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提出一种基于桥梁监测的光纤光栅振动传感器的设计方法。监测系统是基于测量压力啁啾的光纤布拉格光栅(FBG)反射带宽和反射光功率达到实时监控的目的。该传感器是由单根FBG组成,为了模拟真实桥梁振动情况,使用简支梁模拟桥梁。将单根FBG斜向粘贴在简支梁侧面上进行模拟试验,梁的上表面中间粘贴偏心轮来产生振动。振动将作用到简支梁上造成梁弯曲。梁弯曲时,在不同厚度层上产生呈梯度分布的应变,进而引起FBG的啁啾效应,造成FBG带宽发生变化。试验结果将电阻应变片和基于FBG的振动传感器进行对比。由于FBG对反射带宽和光功率温度不敏感,传感测量完全避开了温度的交叉敏感效应。该传感器可以广泛应用于桥梁的健康监测中,具有实时性及成本低等优点。
A design method of fiber grating vibration sensor based on bridge monitoring is proposed. The monitoring system is based on the real-time monitoring of the reflected bandwidth and the reflected optical power of a Fiber Bragg Grating (FBG) that measures the pressure chirp. The sensor is composed of a single FBG, in order to simulate the real bridge vibration, the use of simple beams simulate the bridge. A single FBG oblique paste on the side of the simple beam simulation test, the middle of the upper surface of the beam paste the eccentric to produce vibration. Vibration will act on the simple beam causing the beam to bend. When the beam is bent, a strain gradient distribution occurs in different thickness layers, which in turn causes the chirp effect of the FBG to change the bandwidth of the FBG. The test results compare the strain gage with an FBG-based vibration sensor. Because the FBG is insensitive to the reflection bandwidth and optical power temperature, the sensing measurement completely avoids the cross-sensitivity of temperature. The sensor can be widely used in the bridge health monitoring, with real-time and low cost advantages.