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在布拉格光栅(FBG)光纤的包层中制作微槽,结合敏感材料提高了FBG光纤传感器的灵敏度,拓宽了其传感应用领域。利用飞秒(fs)激光对I型布拉格光栅光纤进行刻蚀,通过调节激光功率和辐照时间,分析光纤折射率变化以及光纤表面和内部结构的刻蚀特性,并探讨fs激光对光纤光栅微沟槽形貌和反射光谱的影响。实验结果表明,微槽表面由于碎屑的凝固而产生许多柱状结构,且随着激光能量的增加,柱状结构不断长大,槽深和形状服从高斯能量分布;随着激光功率和辐照时间的增加,反射率谱永久红移,带宽增加。利用微结构光纤增敏性能,有效提高微结构光纤光栅磁场探头和氢气探头的传感性能。 相似文献
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本文提出了一种基于光纤布拉格光栅(FBG)温度解耦方法的光纤法珀(FP)压力传感器,该传感器采用低温共烧陶瓷(LTCC)技术实现批量化制作.通过在膜片式压力传感器的基础上集成光纤布拉格光栅(FBG),实现温度、压力双参数测量;提出温度解耦方法,对传感器进行温度补偿及压力测量结果的修正.实验结果表明,在20~300℃的温度范围内, FBG温度传感器的灵敏度为0.012 nm/℃,在160 kPa的压力范围内,压力测量灵敏度约为0.1μm/kPa, 3次重复实验的重复性误差和非线性误差分别约为5.6%和1.3%,温度系数为0.018μm/℃,压力灵敏度随温度变化为0.283 nm/(kPa·℃),同时,采用温度解耦方法,得到压力计算值与真实值最大偏差小于2.5 kPa. 相似文献
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介绍了光纤布拉格光栅传感器测温的基本原理以及一些布拉格光纤的封装方法,在此基础之上探讨了一种新型的布拉格光纤光栅的封装方法即用钢条对布拉格光纤光栅进行封装,并通过实验对祼光栅和封装后光栅的温度特性进行了研究.实验采用了恒温水浴装置,在25℃至70℃温度范围使用了中心波长为1530.5 nm的光纤布拉格光栅进行测量.先进行了祼光栅的测量,在光栅封装之后又进行了测量.实验结果表明,光纤光栅在封装之后温度灵敏度为裸光栅的2.5倍.其线性拟合度达到0.996. 相似文献
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从光纤布拉格光栅温度传感模型出发,对光纤布拉格光栅温度传感的理论进行了分析,并通过实验对裸光栅的温度特性进行了研究,推导出了光纤布拉格光栅温度传感的一阶有效线性灵敏度系数的解析式.实验结果表明,光纤光栅在所测温度范围内具有良好的线性特性,与理论结果基本一致.表明光纤光栅温度传感的理论模型具有良好的实验基础. 相似文献
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采用在平板表面开槽并铺设具有布拉格光栅的裸光纤来测量平板的表面压力,利用平板表面弯曲路径的凹槽,使裸光纤各测量点能实现独立测量;研究了粘贴剂弹性模量和凹槽尺寸对压力灵敏度的影响,利用有限元仿真验证了光纤平均轴向应变和平均压力值之间的良好的线性关系,得出可以利用光纤平均轴向应变来对平板上多点的平均压力进行测量的结论。 相似文献
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将布拉格光纤光栅(FBG)埋植于复合材料T型加筋板结构非干涉区—三角填充区作为应变传感器对复合材料加筋板在固化过程及冲击后压缩过程中的应变变化进行监测。对比了光纤刻栅区采用UV光固化树脂涂层保护和未保护的两种FBG传感器的波谱信号变化; 分析了复合材料在固化成型过程中产生的非轴对称热残余应力对FBG传感性能的影响。结果表明, 刻栅区采用聚合物涂层保护的FBG传感器的半峰宽(FWHM)在固化过程中未发生变化, 并且聚合物涂层可以有效地消除非轴对称热残余应力对光纤光栅反射波谱的影响。在冲击后压缩过程中, 采用聚合物涂层保护的FBG传感器测得的应变与贴于试样表面的应变片测得的应变数据一致性较好。本文对埋植于复合材料加筋板三角填充区的FBG传感器在复合材料固化过程及冲击后压缩过程中应变监测的有效性及可靠性进行了有益的探索。 相似文献
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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. 相似文献
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针对碳纤维增强树脂复合材料低速冲击损伤的实时监测,设计将布拉格光纤光栅(FBG)传感器埋植在复合材料T型加筋板结构的三角填充区,在线监测复合材料T型加筋板冲击损伤过程。分别将FBG传感器埋植于复合材料层合板内部和复合材料T型加筋板的三角填充区,对比FBG传感器的埋入对复合材料层合板和复合材料T型加筋板力学性能的影响。结果表明,内埋FBG传感器的复合材料层合板试样的拉伸强度比未埋植传感器的层合板试样降低了约5%,但在FBG传感器的破坏应变范围内,FBG传感器可以准确、实时地监测复合材料的应变信号。将FBG传感器埋入复合材料T型加筋板的三角填充区,内埋FBG传感器的T型加筋板样件压缩破坏载荷与未埋植的样件基本一致。通过对比T型加筋板蒙皮上冲击位置、冲击能量对FBG传感器测得的冲击过程持续时间和最大应变值的影响,表明冲击过程持续时间随着冲击能量增大而延长,最大应变值随着冲击距离的增加呈下降趋势,而最大应变值随着冲击能量的增大呈上升趋势。利用FBG传感器测得的应变信号可初步实现对复合材料T型加筋板蒙皮冲击损伤位置及冲击能量的实时监测。 相似文献
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Theoretical Analysis on Strain Transfer Error of FBG Sensors Attached on Steel Structures Subjected to Fatigue Load
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Fibre Bragg grating (FBG) sensors have been increasingly adopted to detect the dynamic strain of structures. When the sensor is attached on the surface, adhesive material is employed to assist the installation, which leads to indirect contact of sensing fibre and the monitored structure. To correct the strain transfer error induced by the shear lag effect and improve the measurement accuracy of FBG sensors under dynamic response, strain transfer mechanism of a three‐layered testing model constituted of sensing fibre, adhesive layer and host material has been studied in this paper. Laboratory test on steel beam attached with FBG sensor under fatigue load has been projected to investigate the feasibility of the derived strain transfer formula, and numerical simulation by MATLAB has been used as a supporting tool to offer the reference dynamic strain. Based on the analysis, sensitive parameters that affect the strain transfer coefficient have been discussed to instruct the application design of FBG sensors. Results indicate that strain transfer coefficient under dynamic response is much lower than that in static state, and error modification is particularly significant; in the dynamic testing model, bonded length, shear modulus and thickness of adhesive layer are more sensitive, which should be precisely selected in practical engineering to guarantee the effective strain measurement. 相似文献
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本文对应用光纤Bragg光栅传感器编入三维编织复合材料结构内部的测量进行了研究.首先简要介绍了光纤光栅的编入方法和传感原理.随后进行的实验结果显示由应变计及光纤光栅所得到的载荷-应变曲线都具有良好的线性关系,实验之间的结果符合得很好,表明光纤Bragg光栅传感器可以用来精确检测编织试件复杂载荷状态下的内应变.从而将会促进光纤光栅在3-D编织复合材料结构的内部结构检测和强度失效分析中的更广泛应用. 相似文献
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《Composites Part B》2001,32(1):33-45
In this paper, the mechanical behaviour of the composite-strengthened concrete structures is addressed. Optical fibre sensor presents a great deal of potential in monitoring the structural health condition of civil infrastructure elements after strengthening by externally bonded composite materials. The use of embedded optical fibre sensor for strain and temperature monitoring enables to reveal the status of the composite-strengthened structure in real-time remotely. In this paper, an experimental investigation on the composite-strengthened concrete structures with the embedment of fibre-optic Bragg grating (FBG) sensors is presented. Single- and multiplexed-point strain measuring techniques were used to measure strains of the structures. Frequency modulated continuous wave (FMCW) method was used to measure strains in different points of the structure with using only one single optical fibre. All strains measured from the sensors were compared to conventional surface mounted strain gauges. Experimental results show that the use of the embedded FBG sensor can measure strain accurately and provide information to the operator that the structure is subjected to debond or micro-crack failure. Multiplexed FBG strain sensors enable to measure strain in different locations by occupying only one tiny optical fibre. Reduction of strength in composite laminate is resulted if the embedded optical fibre is aligned perpendicular to the load-bearing direction of the structure. 相似文献
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In this work a new superstructured, in-fiber Bragg grating (FBG)-based, contact force sensor is presented that is based on birefringent D-shape optical fiber. The sensor superstructure comprises a polyimide sheath, a stress-concentrating feature, and an alignment feature that repeatably orients the sensor with respect to contact forces. A combination of plane elasticity and strain-optic models is used to predict sensor performance in terms of sensitivity to contact force and axial strain. Model predictions are validated through experimental calibration and indicate contact force, axial strain, and temperature sensitivities of 169.6 pm/(N/mm), 0.01 pm/με, and -1.12 pm/°C in terms of spectral separation. The sensor addresses challenges associated with contact force sensors that are based on FBGs in birefringent fiber, FBGs in conventional optical fiber, and tilted FBGs. Relative to other birefringent fiber sensors, the sensor has contact force sensitivity comparable to the highest sensitivity of commercially available birefringent fibers and, unlike other birefringent fiber sensors, is self-aligning with respect to contact forces. Unlike sensors based on Bragg gratings in conventional fiber and tilted Bragg gratings, the sensor has minimal cosensitivity to both axial strain and changes in temperature. 相似文献
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《Composites Science and Technology》2003,63(13):1885-1894
Small-diameter FBG sensors were applied for the detection of edge delamination in carbon fiber reinforced plastic (CFRP) quasi-isotropic laminates. Reflection spectra from the embedded fiber Bragg grating (FBG) sensor were measured at various lengths of delamination initiated from the edge of the specimen under cyclic loading. The form of the spectrum changed sensitively as the edge delamination grew. For confirmation of the measured results, the strain distribution in the FBG sensor was calculated by FEM analysis and the spectrum was simulated from the strain distribution theoretically. The change in the form of the measured spectrum was consistent with that of the calculated spectrum. From these results, the spectrum was found to depend on the size and location of the edge delamination. Moreover, the intensity ratio of the two peaks in the spectrum was proposed as an effective indicator for the quantitative evaluation of the edge delamination size. 相似文献
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An intracore Bragg grating written on a photosensitive fiber core is used for strain measurement in composite specimens under load. The strain information is directly related to the absolute change in the Bragg-reflected wavelength. Fiber Bragg grating (FBG) sensors (fibers with intracore gratings) are thus sensitive to strain that is caused by changes in temperature as well as to load-induced changes. Thus these sensors can be made to be independent of source intensity variations and losses. FBG sensors used for load-induced strain sensing in composite structures and the effects of temperature on them are discussed. A detailed account of the use of such embedded structures as self-monitoring nondestructive testing devices is given. 相似文献