共查询到19条相似文献,搜索用时 203 毫秒
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FRP复合材料拉伸过程的声发射特性实验研究 总被引:1,自引:1,他引:0
用声发射技术研究了FRP复合材料的拉伸损伤与断裂行为。宽带传感器记录了FRP复合材料试样在拉伸破坏过程中的声发射信号,运用声发射参数分析方法对单向FRP复合材料的声发射历程图进行分析,得出复合材料在拉伸过程中的损伤类型以及各损伤阶段所呈现出来的特性。用扫描电子显微镜(SEM)观察了试样的几种典型的损伤破坏断面,对比分析了不同类型的损伤机制。实验分析表明,拉伸过程中破坏机制对声发射信号的特征具有显著影响,不同损伤模式的信号频谱特征存在明显的差异。 相似文献
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研究了超高相对分子质量聚乙烯抵密度聚乙烯( PE-UHMW /PE-LD)单向层合板拉伸破坏过程中的声发射信号参数之间的相关性,并进行了主成分分析。结果表明,声发射参数间存在较强的相关性,其中[0]层合板(加载方向与纤维方向平行)持续时间和振铃计数之间相关系数达到0.976,[90〕层合板(加载方向与纤维方向垂直)振幅和振铃计数之间相关系数达到0.8。主成分分析显示[0]和[90]层合板第一主成分主要反映上升时间、持续时间等信号的时域特点,第二主成分主要反映峰值频率、频率重心等信号的频域特点。通过[90〕层合板声发射信号的主成分得分图,显示出界面裂纹产生、扩展和界面分离等不同损伤模式对应不同的主成分得分。 相似文献
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为了解凝结硬化期间的扰动对混凝土损伤的影响,对处于初凝至终凝阶段的混凝土进行了模拟扰动试验,全程采集了受扰混凝土受压破坏过程产生的声发射信号。通过比较不同试件的声发射特征参数,研究了不同受扰龄期的混凝土在单轴受压条件下的声发射特性,并基于水泥混凝土结构形成动力学对受扰混凝土损伤机理进行了分析。结果表明:扰动使混凝土内部产生了不同程度的损伤,其中凝结硬化中期的扰动对混凝土性能影响较大,使混凝土峰值应力降低25.1%,损伤度达到14.2%,临近初凝和终凝的扰动对混凝土影响较小;与基准混凝土相比,受扰试件在加载初期声发射能量释放率较小,声发射活跃区间出现在加载后期。对于凝结硬化中期受扰的混凝土试件,在相对应力水平小于50%时,未采集到明显的声发射信号,此试件其声发射速率参数a值最小,过程参数b值最大。 相似文献
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首先,利用声发射仪器对石灰岩样品进行声发射断铅试验来获取声发射信号;然后,用小波变换对获取的声发射信号进行去噪处理,并用互相关方法对去噪后的信号进行分析,求取各个传感器之间的时差;最后,通过最小二乘法求取声发射源坐标,并将定位结果与仪器自带的定位结果进行比较。通过比较。得出了互相关方法在声发射源定位这一领域的可行性。 相似文献
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《玻璃钢/复合材料》2021,(8)
针对碳纤维增强复合材料(CFRP)损伤机制复杂、损伤声发射信号识别困难的问题,本文提出了一种基于模态分离方法的CFRP损伤信号识别分类算法,可实现CFRP损伤声发射信号的模态表征。首先,基于CFRP层合板模拟声源模态分析结果设计不同范围的数字滤波器,实现了声发射信号中的S_0、A_0模态分离;随后,根据纤维断裂和基体开裂单一损伤信号的模态特征,建立了损伤信号的识别分类算法,并验证了其对单一损伤信号的分辨率;最后,利用算法对层合板面内弯曲损伤信号进行分析,验证其在CFRP完整结构损伤信号识别中的有效性。结果表明,该算法在纤维断裂和基体开裂试验中的分辨率分别高达97.3%和92%,同时也实现了CFRP层合板的损伤过程表征,证明其可实现CFRP完整结构损伤机制的识别。 相似文献
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Conclusions A machine making it possible to simultaneously record strain and acoustic emission curves in bending of corundum refractories has been developed. It is shown that the Kaiser effect is not observed for CZ and MZ refractories with loads close to failure, which is the result of significant damage of the material in the preceding loading. The characteristic features of the strain curves of CZ and MZ refractories determined by recording of the acoustic emission process were established.Translated from Ogneupory, No. 4, pp. 15–19, April, 1986. 相似文献
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以聚乙烯(PE)塑料为研究对象,采用声发射监测技术对不同拉伸速度下试样失效过程进行监测,采集相应的声发射信号(持续时间、幅值、事件计数、撞击次数等),通过相关性系数分析确定评价因子,利用三角形隶属函数确定各评语集的失效隶属度,建立了PE塑料失效破坏程度主成分分析(PCA)模糊预测评价模型。另取同型号PE试样进行不同速度拉伸损伤破坏试验,并对损伤过程“力–时间”曲线的弹性阶段、屈服阶段(轻微失效)、颈缩阶段(中度失效)、断裂阶段(严重失效)特征点参数进行统计,破坏过程中所选时间点对应的失效程度与PCA预测评价结果一致,验证了模糊预测评价模型的可行性。 相似文献
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Junjie Yan Wen Yan Yajie Dai Guangqiang Li Xiao Wang Yucheng Yin 《International Journal of Applied Ceramic Technology》2023,20(6):3647-3655
The effect of spinel powder on the fracture behavior and mechanical properties of lightweight magnesia-based refractories containing microporous magnesia aggregates with high apparent porosity (37.4%) were investigated by the wedge splitting test (WST) with the digital image correlation and acoustic emission. With the addition of spinel powder, lightweight magnesia spinel refractories showed a higher cold compressive strength compared with lightweight pure magnesia refractories. From the WST, the addition of spinel powder increased the specific fracture energy and characteristic length of lightweight magnesia spinel refractories, which improved the crack propagation resistance. The increased tortuosity of main crack and a higher ratio of crack propagation along the aggregates/matrix interface were main reasons for reducing the brittleness of lightweight magnesia spinel refractories. Besides, acoustic emission (AE) signal activity indicated that the propagation of pregenerated micro-cracks by the thermal mismatch and the development of fracture progress zone were primary ways to consume energy in lightweight magnesia spinel refractories. The reduced proportion of crack propagation within aggregates was also detected by the peak frequency of AE signals in lightweight magnesia spinel refractories. For microporous magnesia aggregates with high apparent porosity (37.4%), lightweight magnesia spinel refractories also showed reduced brittleness fracture behavior than lightweight pure magnesia refractories. 相似文献
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Krzysztof J. Konsztowicz Denise Fontaine 《Journal of the American Ceramic Society》1990,73(10):2809-2814
Acoustic emission (AE) technique was applied to continuously monitor property degradation during standard thermal shock fatique testing of three distinct types of refractories. AE results were correlated with respective strength losses of analyzed materials after a defined number of heating and cooling cycles. The complex nature of the AE signals was revealed by AE amplitude and duration analysis indicating that not all of the signals that were registered during thermal shock tests could be correlated with strength changes. On this basis, it was postulated that simple counting of a number of AE events should not be used as a measure of the degree of damage in refractories under thermal shock. 相似文献
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通过对碳纤维编织复合材料的拉伸实验,利用声发射技术(Acoustic Emission,简称"AE")和数字图像相关(Digital Image Correlation,简称"DIC")方法研究碳纤维复合材料的损伤演化规律。通过采集试件在拉伸过程中的声发射信号、损伤变形与应变场信息,分析碳纤维编织复合材料的力学加载、变形场和声发射特征参数的关系。结果表明复合材料的位移场、应变场信息以及AE信号特征参数能良好地描述复合材料在拉伸状态下的损伤累积和破坏过程。在加载前期,以40~60 dB低幅度信号为主;随着载荷增加,撞击累计数急剧升高,高幅度、高持续时间信号增多。通过DIC测得的位移场和应变场信息,发现对于相同的载荷增量,加载方向的位移和最大拉应变呈先增加后减小的趋势。 相似文献
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《Journal of the European Ceramic Society》2014,34(7):1673-1679
This paper proposes a new approach to the analysis of acoustic emission data. The energy of acoustic emission signals recorded at two sensors is used to evaluate real-time energy attenuation due to damage accumulation. The method is applied to acoustic emission data recorded during static fatigue tests at intermediate temperatures on ceramic matrix composites. The evaluation of energy attenuation appears as a new indicator for damage monitoring and lifetime prediction, the attenuation increase being attributed to transverse matrix cracks opening. 相似文献
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《Ceramics International》2019,45(11):13847-13858
The damage mechanisms of carbon fiber reinforced silicon carbide (C/SiC) composites under static loading are investigated using the acoustic emission technology. The C/SiC sample is subjected to compressing static load, and acoustic emission is used to monitor the cracking process. In addition, the digital image correlation technique is also applied to enhance the comprehension of the damage mechanisms of C/SiC composites. To evaluate their extent of damage, the main acoustic emission characteristic parameters and indexes are extracted. The k-means clustering method is used to analyze the acoustic emission (AE) signals, identify the three damage modes, and determine the central values of the AE parameters of these modes. The time–frequency energy of some typical signals is analyzed by using the wavelet packet transform. Thereafter, the damage evolution is described by analyzing the cumulative number of acoustic emission events and the cumulative energy change with loading time. Moreover, the digital imaging results show that the strain in the structure increases with the increase in loading magnitude, especially in the area around the fault zone, where the strain level is evidently higher than those in other locations. Accordingly, this necessitates effective methods for investigating damage in C/SiC composites. Among the two different technologies implemented in this work, the extraction of AE events at several stages of the test allows the classification and analysis of crack evolution in C/SiC structures; this technique also provides an effective methodology to monitor the damage at the microscopic scale. 相似文献
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运用声发射检测技术,对Unipol气相流化床中声发射信号沿床高的规律性变化进行考察,对声信号进行复杂性分析,提取信号的涨落复杂性及Lempel-Ziv复杂性作为特征参数,成功获得了工业流化床中的颗粒流动模式。对声发射信号进行能量分析和复杂性分析均发现,Unipol工业气相流化床中的流型是带有滞留区的双循环流动模式。研究结果表明,基于复杂性分析和声发射检测的流化床中流型的测量是可行的。 相似文献