声发射技术在储罐检测中的应用

介绍了声发射检测技术的基本原理和特点,通过100m^3液化气储罐声发射检测的应用实例,说明了声发射检测的实施过程和结论分析,因其具有简捷、经济、灵敏度高,又能检测“动态”缺陷等特点,已发展成为金属压力容器检测和安全评定的主要无损检测方法之一。     

多层包扎式尿素合成塔的声发射检测与评定

采用声发射监测方法,并结合其他检测方法对多层包扎式尿素合成塔进行检测和结构完整性评价。检测结果表明,声发射检测技术不仅适用于单层压力容器,而且也同样适用于多层包扎高压容器的检测与安全可靠性的评定。     

声发射技术在压力容器检验中的应用探讨

由于压力容器的特殊工作环境,要求压力容器在应用中具备更高的安全标准,如果压力容器的安全标准不达标,就可能引起重大安全事故。故此,压力容器的安全的检测就变得十分重要。声发射技术属于一种无损检测技术,具有精度可靠,适应范围广的特点,应用到压力容器的检测,可提升压力容器的安全等级。本文主要介绍声发射技术的原理,优势与特点,以及声发射技术在压力容器检验过程中的应用。     

基于声发射技术的储罐无损检测

声发射技术是一种先进的无损检测技术,广泛应用于储罐的无损检测。文中阐述了声发射检测技术的基本原理和特点,根据某石化厂油料储罐底板有油渗漏但未查到泄漏点的情况,采用声发射技术对该储罐底板损伤进行了无损检测。结果显示,缺陷声源定位与实际查到的泄漏位置仅相差0.2m,效果较好;根据检测结果制定出储罐合理的维修策略和安全的使用压力。     

压力容器无损检测——声发射检测技术

压力容器无损检测技术是现代社会中应用的新型检测技术,这种检测措施通过外部检测,获得压力容器的内部检测成果。声发射检测技术是现代无损检测技术中的一种形式,在生产检测中得到广泛应用。结合现代工业生产技术检测的实际应用,对压力容器无损检测技术中的声发射检测技术进行分析。     

第十二届全国声发射学术研讨会征文通知

第十二届全国声发射学术研讨会征文通知经第十届无损检测学会声发射专业委员会决定,由南京市锅炉压力容器检验研究院承办的第十二届全国声发射学术研讨会,初定于2009年7月30日在江苏省南京市举行,现在全国范围内征集有关声发射技术的研究及应用论文。一、征文范围(1)声发射技术     

储罐底板腐蚀检测技术对比试验研究

通过对比15台储罐的声发射检测和漏磁检测结果,确定声发射检测结果和漏磁检测结果有很好的一致性,验证了声发射检测技术对储罐底板腐蚀状态评价的可靠性。对储罐进行声发射检测,根据检测结果对严重等级高的储罐进行开罐检测,对科学保障储罐的安全运行具有重要意义。     

钛复合钢板多层包扎容器腐蚀泄漏后的检测与评定

本文论述了内筒为复合钛板的多层包扎式压力容器因钛层被冲蚀形成腐蚀空洞并造成腐蚀穿孔后如何进行无损检测和安全评定的问题。着重介绍了针对多层筒壁内腐蚀空洞的无损检测方法以及钛层下腐蚀缺陷的无损检测方法的试验研究。在试验研究的基础上确定了可行的检测方案。同时论述了腐蚀空洞类缺陷的安全评定方法。这种非常规的检测与评定方法对众多的在用多层包扎并有防腐衬里的容器有可以借鉴的共性。     

压力容器无损检测——声发射检测技术

声发射检测技术在20世纪70年代得到初步发展,经过多年的发展与完善,已成为现阶段比较成熟的一种无损伤检测方法,并广泛地应用于压力容器检测与压力容器结构完整性的评价方面。首先简要介绍了国内压力容器声发射检测的发展历程,对压力容器声发射检测技术的发展做出相关概述;其次,说明声发射检测技术的应用原理与应用优势;最后,重点阐述压力容器无损检测中声发射技术的应用流程。     

声发射技术在压力容器检验当中的应用价值分析

压力容器在制造过程中需要焊接的部位非常多,且由于工作环境的恶劣,容易出现腐蚀、裂纹,对压力容器的使用性能造成影响,导致引发安全事故。为了确保生产安全,需要采用有效的检验方法对使用中的压力容器进行定期检验,避免安全事故的发生,本文主要针对声发射技术在压力容器检验中的应用价值进行分析。     

A comparative experimental study on the use of acoustic emission and vibration analysis for bearing defect identification and estimation of defect size

Vibration monitoring of rolling element bearings is probably the most established diagnostic technique for rotating machinery. The application of acoustic emission (AE) for bearing diagnosis is gaining ground as a complementary diagnostic tool, however, limitations in the successful application of the AE technique have been partly due to the difficulty in processing, interpreting and classifying the acquired data. Furthermore, the extent of bearing damage has eluded the diagnostician. The experimental investigation reported in this paper was centred on the application of the AE technique for identifying the presence and size of a defect on a radially loaded bearing. An experimental test rig was designed such that defects of varying sizes could be seeded onto the outer race of a test bearing. Comparisons between AE and vibration analysis over a range of speed and load conditions are presented. In addition, the primary source of AE activity from seeded defects is investigated. It is concluded that AE offers earlier fault detection and improved identification capabilities than vibration analysis. Furthermore, the AE technique also provided an indication of the defect size, allowing the user to monitor the rate of degradation on the bearing; unachievable with vibration analysis.     

基于声发射技术的点接触润滑状态研究

为研究点接触在部分弹流润滑条件下的润滑状态,使用球盘式摩擦磨损试验机进行试验,利用声发射技术监测不同工况下的润滑状态,并分析在不同工况下声发射信号特征参数的变化规律。结果表明:声发射信号特征参数计数、能量、信号强度对润滑状态的改变非常敏感,都随滑动速度的增加而减小,随载荷的增加而增加且在变化规律上几乎一致;利用声发射技术能够表征边界润滑向部分弹流润滑的过渡状态。     

机体飞行载荷疲劳试验中的声发射特性分析

机体飞行载荷疲劳试验是全尺寸飞机疲劳试验的最关键部分,主要目的是暴露机体结构疲劳薄弱部位和疲劳损伤关键部位,确定这些位置疲劳裂纹的扩展特征。论文介绍利用声发射技术对应力集中且可达性差的关键部位进行实时监控的细节,通过分析声发射特性,及时得到监测区域内裂纹萌生扩展的起始时间和位置的信息。详细叙述在高背景噪声环境下如何获取有用声发射信号的方法,包括使用谐振式传感器,采用空间滤波技术、基于统计平均的特征参数趋势分析和基于幅度的相关参数趋势分析的相互验证,以及采用载荷滤波、幅度滤波和空间滤波相结合的综合滤波方法。结果表明,这种声发射信号快速处理方法成功的实时监测到螺栓孔周围裂纹的萌生和扩展过程。     

A comparative experimental study on the diagnostic and prognostic capabilities of acoustics emission,vibration and spectrometric oil analysis for spur gears

Prognosis of gear life using the acoustic emission (AE) technique is relatively new in condition monitoring of rotating machinery. This paper describes an experimental investigation on spur gears in which natural pitting was allowed to occur. Throughout the test period, AE, vibration and spectrometric oil samples were monitored continuously in order to correlate and compare these techniques to natural life degradation of the gears. It was observed that based on the analysis of root mean square (rms) levels only the AE technique was more sensitive in detecting and monitoring pitting than either the vibration or spectrometric oil analysis (SOA) techniques. It is concluded that as AE exhibited a direct relationship with pitting progression, it offers the opportunity for prognosis.     

Effect of fuzzy C means technique in failure mode discrimination of glass/epoxy laminates using acoustic emission monitoring

Acoustic emission is one of the powerful techniques that can be used for in situ structural health monitoring of composite laminates. One of the main issues of AE is to characterize the different damage mechanisms from the detected AE signals. Unsupervised Pattern recognition has been one of the techniques used for the identification of a specific failure mode in composites from Acoustic emission data. Cross ply composite laminate of size 300 × 300 mm is fabricated using Vacuum bag molding. ASTM D3039 Standard tensile specimens are cut from the laminate and these specimens are subjected to uni axial tensile test under Acoustic Emission monitoring. Fast Fourier transform analysis (FFT) and Short Time Fast Fourier Transform (STFFT) analysis are performed on the Wave forms of the AE hit data obtained during the conduct of tensile test to characterize the failure modes in crossply specimens. Fast Fourier Transform enabled calculating the frequency content of each damage mechanism. In this paper Fuzzy C Mean clustering is performed for the AE parameters obtained from the test and the efficiency of this technique is being investigated using FFT AND STFFT analysis.     

Lead-free acoustic emission sensors

Acoustic emission (AE) sensors have been fabricated using both soft- and hard-type lead-free (Na0.5K0.5)NbO3-based ceramics. The acoustic and electromechanical properties of the ceramics have been determined using the resonance technique. The lead-free AE sensors were calibrated using a laser source and compared to a commercial sensor. A lead zirconate titanate (PZT) 5H ceramics AE sensor has also been fabricated and calibrated for comparison. It was found that the sensitivity of lead-free AE sensors is comparable to that of the lead-based PZT sensor. To evaluate the sensors for potential application, they have been used in the detection of AE in an impact test. The lead-free sensors can reproduce AE signals accurately without giving artifacts and have potential use in commercial AE systems.     

Acoustic sources from damage propagation in Ti grade 5

In this paper fatigue test results are presented for titanium grade 5 specimens subjected to uniaxial cyclic loads. The material behavior of titanium was studied by comparing the Acoustic Emission (AE) detection technique with the Infrared Thermography (IT). The AE technique consists on attaching a couple of piezoelectric sensors on the surface of the sample in order to allow real-time recording of acoustic activity occurring in the material during the test and to localize the acoustic source, based on the assumption that part of the acoustic activity depends on the crack propagation process. All typical data of AE were collected during the tests and some of them were properly post-processed by using filters or derivative functions in order to better understand the crack propagation phenomenon. At the same time, thermographic analysis was also carried out during the experiments by continuous monitoring of surface temperature of the sample. Results of the fatigue behavior of the analyzed material beside the acoustic emission track and the thermal images of the sample are analyzed and critically discussed, in order to assess the capability of each technique in predicting the imminent failure of material.     

1000 m3液化气球罐的声发射检测

采用声发射检测技术对10 0 0m3液化气球罐的上半球罐进行了声发射检测,并将声发射检测结果与常规磁粉探伤结果进行了比较,发现利用声发射方法检测出需要复查的区域与磁粉探伤结果具有较好的符合性。对今后关键压力容器的不开罐定期检验具有指导意义。     

滑动轴承接触摩擦故障的状态监测

滑动轴承的代表性故障是轴承与轴颈的接触摩擦故障，在试验台上采用从正常润滑状态逐步向干摩擦状态过渡的方法模拟故障，并利用声发射信号对滑动轴承的工作状态进行监测。结果表明，声发射技术用于滑动轴承的在线状态监测具有很多优越性。     

BK7光学玻璃金刚石划刻声发射信号的特征提取

以金刚石压头划刻BK7光学玻璃为研究对象,分析了脆性材料脆性去除过程中的声发射机制,研究了声发射信号的特征提取技术。多种切深实验显示:BK7光学玻璃发生脆性去除的特征主要集中在[100,200]kHz、[300,400]kHz两个频段,对应不同的声发射机制,其中[100,200]kHz频带的滤波信号呈现明显的、时间间歇的突发式声发射现象,与脆性材料裂纹的生成与扩展密切相关。基于上述实验结果,提出了以突发式声发射事件为单位的特征监测方法。针对该带通滤波信号的均方根值(RMS),研究了基于凸优化理论的声发射事件识别算法,得到了脆性材料裂纹扩展的时刻及能量信息。得到的结果表明:以声发射事件为单位的特征监测具有明确的物理意义,能够更加客观地表征脆性材料的去除过程。