动态应力场作用下线性啁啾光栅光谱特性研究

目前柔性结构损伤检测需多个传感器，且需要探测器具有极高的采集频率。光纤光栅具有动态响应快、易实现分布式测量等特点，为解决上述问题提供了有效的途径，提出采用线性啁啾光栅(LCFBG)实现动态应力场探测。首先，用传输矩阵理论建立了LCFBG反射光谱应变传感模型，用衰减正弦函数模拟沿LCFBG分布的动态应力场。通过仿真实验，详细研究了LCFBG反射光谱对不同振幅、不同衰减系数与不同传播速度动态应力场的响应特性。实验结果表明，LCFBG反射光谱的反射率、波长变化与光谱形状均与动态应力场上述参数有关，但是LCFBG反射光谱对动态应力场不同参数的响应规律不同。在一定范围内，LCFBG反射光谱的最大反射率随动态应力场幅值与速度的增大而增大，最终趋于一稳定值，但其随阻尼系数增大而减小。最后，研制了以LCFBG为敏感元件的传感器，并构建了动态应力场实验平台，实验结果与仿真实验数据基本一致。提供了一种通过实时采集LCFBG全光谱信息探测动态应力场的新方法。

Research on the Reflection Spectrum of Linear Chirped Fiber Bragg Grating under the Impact of Dynamic Stress

Dynastic stress field detection based on the linear chirped fiber Bragg grating (LCFBG) was proposed. Firstly, the reflectance spectra strain sensing model of LCFBG adopting the transfer matrix method was constructed, and attenuation sine function was used to simulate the dynamic stress field along LCFBG. In the simulation experiment, the responding character of LCFBG reflection spectrum to different amplitude, different attenuation coefficient and different propagation speed of dynamic stress was studied in detail. The simulation results show that the reflectivity, wavelength and spectral shape of LCFBG reflection spectrum are related to the dynamic stress. However, the LCFBG reflection spectrum has different response to different parameters of dynamic stress. In a range, maximum reflectivity of LCFBG reflectance spectra increases when the amplitude and propagation speed of dynastic stress field becomes larger, but it decreases when the attenuation coefficient increases. Eventually, vibration sensor using LCFBG as the sensing element was designed, and then LCFBG dynamic stress fluctuations experiment platform was build. The data obtained from experiment agrees with the simulation results. Therefore, a novel detection method of dynamic stress field through real-time acquisition of LCFBG full spectral information is proposed in this article.