声发射信号分析及其软件实现

针对声发射检测技术的相关理论,基于VC++与PCI-2数据采集卡,设计了一套声发射信号采集、分析与处理系统,介绍了硬件和软件结构。该系统实现了数据采集、处理、显示及存储等功能,并能通过强大的Matlab接口对信号进行频谱分析。同时,提取了信号的幅值等20多种参数,并重点对振铃计数集质心频率等特征参数进行数据分析。最后,在实验室条件下分别用断铅信号和标准信号进行测试,验证了系统的可靠性。     

基于声发射检测的罐底腐蚀安全评估

常压储罐一旦发生泄漏,往往会造成人员伤亡、财产损失和环境污染等严重后果,因此对于储罐的安全评估尤为重要。现有的检测方法存在耗时长、易漏检、经济效益低等不足之处。以实例说明了声发射在线检测技术应用于罐底腐蚀检测的高可靠性与便捷性;解释了机械噪声、环境噪声以及电磁噪声形成的原因,并提出了相应的滤除方法;描述了基于声发射检测的罐底腐蚀安全评估的过程与评价依据,并进行评估。     

20~#钢拉伸过程的声发射信号频率特性分析

采用声发射(AE)测试技术对20#钢试件拉伸过程的声发射特性和声发射信号频率特性进行研究。得到不同拉伸阶段声发射信号幅值和累积撞击计数的变化规律,可以用来描述不同的拉伸阶段。声发射信号峰值频率具有较好的统计分布规律,可反映不同拉伸阶段的声发射信号频带分布特性。双谱分析方法更适合于声发射信号频率特征的识别,得到不同拉伸阶段声发射信号的双谱分布特征。     

模式识别在复合材料声发射信号分析中的应用

模式识别在复合材料声发射信号分析中的应用已初见成效。本文从信号的除噪与信号源的识别两方面综述了这一领域的研究,重点论述了特征的选取和模式识别方法的选择,并提出了目前研究中尚存在的一些问题及其展望。     

基于Hilbert-Huang变换的玻璃纤维自增强塑料声发射信号分析

简述了Hilbert-Huang变换(Hilbert-Huang Transform,HHT)的基本原理和利用其进行玻璃纤维自增强塑料(Glass Fiber Reinforced Plastics,GFRP)声发射信号分析的理论依据,并通过对实际信号的处理,很好地区分出不同破坏阶段的声发射信号的时频特征。研究结果表明,Hilbert-Huang变换能够有效保留源信号的固有特征,并且在自适应性以及时频聚集性上比其他时频分析方法有更大的优势,具有良好的局部化和结果直观性。     

304控氮不锈钢应力腐蚀过程中声发射信号聚类分析

研究了304控氮不锈钢试样在酸性氯化钠溶液中慢应变速率拉伸过程的声发射特征.采用基于自组织映射神经网络和K-均值聚类算法对长时间慢拉伸实验的声发射信号进行聚类分析,通过分析各类信号的持续时间、上升时间、振铃、能量、幅值、波形、频带能量等特征,从中找出了裂纹信号.将分类后的信号作为样本训练神经网络,对短时间慢拉伸实验检测...     

常压立式储罐底板腐蚀过程声发射源特性分析及试验研究

介绍了常压立式储罐底板腐蚀声发射信号产生的机理,研究了断铅声发射信号在罐内水中的衰减规律,分析了腐蚀声发射信号在不同传播介质中的特征参量取值范围及腐蚀规律。提取并对比分析了放入水中的传感器在不同腐蚀阶段接收到的信号波形特性,为常压立式储罐的腐蚀状态安全性评价提供依据。     

常压储罐罐底腐蚀声发射检测去噪方法分析

从声发射检测过程实施、检测仪器设置和信号处理3个方面来分析声发射检测去噪技术,旨在提高罐底声发射在线检测的可靠性和准确性,为工程实际检测提供一定的指导和借鉴意义。     

酸性NaCl溶液中304控氮不锈钢腐蚀过程的声发射特征

采用声发射技术和电化学噪声技术研究了304控氮不锈钢C型环试样在0.5mol·L-1NaCl与1.5mol.L-1H2SO4的混合溶液中,恒载荷情况下的腐蚀过程。分析了腐蚀过程中所产生的声发射信号的振铃数随时间分布情况,以及不同阶段的声发射信号的频谱特征。同时对比分析了声发射检测结果与电化学噪声检测结果。结果表明,声发射检测技术对于304控氮不锈钢在酸性NaCl溶液中所产生的腐蚀声发射信号很敏感,在不同腐蚀阶段中,声发射信号特征差异明显,对于判断不同腐蚀阶段具有指导意义;声发射与电化学噪声测试结果基本一致,将声发射检测与电化学噪声检测结合使用,有助于使现场检测结果更加可靠。     

X80管线钢在格尔木土壤模拟溶液中的耐腐蚀性能

采用失重法、电化学测试、SEM及XRD微观分析等方法,研究了X80管线钢在格尔木土壤模拟溶液中的耐腐蚀性能。结果表明,在格尔木土壤模拟溶液中,随着浸泡时间的增加,X80钢平均腐蚀速率明显下降,但腐蚀趋势增加,钢基体表面由以全面腐蚀为主转为以点蚀为主;X80钢的阴极反应为氧的去极化;腐蚀产物主要由FeOOH（表层）和Fe₃O₄（内层）组成;X80钢的耐蚀性及腐蚀形态与各试样表面生成的腐蚀产物膜的完整性和致密性有关。研究还发现氯离子含量是影响腐蚀的主导因素。     

基于平稳性能不确定信息盲源信号提取的过程监控方法

针对工业过程中的信息不一定平稳,提出了一种基于平稳性能不确定信息盲源信号提取的过程监控方法,并利用该方法提取过程盲源信号,采用k-近邻法进行分类,从而实现对过程性能的监控.通过对简单AR(1)过程和双效蒸发过程的仿真研究表明,这种方法是可行的.为了与基于传统独立成分分析(ICA)和多元统计过程控制(MSPC)的过程监控方法相比较,还作了相应的对比研究.结果表明,该方法比基于传统ICA的过程监控方法具有更少的误报率和漏报率,而比基于MSPC的过程监控方法具有更少的误报率,从而说明了该方法不仅是可行的,而且是有效的.     

Detection of SCC on prestressing steel wire by the simultaneous use of electrochemical noise and acoustic emission measurements

Electrochemical voltage and current noise were measured simultaneously with acoustic emission (AE) measurements during the stress-corrosion cracking (SCC) of prestressing steel wire. Elongation of the specimens was also measured. Constant load tests were performed on specimens made from prestressing steel with a diameter of 3.2 mm: the central wire of a seven-wire strand was used. The specimens were exposed to diluted sodium thiocyanate (a modified version of the test as proposed in EN ISO 15630-3), with and without the addition of an organic corrosion inhibitor. EN was measured between the stressed central cold-drawn wire and the neighbouring wires which acted as reference electrodes for the electrochemical current and voltage measurements. AE was measured by two AE sensors fixed to the specimen.In order to characterize the SCC processes on the prestressing steel wire, the results of all the used techniques were analysed and compared. The effect of the inhibitor on these processes was also studied. A significantly longer time to failure was observed in the experiments with the added inhibitor. The results of the techniques, in combination with SEM and metallographic inspections, confirmed that the inhibitor had a specific influence on SCC. It was concluded that measurements of combined methods are promising for the reliable detection of SCC.     

Presentation of a novel sensor based on acoustic emission in injection molding

Injection molding is the most important process to produce plastic parts. Because of increasing complexity of the plastic parts and the aim to reach zero‐defect production it is a must to control the dynamic injection molding process. Therefore information from the inside of the mold, measured with sensors, is necessary. State of the art is to implement wired mold cavity pressure sensors as well as wired cavity temperature sensors. This article presents a novel wireless measurement setup which uses structure borne sound as transport medium. The sound is generated by an acoustic actor which is activated by the passing flow front at certain predetermined positions in the cavity (or cavities). Beside the mechanical setup of the sensor proof of concept measurements with a prototype setup are shown in this article. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

基于吸引子比较法的卧式搅拌床反应器声发射故障诊断

在卧式搅拌床反应器丙烯聚合工艺中,结块是严重影响装置长期稳定运行和产品质量的隐患之一。本文以时域分析的角度,提出了一种基于吸引子比较法的声发射结块检测技术。该方法通过比较当前状态与正常状态的声发射信号,并借助统计量S值对两个时间序列的分布进行检验,从而判断两者是否由同一机理产生。当S<3时,则表明当前状态为正常;当S>3时,则表明反应器内有95%的可能性发生了结块。冷模实验结果表明,在合理选择传感器位置的前提下,通过对原始声发射信号进行消噪、归一化等预处理后,吸引子比较法能够灵敏地检测出卧式搅拌床反应器内粒径分布的细微变化,继而预警结块的发生。     

基于声发射监测的岩石水压致裂实验研究及数值模拟分析

采用岩石破坏过程渗流-应力耦合分析软件,考虑岩石岩性、节理裂隙状态、注水孔形状及大小、岩石强度、密度、渗透率及加载方式等影响因素,模拟研究了岩石水压致裂过程中的岩石损伤演化过程及破裂规律.同时结合室内物理实验和水压致裂数值模拟,对两种条件下的模拟实验结果及其应力—应变曲线进行对比分析,揭示了岩石水压致裂过程的裂隙岩体失稳规律,得出深部矿井采动渗水和突水过程中,覆岩裂纹起裂、扩展、渗水、突水,失稳破裂的全过程规律,数值模拟结果和实验结果具有较好的一致性,对矿山防治突水灾害有一定的理论指导意义.     

Modern concept of acoustic emission (AE) coupled with electrochemical measurements for monitoring the elastomer-coated carbon steel damage in phosphoric acid medium

Elastomer coatings (rubber) are industrially used to protect phosphoric acid storage tanks against corrosion. Rubber constitutes a barrier against the penetration of H₃PO₄ to metallic surface. Coatings damage induces both acid infiltration and steel corrosion. In this concept, acoustic emission (AE) monitoring technique could be used for the detection of coatings damage as well as for steel corrosion under the coating. In the present work AE was coupled to electrochemical measurements (EM) for rubber damage evaluation and steel corrosion on three types of steels (XC48, E20 and A60) at room temperature in concentrated phosphoric acid (30% P₂O₅) contaminated by Cl⁻, F⁻, SO₄²⁻. Electrochemical behaviour of steels was studied and characterized by potentiodynamic curves and polarization resistance measurement. A good correlation between acoustic emission and polarization resistance or corrosion potential measurements was found during stages of coatings damage and steels corrosion. The majority of AE activity recorded during experiments is related to hydrogen bubbles release. The release of hydrogen bubbles gives rise to two populations of signals: one impulsive and another one resonant.     

X80管线钢多功能耐高温暂时性涂层防护研究

制备了适用于X80管线钢的高温防护多功能暂时性涂层,并对其防护机理进行了分析。该新型防护涂层在1250°C下可使X80管线钢高温表面氧化烧损降低40%以上,同时有效降低了氧化铁皮的脱除难度。EDX面扫描分析结果表明,新型防护涂层改善了氧化层的致密层结构,提高了外层致密层占氧化层总厚度的百分比,弱化了底层致密层的富硅性能。多功能暂时性涂层的研究和应用将为我国X80管线钢的生产工艺革新和产品合格率的提高提供有益的借鉴。     

基于声发射能量的尾砂胶结充填体损伤演化模型

尾矿胶结充填广泛应用于矿山管理采空区的生产活动中,也是实现绿色开采和安全生产的主要技术之一。本文基于声发射技术对尾砂胶结充填体进行了循环加载和卸载试验,分析了加载过程中声发射能量的演化趋势,定义了基于声发射能量的损伤变量,建立了基于声发射能量的尾砂胶结充填体损伤演化方程,探索了声发射能量与损伤能量释放率之间的定量关系。为矿区胶结充填体承载过程分析和失效预测提供了基础研究依据。