不同破坏阶段产生的实测声发射信号,获得了信号的Hilbert谱。通过与小波分析结果进行比较,显示出该方法具有处理精度高、自适应性强的特点,能有效地提取声发射信号中损伤的主要特征,为声发射信号处理提出了一种新的途径。 相似文献
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在20℃至-55℃下对16MnR材料进行Charpy冲击试验,用声发射技术监测各温度下冲击开裂的过程。采用小波分析结合傅里叶变换的方法,得到了16MnR试样开裂过程的波形频谱特性及电压幅值,并且采用金相和SEM对冲击断口进行了组织、形貌分析。结果表明:随着温度的下降,声发射计数率、声发射能量及声发射持续时间均呈降低趋势,声信号幅值变化不大。小波分解后的d2层能量包含冲击断裂的主要能量,与冲击功的变化趋势相似,具有较强的相关性。试验结果为声发射技术监测冲击载荷作用下的材料内部结构演化提供了一个思路。 相似文献
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声发射检测的主要目的是发现声发射源和有关源的信息,声发射源定位是声发射检测中至关重要的指标,其准确程度反映了声源的检测位置与实际缺陷源位置的符合程度。本研究针对复合材料的特性,结合实际情况进行了声速和衰减测量实验,并通过断铅实验对复合板进行声发射定位。通过对复合材料板压缩实验的在线监测,基于声发射信号参数的提取及关联图分析,给出了各损伤阶段的参数特征,以及声发射监测区域内的裂纹萌生扩展断裂的时间和位置。研究结果表明,复合板实际断裂位置与声发射监测得出的位置相吻合。 相似文献
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Jian-nong Jing Li-hong Dong Hai-dou Wang Guo Jin 《Journal of Thermal Spray Technology》2018,27(7):1090-1102
Plasma-sprayed coatings are widely used in industry, e.g., in applications subject to high wear and corrosion damage, or requiring thermal insulation. However, the failure behavior of such coatings has a great influence on the service safety of mechanical parts. Acoustic emission (AE) has attracted much attention due to its proven usefulness for real-time monitoring of damage evolution and high sensitivity to fracture sources. In this study, the damage evolution behavior of a plasma-sprayed coating subjected to three-point bending fatigue tests was monitored using the AE method. A method combining parameterized, Fourier, and wavelet analysis was used to distinguish the damage modes in the coating. The analysis results revealed two crack modes (surface vertical crack and interface crack) with two different peak frequencies. A finite element method was used to quantify the fracture stress and propagation behavior of cracks, revealing that the thickness of the coating had a strong influence on its spalling. 相似文献