基于桥梁健康监测的振动传感器

FIBER BRAGG GRATING VIBRATION SENSOR USED FOR BRIDGE HEALTH MONITORING

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。

An intensity-modulated,fiber Bragg grating( FBG) vibration sensor using on bridge health monitoring is proposed and experimentally demonstrated. The sensing mechanism is based on the measurement of optical power of a strain-chirped FBG. An initially-uniform FBG is glued with a slanted direction onto the lateral surface of a simplysupported beam to simulate bridge. An eccentric gear is installed in the middle of the beam,which can transfer the vertical vibration to the deflected beam. Therefore,deflection-induced nonuniform strain is applied to the sensing FBG and makes it chirped. The experimental results are compared with the measurement results of a resistance strain sensor,and good agreement is achieved. Furthermore,this sensor is cost-effective and inherently insensitive to temperature. The sensor can be widely used in bridge health monitoring,with real-time and low cost.