In this paper, a high-sensitivity fiber Bragg grating (FBG) tilt sensor using a cantilever-based structure is introduced. Two FBGs are fixed on a specially designed elastomer. One end of the elastomer is connected to the mass block, and the other end is connected to the shell. The principle of the tilt sensor is introduced in detail, and the mathematical model is established. The performance of the sensor is studied. The results show that there is a good linear relationship between the central wavelength difference of the two FBGs and the tilt angle in the range of -5° to 5°. The repeatability of the sensor is good, and the tilt sensitivity can reach 231.7 pm/°. The influence of the silicone oil on the damping capacity of the sensor is studied. The results show that the damping capacity of the sensor has been improved by sealing the silicone oil inside the shell of the sensor. The field test is carried out on a pier of an elevated bridge, and the result is good, which verifies the practicability of the sensor.

针对多芯光纤三维位型重构问题,提出了一种基于螺旋多芯光纤和Bishop标架的三维位形重构方法。分析了基于螺旋多芯光纤和Bishop标架的三维位形重构算法原理,实验采用了螺旋多芯光纤布拉格光栅(Fiber Bragg gating,FBG)阵列传感,通过光谱漂移计算各个纤芯的应变值,并根据节点截面应变关系模型实现了纤芯曲率和扭转角解算,最后,结合Bishop迭代计算得到光纤整体位形,实现了形状重构。进行了4种形状的重构实验,最大三维重构绝对误差为3.11mm。实验结果表明,基于Bishop-HMCF的形状重构方法能够实现三维位形重构,在柔性机构末端定位和导航上具有重要的研究意义与应用价值。

为了稳定准确地检测甲醇蒸汽浓度, 该文提出了一种基于聚甲基丙烯酸甲酯(PMMA)薄膜的光纤Bragg光栅(FBG)甲醇传感器。首先使用氢氟酸腐蚀部分包层, 在栅区表面涂覆一层PMMA薄膜;然后构建测量系统, 建立了传感器检测甲醇蒸汽的理论模型;最后引入温度补偿单元, 消除温度对甲醇蒸汽浓度测量产生的影响。实验研究了PMMA薄膜厚度和温湿度对传感器灵敏度的影响, 测试了传感器的响应时间、选择敏感性和检测下限。研究结果表明, 在甲醇质量浓度为20~160 mg/L时, 传感器的中心波长漂移与浓度间具有线性关系(线性系数R2=0.992)。在温度20~40 ℃, 相对湿度40%~80%时, 传感器能够准确检测甲醇蒸汽浓度的变化, 其灵敏度为0.292 pm/(mg·L-1), 相对误差为9.3%, 检测下限为20 mg/L。

FBG形状传感器的铺设角度偏差导致曲率和挠率测量误差，进而影响形状传感器的重构精度。针对该问题，文章提出了一种基于鲸鱼优化算法(Whale Optimization Algorithm，WOA)的FBG铺设角度偏差自矫正模型。重构实验验证了所提方法的有效性，不同形状的远端重构误差分别从11.66和22.6mm降低至5.63和10.47mm，相对误差分别从2.56%和4.96%降低至1.21%和2.25%，相对误差从2.56%和4.96%降低至0.95%和2.06%。

The strain-temperature cross-sensitivity problem easily occurs in the engineering strain monitoring of the self-sensing embedded with fiber Bragg grating (FBG) sensors. In this work, a theoretical investigation of the strain-temperature cross-sensitivity has been performed using the temperature reference grating method. To experimentally observe and theoretically verify the problem, the substrate materials, the preloading technique, and the FBG initial central wavelength were taken as main parameters. And a series of sensitivity coefficients calibration tests and temperature compensation tests have been designed and carried out. It was found that when the FBG sensors were embedded on different substrates, their coefficients of the temperature sensitivity were significantly changed. Besides, the larger the coefficients of thermal expansion (CTE) of substrates were, the higher the temperature sensitivity coefficients would be. On the other hand, the effect of the preloading technique and FBG initial wavelength was negligible on both the strain monitoring and temperature compensation. In the case of similar substrates, we did not observe any difference between temperature sensitivity coefficients of the temperature compensation FBG with one free end or two free ends. The curves of the force along with temperature were almost overlapped with minor differences (less than 1%) gained by FBG sensors and pressure sensors, which verified the accuracy of the temperature compensation method. We suggest that this work can provide efficient solutions to the strain-temperature cross-sensitivity for engineering strain monitoring with the self-sensing element embedded with FBG sensors.

The deformation and reconstruction of the composite propeller under the static load in the laboratory is studied so as to provide the basic research for the deformation and reconstruction of the underwater deformed propeller. The fiber Bragg grating (FBG) sensor is proposed to be used for strain monitoring and deformation reconstruction of the carbon fiber reinforced polymer (CFRP) propeller, and a reconstruction algorithm of structural curvature deformation of the CFRP propeller based on strain information is presented. The reconstruction algorithm is verified by using variable-thickness CFRP laminates in the finite element software. The results show that the relative error of the reconstruction algorithm is within 8%. Then, an experimental system of strain monitoring and deformation reconstruction for the CFRP propeller based on the FBG sensor network is built. The propeller blade is loaded in the form of the cantilever beam, and the blade deformation is reconstructed by the strain measured by the FBG sensor network. Compared with the blade deformation measured by three coordinate scanners, the reconstruction relative error is within 15%.

提出了一种基于对称悬臂梁的小型化低频光纤布拉格光栅(FBG)加速度传感器。首先根据传感器结构的力学模型, 推导出传感器的灵敏度和固有频率表达式; 然后对传感器进行结构参数优化, 采用ANSYS Workbench对传感器进行静应力与模态分析; 最后根据分析结果制作传感器, 并实验研究了传感器的幅频响应、灵敏度特性、横向抗干扰能力和冲击响应。结果表明, 该传感器固有频率为72Hz, 灵敏度为681.7pm/g, 抗横向干扰度小于4.9%, 且体积仅为6.48cm3, 可用于50Hz以下的低频微弱振动信号的实时监测。