带宽调制型单光纤光栅温变无补偿位移传感

报道了利用反射谱带宽调制和光强差分探测技术实现单一光纤光栅温变无补偿位移精确测量的新方法。设计了一种结构新颖的曲臂梁位移传感装置,结合光波导理论与材料力学原理分析了光纤光栅在高斯应变作用下光栅反射谱侧向梯度展宽的成因,理论推导了特殊结构梁在外力作用下光栅反射谱带宽/反射光强与压力之间的响应关系。光栅反射谱侧向梯度展宽的同时反射光强线性增加,利用光强差分检测方法消除光源出光抖动的影响,提高了位移测量精度。基于带宽调制的光纤光栅位移传感方法免受温度变化的影响,在-10℃~80℃的温度变化范围内,测量误差小于1.2%,实现了单光纤光栅温变无补偿位移测量。     

光纤光栅称重传感器研究

提出一种基于光纤光栅传感技术的称重系统.用特种粘贴剂将布喇格光纤光栅(FBG)粘贴于悬臂梁的自由端,当悬臂梁自由端受力发生微挠度弯曲时,光纤光栅将沿轴向发生形变,通过监测布喇格光纤光栅传感器反射波长漂移测量悬臂梁的微挠度变化.通过分析悬臂梁结构,建立悬臂梁受力与挠度的数学关系,进而测量出加载在悬臂梁自由端应力的数值.通过对系统结构理论分析和实验验证,该装置称重测量范围达到50千克力,测量灵敏度达到0.05千克力,线性拟合度达到0.9997.     

Temperature-insensitive fiber Bragg grating dynamic pressure sensing system

Temperature-insensitive dynamic pressure measurement using a single fiber Bragg grating (FBG) based on reflection spectrum bandwidth modulation and optical power detection is proposed. A specifically designed double-hole cantilever beam is used to provide a pressure-induced axial strain gradient along the sensing FBG and is also used to modulate the reflection bandwidth of the grating. The bandwidth modulation is immune to spatially uniform temperature effects, and the pressure can be unambiguously determined by measuring the reflected optical power, avoiding the complex wavelength interrogation system. The system acquisition time is up to 85 Hz for dynamic pressure measurement, and the thermal fluctuation is kept less than 1.2% full-scale for a temperature range of -10 degrees C to 80 degrees C.     

Dynamic analysis and temperature measurements of concrete cantilever beam using fibre Bragg gratings

We analyzed the action of fire, causing degradation in a concrete cantilever beam using dynamic testing. The structure was fitted with two fibre Bragg gratings (FBG) sensors. One of them measured vibration and the other measured the temperature inside of the cantilever beam, while the beam was exposed to fire. A high-temperature probe based on a simple packaging system, which isolates the sensing FBG from any mechanical action, was developed. A low-cost fibre Bragg grating interrogation system, including easy assembly and maintenance, was used for the measurements. The temperature in the cantilever beam increased until 150 °C and a reduction in the strength of concrete was observed through modal analysis. Results reveal a considerable reduction in strength occurs even with exposures to moderate temperatures (less than 90 °C).     

光纤光栅弹簧管压力传感器的压力和温度特性

本文利用弹簧管对于压力的机械放大作用,将弹簧管与光纤光栅悬臂梁调谐技术相结合,研制了一种新颖的光纤光栅弹簧管压力传感器,大大提高了光纤布喇格光栅对压力测量的灵敏度,压力灵敏度系数可达-1.79×10^-4/MPa,比裸光栅提高了两个数量级,在0～12MPa的压力范围内,光纤布喇格光栅中心反射波长的改变与压力成良好的线性关系.同时由于悬臂梁热膨胀效应的影响,光纤光栅的温度灵敏度提高为裸光栅的7倍.     

单光纤光栅波谱展宽温度压力同时区分测量

报道了利用单光纤布拉格光栅反射波带宽展宽技术实现温度与压力同时区分测量的新方案。通过聚合物材料将光栅粘接于双孔悬臂梁非均匀应变区 ,在压力作用下悬臂梁带动光栅发生非均匀应变 ,使布拉格反射波波长漂移的同时带宽展宽 ,而温度变化仅引起反射波波长漂移。在 2 0～ 10 0℃和 0～ 7.8N的温度和压力测量范围内 ,温度测量精度± 1.1℃ ,压力测量精度± 0 .18N ,布拉格反射波中心波长漂移量和带宽展宽量随温度和压力的变化呈良好的线性关系 ,线性度均高于 99.6 %。多次测量表明 ,此方案的展宽波形稳定 ,重复性好。     

光强检测型光纤光栅温变不敏感动态压力传感研究

报道了基于光纤光栅反射谱带宽调制和光强差分检测技术实现单一光纤光栅温变不敏感动态压力传感的新方法。设计了一种结构新颖的双孔梁压力传感装置,依据双孔梁有限元受力分析将光纤光栅准确定位于线性梯度应变区,压力作用下光纤光栅反射谱对称展宽,反射光强线性正比于压力变化。基于光波导理论和材料力学原理推导了线性梯度应变场作用下光栅反射谱带宽、反射光强与压力之间的响应关系。利用光强差分检测技术取代传统波长解调方法,简化解调过程的同时传感系统免受温变影响。实验表明,在-10~80℃的温度变化范围内,系统测量误差小于总量程(120kPa)的1.8%,动态响应速度约80Hz,重复测量系统输出稳定,具有较好的应用价值。     

新型高准确度光纤光栅压力传感系统

提出一种使用光纤双布喇格光栅测定压力的测量方法.在外界压力作用下,传感光纤布喇格光栅反射波长的漂移,被转变成在交变力策动下,发生弯曲的等强度悬臂梁调制扫描光栅反射光脉冲间隔的变化.实验结果表明,光纤布喇格光栅反射波长漂移的测量范围为0～3 nm,波长测量的不确定度为1 pm;压力传感器的量程为0～6 MPa时,压力的测量不确定度为0.005 Mpa.     

新型光纤布拉格光栅温度自动补偿传感研究

将光纤布拉格光栅斜向粘贴于厚度相等的等腰三角形悬臂梁的侧面，利用光纤光栅啁啾效应，通过测量带宽进行多种力学量的传感研究。理论和实验均证明，该传感装置具有温度自动补偿功能。在位移、应力等参量的传感实验中获得了很好的线性响应，位移和应力传感的灵敏度分别为2.47nm/mm和2.26nm/N，光纤光栅实验带宽达15.5nm。     

基于啁啾光纤光栅的温度自补偿位移传感器

基于双三角结构的悬臂梁,提出了一种使用啁啾光纤光栅测定位移的方法.悬臂梁受到应力时引起刚性粘接在悬臂梁上的啁啾光栅反射谱带宽压缩,通过测量反射谱带宽进行位移的测量.该结构克服了位移测量时温度的交叉敏感问题,温度变化引起反射谱整体移动但不会改变带宽.测试结果表明该传感器具有较高精度、良好的线性和可重复性等优点.     

Proposal of metal bellows-based fiber Bragg grating accelerometer

A metal bellows-based fiber Bragg grating(FBG) accelerometer is proposed and experimentally demonstrated. The optical fiber(containing the FBG) is pre-tensioned,and the two ends of the optical fiber are fixed directly from the shell to the inertial mass. In this design,the FBG is uniformly tensioned to obtain a constant strain distribution over it. By employing this configuration,the FBG always has a sharp reflection characteristic with no broadening in its reflection spectrum during wavelength shifting. Dy...     

基于光纤光栅的一体式靶式流量传感技术

针对以往液压系统检测中存在的特点,如结构杂、体积大、精度低,设计了一种基于光纤布拉格光栅(FBG)的一体式靶式流量传感器。分析了FBG及靶式流量传感原理,设计出一种组成紧凑、便于密封以及拆装的一体式靶片,将放在流体里的靶片受到的与流速成相关变化的冲击力变为FBG波长的漂移,双FBG对称分布,分别放在悬臂梁两表面中轴线处,这种差动形式可以很好地增加灵敏度,并且可以解决应变和温度的交叉敏感现象。通过FLUENT分析了流体形式,结果显示这种结构给流体造成的影响比一般结构小。实验测试过程中,双FBG中心波长总变化数值和放置于靶片的质量呈现出明显的线性变化,并且灵敏度为一个FBG灵敏度的双倍,可靠性以及稳定性较好。     

双悬臂梁光纤Bragg光栅应力传感器

报道了一种新颖的光纤Bragg光栅应力传感器.理论分析和实验证明了这种传感器Brrag光栅中心波长随应力变化的线性工作区.将光纤Bragg光栅贴于双悬梁的梁端面,在双悬梁的自由端部施加载荷,对光纤Bragg光栅的应力响应特性测试.当所加载荷为300 g时,光纤Bragg光栅中心波长变化了0.156 nm.从实验上获得了－0.05 nm/N的应力响应灵敏度.该结构具有应力增敏作用,且应力响应的线性、重复性和迟滞性较好.应力响应灵敏度随着梁的大小以及材料的力学参量的改变而改变.     

平面圆形膜片式光纤布拉格光栅温度补偿压强传感

报道了利用光纤布拉格光栅反射波谱带宽展宽技术实现温度补偿的压强传感新方案。结合平面圆形膜片应变调谐的特点,采用膜盒式结构,将光纤光栅中心对准平面圆形膜片零应变半径并沿径向粘贴,利用反射波谱带宽对应变敏感而对温度不敏感的特性解调压强,成功地实现了温度补偿的压强传感测量。基于光谱分析仪0.05nm的光谱分辨力,实验测得带宽随压强响应灵敏度为0.34nm/MPa,压强精度为±0.15MPa,压强测量范围为0~7.5MPa。实验结果与理论分析基本一致。     

Flextensional fiber Bragg grating-based accelerometer for low frequency vibration measurement

The intelligent structural health monitoring method,which uses a fiber Bragg grating(FBG) sensor,is a new approach in the field of civil engineering. However,it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements. In this letter,a flextensional FBG-based accelerometer is proposed and demonstrated. The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz,with a high sensitivity of 410.7 pm/g. In addition,it has a br...     

基于平面膜片的光纤光栅传感研究

提出了一种基于平面膜片的光纤光栅压强传感器.讨论了该传感器反射谱展宽、峰值波长变化与压强之间的关系.指出将光纤光栅沿径向粘贴在膜片中心附近时,反射谱的峰值波长与压强之间具有良好的线性关系,可以通过检测峰值波长来检测压强.该传感器的压强响应灵敏度系数的实验值为0.3964 nm/MPa,是裸光纤光栅压强灵敏度系数的132.1倍.该传感器的灵敏度系数与压强测量范围可以通过改变膜片的尺寸、材料的弹性模量、泊松比等参量来调节.     

Wavelength-spacing-tunable multichannel filter incorporating a sampled chirped fiber Bragg grating based on a symmetrical chirp-tuning technique without center wavelength shift

We propose and experimentally demonstrate a simple and flexible scheme for a wavelength-spacing-tunable multichannel filter exploiting a sampled chirped fiber Bragg grating based on a symmetrical modification of the chirp ratio. Symmetrical bending along a sampled chirped fiber Bragg grating attached to a flexible cantilever beam induces a variation of the chirp ratio and a reflection chirp bandwidth of the grating without a center wavelength shift. Accordingly, the wavelength spacing of a sampled chirped fiber Bragg grating is continuously controlled by the reflection chirp bandwidth variation of the grating corresponding to the bending direction, which allows for realization of an effective wavelength-spacing-tunable multichannel filter. Based on the proposed technique, we achieve the continuous tunability of the wavelength spacing in a range from 1.51 to 6.11 nm, depending on the bending direction of the cantilever beam.     

用光纤光栅传感器测量外压力的动态调制方法

为了提高光纤布拉格光栅压力传感器的精度和降低系统成本，提出一种使用光纤双布拉格光栅测定压力的测量方法，即在外界压力作用下，传感光纤布拉格光栅反射波长的飘移被转变成在交变力策动下发生弯曲的等强度悬臂梁调制的扫描光栅的反射光脉冲间隔的变化。实验结果表明：光纤布拉格光栅反射波长漂移的测量范围为0～3nm，波长测量的不确定度为1pm；压力传感器的量程为0～6MPa时，压力的测量不确定度为0.005MPa。     

基于光纤Bragg光栅反射波带宽展宽的压力传感研究

报道了一种新颖的光纤Bragg光栅压力传感装置,提出并实现了利用光纤Bragg光栅反射波带宽展宽实现压力传感的新方法.利用压力作用下双孔悬臂梁非均匀应变带动光栅使Bragg反射波漂移的同时带宽展宽,实现压力传感.在0~23.5 N的测量范围内,基于光谱分析仪0.05 nm的光谱分辨率,压力分辨率为0.54 N,带宽最大展宽量2.14 nm,压力响应曲线具有良好的线性.多次测量表明：展宽波型稳定,重复性好.     

Simultaneous measurement of bending and temperature based on a single sampled chirped fiber Bragg grating embedded on a flexible cantilever beam

We propose and experimentally demonstrate a simple and practical scheme for simultaneous measurement of bending and temperature based on a single sampled chirped fiber Bragg grating with multiple resonant peaks, which is embedded on a flexible cantilever beam. The wavelength spacing of the grating can be changed by adjusting the bending curvature change, since the compressive strain gradient induced by the bending of the cantilever beam changes the chirp ratio of the fiber grating. However, the wavelength spacing of the fiber grating is not changed by the temperature variation; the multiple resonant wavelengths are only shifted into the longer wavelength because of the positive thermal-expansion and thermo-optic coefficients of the fiber grating. Consequently, the proposed scheme allows for discrimination between two effects of bending and temperature.