FBG应变传感器的动态特性及其应用范围

通过对应变波的传播过程分析，研究了FBG（Fiber Bragg Grating）应变传感器的动态特性，给出了应变波传递到裸FBG上的滞后时间，估算了FBG应变传感器的最高工作频率，并将自行封装的FBG应变传感器粘贴于海底管线模型上进行了振动台试验，结果表明，FBG应变传感器适用于低频振动系统的监测需要，在对低频振动系统的监测中具有良好的工作性能。     

双光纤光栅高频加速度传感器的研究

研制了一种新型双光纤光栅加速度传感器,并对该传感器的工作原理和基本特性进行了理论分析,实测表明,这种新型双光纤光栅加速度传感器可在5?2000Hz频率范围内获得稳定的振动信号。这不仅解决了传统悬臂梁FBG加速度传感器难以实现高频振动测量的问题,而且具有温度自补偿、谐振频率高、使用方便等优点,在高频测量中具有广阔的应用前景。     

用于非线性兰姆波检测的高灵敏度宽带光纤光栅传感器

光纤传感器因其灵敏度高,已逐渐应用于超声检测的研究中,但大多数光纤传感器的频带响应范围有限,约为几百k Hz,很难检测到更高频率的信号。所提出的光纤布拉格光栅(Fiber Bragg Grating,FBG)传感器的高频检测范围可以达到4 MHz左右,大大提高了其检测带宽范围。文中将传感器应用于304不锈钢板兰姆波的非线性检测,同时与传统超声换能器的检测结果做对比。实验结果表明,用脉冲波激励信号时,FBG传感器可以检测到钢板兰姆波的基频到五倍频信号,表明FBG在检测兰姆波非线性上是有很大潜力的。     

光纤光栅传感器在CFRP冲击载荷监测中的应用研究

提出了一种用光纤光栅传感器监测CFRP结构冲击载荷的方法,构建了冲击监测系统。将FBG传感器粘贴于CFRP试件表面构成传感网络,针对不同冲击点,同一传感器监测的冲击响应信号进行分析,CFRP试件的一阶、二阶谐振频率为53 Hz、100 Hz,不同谐振频率对应的幅值随冲击点的改变而不同。冲击CFRP试件,对FBG传感网络感知的冲击响应信号进行小波包分解,获得各传感器的小波包能量谱图。结果表明传感器信号的第6阶小波包能量变化明显,能量大小与冲击点和传感器之间的距离及其夹角有关。研究结果将为CFRP结构的动态监测领域提供了实验参考。     

Pointwise fiber Bragg grating displacement sensor system for dynamic measurements

A method for setting up a fiber Bragg grating (FBG) sensor which can measure the pointwise, out-of-plane or in-plane dynamic displacement is proposed. The proposed FBG sensor is reusable. A multiplexing demodulation system based on a single long-period fiber grating is used in this study. The experimental results of the steady-state motion for a multilayer piezoelectric actuator and the dynamic response of a cantilever beam subjected to impact loadings are presented. These results indicate that the proposed displacement sensor has the ability to measure the out-of-plane dynamic displacement with high sensitivity. Measurements for a piezoceramic plate excited by high frequency show that the proposed displacement sensor also has the ability to provide the in-plane dynamic displacement up to 20 kHz.     

复合材料胶层光纤布格光栅应变监测优化配置研究

航空航天用复合材料粘接胶层在制造和服役过程中不可避免会产生各种缺陷和损伤。针对其粘接胶层缺陷和损伤检测,基于光纤光栅应变传感原理,提出一种针对复合材料胶接层结构应变监测的光纤光栅传感网络优化配置的方法。通过仿真和实验研究了埋入复合材料构件胶接层的光纤布拉格光栅传感器在静载作用下的敏感区域分布特性,分析了载荷位移与布拉格波长漂移的关系,建立符合光纤布拉格光栅传感器实际特点的探测模型,采用粒子群优化算法进行光纤光栅传感网络的优化布置,研究结果表明光纤布拉格光栅传感器位置经优化后,覆盖率得到明显提高。     

基于概率模型的光纤光栅传感网络优化布置

光纤光栅传感器相比与传统传感器,其特有的轴向敏感性决定了它的探测距离在传感器的不同方向上是有差异的,因此光纤光栅传感器的布置角度对于传感器网络的性能具有很大的影响。基于传统传感器的概率探测模型,本文提出了一种贴合光纤布拉格光栅传感器实际特点的探测模型,并通过实验验证了其正确性,继而利用这一模型,采用粒子群优化算法进行了光纤光栅传感网络的优化布置。最后,同不考虑布置角度的优化布置方法进行了比较,结果表明,在实际应用中考虑布置角度对于传感网络性能具有很大的提升。     

Absolute strain measurements made with fiber bragg grating sensors

A strain sensor system based on optical fiber Bragg gratings (FBGs) is proposed with a new matched-filter design. The strain variation on the sensor FBG is continuously followed and matched by a filter FBG by use of a feedback control loop that produces an identical strain condition on the filter FBG. The matched strain on the filter FBG is then determined from the resonance vibration of the fiber piece embedding the filter FBG. The implementation and the performance of the proposed system are described. It is demonstrated that the proposed system can distinguish strain variation on the sensor FBG with resolution of one microstrain.     

基于超磁致伸缩材料的FBG电流传感器温度特性研究

针对基于超磁致伸缩材料的FBG电流传感器,分析了温度对传感头各个部分和整个传感头的影响,通过试验研究了FBG、Fe—Ga超磁致伸缩棒以及传感头三个部分的温度特性。结果表明,FBG的温度特性为线性,Fe—Ga超磁致伸缩棒以及传感头的温度特性整体为非线性,Fe—Ga超磁致伸缩棒的温度响应大于FBG的温度响应,传感头的温度特性主要取决于Fe—Ga超磁致伸缩棒的温度特性。在26℃到60℃范围内,根据传感头的温度特性,可采取分段补偿的方法消除温度影响,将温度特性分为线性区和非线性区两个范围,分别得到了传感头温度特性拟合方程。     

FBG应变挠度法标定及过程仿真

介绍了一种基于挠度分析的等强度悬臂梁FBG传感器应变标定测试方法和装置,研究了FBG传感器应变传递过程中的相关参量的仿真分析方法,精确测量了应变传递过程中的相关参量,并且针对不同载荷下的等强度悬臂梁的表面应变和挠度进行了理论分析和仿真。同时解析了挠度与梁表面应变、FBG传感器应变的关系,给出了标定后FBG传感器的应变灵敏度,并对挠度法测量FBG传感器的标定结果进行了不确定度评定。当包含因子k=2时,FBG传感器应变灵敏度的相对扩展不确定度＜0.5％,能够满足高精度的应变测试要求,为高精度FBG传感器的应变标定提供了技术支持。     

High-Temperature Resistance Fiber Bragg Grating Temperature Sensor Fabrication

Fiber Bragg grating (FBG) temperature sensor and sensor arrays were applied widespread particularly in harsh environments. Although FBGs are often referring to permanent refractive index modulation in the fiber core, exposure to high-temperature environments usually results in the bleach of the refractive index modulation. The maximum temperature reported for the conventional FBG temperature sensor is around 600 degC due to its weak bonds of germanium and oxygen. In this paper, we report design and development of a novel high-temperature resistance FBG temperature sensor, based on the hydrogen-loaded germanium-doped FBG. The refractive index modulation in the FBG is induced by the molecular water. The results of our experiments have shown that the stability of the device is substantially increased at high temperature range. Due to the high bonds energy of hydroxyl and the low diffusivity of the molecular water, the thermal testing results of this temperature sensor show the thermal stability of hydrogen-loaded FBG can be increased by using annealing treatment; moreover, the highest erasing temperature for the device could reach to 1100 degC or more. The reflectivity of this new FBG depends on the concentration of Si-OH and indirectly related to the reflectivity of hydrogen-loaded FBG. Furthermore, the experimental results have provided a better understanding of the formation of the hydrogen-loaded FBGs and the chemical transfers at elevated temperatures in the fiber core     

光纤Bragg光栅用于高频应变测试的研究

提出了一种传感部分采用光纤Bragg光栅(Fiber Bragg grating,FBG)传感器的高频应变测试新方法.设计并构建了基于非平衡马赫-曾德(Mach-Zehnder)干涉仪的高频解调系统.完整的测试系统由FBG传感器、高频应变产生装置和解调系统三部分组成.所产生的应变信号的频率可以通过专门的实验装置来控制,这是一种广泛用于测试材料机械性能的变形分离式霍布金逊压杆(Split Hopkinson Pressure Bar,SHPB)实验装置,应变持续的时间根据与撞击弹性等径的冲锤长度计算.借助高频振动信号研究了测试系统可测信号的频率范围.给出了振动和冲击实验结果,并进行了讨论.所设计的系统可以实时测试动态应变的幅值,实验结果表明,该系统对频率为8kHz以下的信号具有好的响应.     

光纤Bragg光栅应变传感器在霍普金森压杆上的冲击试验研究

利用复合材料封装光纤Bragg光栅(FBG)设计制作了用于测量高速碰撞或爆炸与冲击作用下混凝土内部动态应变的FBG应变传感器。在霍普金森压杆上对FBG在封装前的裸光栅和封装后的FBG传感器分别进行了高速冲击试验,试验表明：设计的FBG传感器的瞬态响应上升时间小于20μs,具有良好的动态响应特性,可以用于工程中混凝土结构内高速冲击下的动态应变测试     

Performance comparison of Raman/erbium-doped-fiber hybrid-amplification-based long-distance fiber Bragg grating sensor systems

A study regarding the performance comparison of three different types of long-distance fiber Bragg grating (FBG) sensors based on bidirectional Raman and erbium-doped fiber (EDF) amplification has been carried out to determine the most power-efficient and accurate configuration. The three sensor system configurations studied were a bidirectional hybrid Raman amplifier with (Type I) an EDF located after the distributed Raman amplification section, (Type II) an EDF located before the distributed Raman amplification section, and (Type III) without an EDF. The FBG sensor systems are based on a demodulation scheme employing radio frequency power measurements of a beat signal, in which a sine-modulated amplified spontaneous emission from a directly modulated reflective semiconductor optical amplifier is employed as a broadband light source. The results of our experimentation showed that the sensor system with the EDF located prior to the Raman amplification section provided the best performance in regards to its pump power efficiency, electrical signal-to-noise ratio, and measurement accuracy.     

Fiber Bragg Grating Sensor System With Two-Level Ring Architecture

This investigation proposes a fiber Bragg grating (FBG) sensor system with a two-level ring architecture. The survivability and capacity of a FBG for a multipoint sensor system are enhanced by adding remote nodes and optical switches in the two-level ring architecture. Additionally, to enhance the signal-to-noise ratio (SNR) of the sensor system, a fiber ring laser approach is utilized to construct the proposed two-level ring architecture. The fiber ring laser adopted herein yields the high SNR of the sensor system. The proposed system can increase the reliability of FBG sensor systems for multipoint smart structures.      

基于长信号谱自相关的光纤光栅传感解调方法

针对光纤光栅传感领域波长高精度探测和传感复用光栅数量增多的需要,提出一种基于长信号相关谱的新型光纤光栅数字解调技术.该技术在可调谐滤波法的基础上,通过传感光栅与调制光栅反射谱卷积后的信号,即光电探测器的光强时间信号,进行自相关分析以实现对波长漂移的测量以及对传感光栅反射谱形状的识别,增强系统的复用能力,提高了性价比.模拟仿真表明,光纤光栅长信号相关数字解调方法可以准确测量光纤光栅波长的漂移,能更好实现传感复用.等强度悬臂梁实验验证该解调方法能实现光栅应变的高精度测量,优于传统的应变片测试.     

光纤布拉格光栅三维测头

介绍了一种以光纤布拉格光栅为传感元件的三维测头.测头结构核心为3根悬丝和支架组成的柔性支撑系统,传感系统由3根传感FBG和一根匹配FBG光栅组成.测头的关键参数测定结果为结构复位性精度小于20nm,传感系统重复性小于0.2mV,分辨力小于0.1μm,测力小于5mN.     

胶粘剂对表贴式FBG传感器应变传递系数的影响

利用光纤光栅（FBG）传感器对基体表面应变进行测量,通常利用胶粘剂将光纤光栅传感器粘贴在基体表面,使其与基体协调变形。但胶粘剂在不同表面的粘接性能不同,对应变测量所造成的影响也就存在差异。针对这一问题,本文通过实验,简化应变传递模型,对比FBG传感器粘贴在等强度梁以及标准树脂试件的应变测量结果。结果表明:胶粘剂在基体表面的剪切强度越大,表面粘贴式FBG传感器的应变传递系数也越大。      

Tracking control of a multilayer piezoelectric actuator using a fiber bragg grating displacement sensor system

This paper provides a fiber Bragg grating (FBG) sensor system which can measure the point-wise, out-of-plane displacement to examine the position-tracking control problem of a multilayer piezoelectric actuator (MPA). An FBG filter-based wavelength-optical intensity modulation technique is used in this study. A nominal system model is identified experimentally from the responses excited by random signals measured by an FBG displacement sensor that are simultaneously compared with those obtained from a laser Doppler vibrometer. To further investigate the sensing ability of the proposed system in a feedback control problem, control strategies including robust Hα control, proportional-integralderivative control, and pseudoderivative feedback control are implemented. The characteristics of the step responses for each controller are examined. The experimental results show that the proposed sensor system is capable of performing the system identification and can serve as a feedback control sensor which has a displacement sensitivity of 5 mV/nm.     

灵敏度可调型光纤FBG倾角传感器研究

提出了一种基于等截面梁弯曲变形原理的灵敏度可调型光纤布拉格光栅(FBG)倾角传感器,通过FBG光栅感受因结构倾角改变而引起的等截面梁弯曲变形,进而实现对结构倾斜角度的测量,并构建了灵敏度可调型光纤FBG光栅倾角检测系统。实验结果表明,该FBG倾角传感器测量范围为±35°,最高灵敏度达到56.93pm/(°),测量精度为0.02°。该传感器可通过改变等截面梁的宽度还可实现对倾角检测灵敏度的有效调节。