类岩石材料破裂声发射的光纤光栅传感监测技术

针对岩石破裂声发射检测中的常规检测仪器抗电磁干扰差、灵敏度低、可靠性差等不足,提出采用光纤光栅传感技术来实现声发射检测,分析了光纤光栅传感检测应变和声发射的机理,组建了相应的声发射检测模拟实验系统,给出了模拟实验的500kHz激励声信号和光纤光栅传感响应信号。利用软件RFPA进行了岩石破裂的数值模拟,选择水泥河砂作为主要原料的砂浆材料,制作了类岩石材料实验试件,并在单轴数控压力机上进行了岩石试件加载破裂声发射实验,用光纤光栅传感器来探测和记录声发射能量及声发射累计次数,证明该传感器能实现声发射检测。     

基于光纤传感技术的机械量测试方法

光纤传感技术在制造业中应用越来越广泛。应用数字光纤检测技术对机床电机振动和内螺纹检测进行了技术分析。应用高频电子调制光纤检测技术,改善了振动测试的动态响应;应用中频电子调制,在内螺纹检测中降低了噪声和抑制了直流漂移。研究表明:光纤传感技术具有频率响应高、测量精度高、抗电磁干扰能力强的优点,是解决机械量测量的有效手段,在机械工程测试领域具有广泛的应用前景。     

熔锥耦合型光纤声发射传感器系统及其应用

介绍了基于熔锥耦合技术的光纤声发射传感器和系统。系统响应频率为20～180kHz,有效峰值灵敏度为-55dB ref 1V／μbar。使用该系统实现了对局部放电超声信号的有效测量。光纤传感具有本质安全,抗电磁干扰等优点,在高电压强磁场环境下工作可实现高灵敏度、长期稳定的远程监测,该系统有望在电力变压器局部放电在线监测中得到应用。     

基于强度型光纤传感技术的复合材料薄板损伤声发射定位法

声发射具有对缺陷起始和扩展探测灵敏的特点,适用于复合材料薄板损伤检测,其中定位方法的研究是关键技术之一。文章结合光纤传感技术,设计并构建了声发射检测系统,实现了复合材料薄板的损伤源定位。基于三角定位原理,进行分布式光纤传感布置,在复合材料薄板上方获取损伤信号。然后将测得的信号依次利用DaubechieslO小波和Gabor小波进行背景去噪和信号峰值提取,从而获得损伤源释放的AO模态兰姆波传播到各个传感器的精确时间。最后由到达时间依据三角损伤定位算法建立非线性方程组,通过计算即可求出损伤源位置。相比其它方法,该方法具有非接触、无需测量对象材料参数的优点,在复合材料薄板损伤检测应用中有重要意义。     

刀具磨损传感检测

本文除了简单介绍功率传感检测技术和力传感检测技术之外,详细介绍了目前最先进的刀具磨损检测技术——声发射(AE)检测技术。采用AE技术可达到高价刀具损耗最小,装刀、补刀停机时间最短和利用更先进的切削刀具提高加工效率的日的。     

光纤传感技术及其在管道监测中的应用

管道安全关系到人类生命和财产安全,及时掌握管道结构健康状态是确保其安全运行的重要前提,近年来发展起来的光纤传感技术为管道结构的安全监测提供了技术保障。传感器的选择和使用是进行结构监测时首先考虑的问题,重点介绍了SOFO点式、FBG准分布式、BOTDR和BOTDA分布式光纤传感器等光纤传感技术的系统组成、基本原理及关键技术,对其性能和特点进行了对比分析;在此基础上,探讨了适用于管道变形监测的FBG和BOTDA光纤监测实用系统,及适用于管道泄漏监测的基于拉曼散射的OTDR分布式温度传感技术和基于模态分布调制干涉技术的油气管道检测系统。分析了其各自作为结构监测传感器的优缺点,为今后的管道监测选用提供了依据。     

声发射技术在阀门检漏中的应用

提出采用声发射技术检测阀门的泄漏，介绍了声发射检测原理、声发射传感器的制作方式以及信号处理方式。试验和实际检测证明，采用声发射技术检测阀门的泄漏是可行的，检测简便、快捷、准确，扩大了声发射技术的应用范围，有效地监控了阀门的泄漏状况。     

声发射研究用的非接触式传感器

与常用压电声发射能器不同，声发射研究中使用的非接触式宽带传感器主要有两种，即电容传感器和光学探测器，为了削弱孔径效应，空气间隙的电容传感器采用了不同的结构。光学探测器则是建立在激光干涉的基础上，利用偏振干涉方法研制的光学探测器是传感器的一种优化设计，而光纤传感器在实现声发射技术的现场应用中有许多潜在的优点。     

声发射检测技术在齿轮故障诊断中的研究与应用现状

归纳了常见的齿轮故障类型,介绍了声发射技术的齿轮检测和监测原理,综述了声发射技术在齿轮故障检测中的研究与应用,包括机理研究、运行条件对声发射信号的影响以及声发射信号处理技术,着重分析了各种信号处理方法在齿轮箱故障诊断中的研究情况,并指出了声发射技术在齿轮故障诊断研究中的潜在问题和下一步研究方向,以为同行提供参考。     

风机叶片连接螺栓损伤的在线监测

综述了先进的螺栓结构连接监测技术,介绍了振动信号检测技术、声弹性效应技术、压电效应检测技术、光纤传感技术和基于材料及结构特征检测方法等的风机连接螺栓在线监测技术的研究进展,分析了这些技术的特点及其在风机螺栓松动监测中的适用性。     

泄漏声发射传感器的标定研究

介绍了声发射传感器标定原理及几种常用标定方法的模拟声源的特性。提出了将比较法应用于管道泄漏检测的声发射传感器的标定。建立了基于脉冲表面波声场的声发射传感器标定系统，对商用和自制的几种声发射传感器进行了标定。标定结果和探头使用效果证明，比较法标定声发射传感器是可行的。     

光纤网络用于检测复合材料结构状态的实验研究

提出一种采用埋入式光纤传感器无损检测复合材料结构状态的新方法。将两种结构简单的新颖光纤传感网络埋入飞机的层状复合材料垂直尾翼试件,对结构内应变、应力以及由于低频部冲击造成的损伤等状态参数进行检测,实验结果显示了该方法的可行性。     

声发射检测中的压电换能器

在声发射检测中，传感器是获取信息的关键部件之一。目前绝大部分声发射传感器都是压电换能器。就采用压电原理的声发射传感器的发展及其校准问题作概述，对声发射传感器中的特殊问题孔径效应及其对传感器设计、性能和校准的影响进行讨论。     

Fiber optic sensors in concrete: the future?

Fiber optic sensing systems have been successfully developed for many engineering applications. The objective of this review paper is to assess the potential of fiber optic sensors for the monitoring of concrete structures. In this paper, some current applications of fiber optic sensors in concrete structures are first reviewed to demonstrate their applicability in conventional monitoring applications. The advantages of optical sensors over electrical gauges and transducers are also discussed. Then, we will focus on two novel fiber optic sensors for the monitoring of cracking and delamination in concrete structures without requiring a priori knowledge of the damage locations. Through these two examples, it is demonstrated that the proper design of optic sensors can provide useful sensing capabilities unprecedented with conventional sensors. With further research focusing on the development of novel sensing concepts and the reduction of sensor cost, the widespread use of optical sensors in concrete structures can become a reality in the future.     

NDE of smart structures using multimode fiber optic vibration sensor

There are many conventional methods which may be used to monitor the health of structures — of which vibration monitoring is effective and can be used for special structures such as aircraft wings. A smart structure system based on fiber optic vibration sensors has been developed to monitor structural damage. A method based on the detection of spatial speckle of a multimode optical fiber is described. A multimode optical fiber with a diameter of 200/230 μm is used in the present experiment. The theoretical analysis and the experimental tests are described. The fiber optic sensors have been embedded in the carbon/epoxy composite specimens and surface mounted on the surface of aluminum specimens. Furthermore, experiments to examine the different types of damage to these specimens have been carried out. The results show that this kind of multimode fiber optic sensor can be used in the non-destructive evaluation of smart materials.     

Monitoring of corrosion in reinforced concrete structure using Bragg grating sensing

Corrosion in reinforced concrete structures is a major problem that seriously affects the service life of the structures. In order to detect rebar corrosion, a fiber optic corrosion sensor (FOCS) made of one fiber Bragg grating (FBG) sensor and twin steel rebar elements was designed and packaged up with concrete. Subsequently, a series of experiments were carried out to verify its feasibility. A constant current accelerated corrosion test was performed on five fiber optic corrosion sensors and the relationship between reflected wavelength change from the grating and the weight loss rate of rebar was obtained by the gravimetric weight loss method. The experiment shows that it is feasible to monitor the degree of corrosion of reinforced steel in reinforced concrete structures using FOCS.     

声发射源多传感器数据融合识别技术研究

波形数字声发射技术的发展给声发射源的特性识别带来了可能。噪声的影响和声发射信号传播过程的复杂性给声源的识别带来一定的困难。为了解决干扰情况下声发射源的定性问题，提出了在决策层上的多传感器数据融合的识别方法。利用定位传感器组中各个传感器得到的数据，同时考虑在同一个定位组中各个传感器所得数据的置信度不同，来对声发射源性质进行识别。实验结果证明，数据融合后声发射源特性识别的可靠性明显大于单个传感器，表明了多传感器融合识别的可能性和有效性。     

A self-calibrating piezoelectric transducer with integral sensor for in situ energy calibration of acoustic emission

Piezoelectric transducers are used as both transmitters and sensors in acoustic emission (AE) testing applications. However, the transducer outputs are significantly affected by the coupling between the transducer and the structure. This means that the coupling must be very carefully controlled or assessed if reliable AE calibration sources are to be generated, and be considered in the AE system calibration if reliable AE measurements are to be made. The paper shows that by integrating a piezoelectric AE sensor to the backing of a conical piezoelectric transducer acting as the transmitter, a self-calibrating AE energy point source can be obtained. There is a negative linear relationship between the AE signal energy from the backing sensor and the coupling efficiency for a constant electrical input to the transmitter over the frequency range of interest in AE measurements (100 kHz to around 1 MHz). This should enable the strength of the simulated AE point source to be determined using the AE measurement from the backing sensor, and hence to facilitate in situ energy calibration of AEs in structures.     

传感器阵列对岩体微震/声发射源定位精度的影响（英文）

随着开采深度增加,岩体动力灾害日益突出。微震监测已成为岩爆、顶板坍塌等岩体动力灾害监测的重要技术手段。传感器阵列布设作为信号采集的第一步,严重影响信号源的定位精度。讨论和总结有关由传感器阵列布设引起的微震(MS)和声发射(AE)震源定位误差的重要研究,并分析传感器数量、传感器布设形态以及传感器与震源距离对MS/AE源定位精度的影响机制。随后,结合工程实践和实验室测试,给出传感器阵列的一些布设原则,并通过现场应用进行验证。另外,综合考虑影响传感器阵列布设数量、形状和距离的因素,找到最优布置方案,可大幅度改善信号采集效果,提高信号源定位精度。最后,对提高MS/AE源定位精度所面临的挑战和传感器阵列方面相应的应对策略进行展望。