胶黏剂黏弹性对粘贴式FBG应变传递的影响

考虑到FBG传感器用于机床应变监测时,胶黏剂蠕变对静态载荷下FBG应变传递的影响,研究了胶黏剂线黏弹性对粘贴式FBG应变传递的影响规律。基于粘贴层为线黏弹性材料重新建立了粘贴式FBG应变传递模型,并将粘贴层简化为三参量固体模型,得到了粘贴式FBG传感器瞬时和准静态的应变传递关系。然后,通过理论和实验分析了粘贴长度、宽度、高度和中间层厚度对瞬时和准静态应变传递的影响。实验结果表明:在恒定应力作用下,黏接剂蠕变会导致FBG的应变随时间而变化,当粘贴长度在30mm以上时,FBG应变传递率随时间的变化在4%左右;当粘贴长度为15mm时,应变传递率变化接近7%。分析该结果得出:适当增加粘贴长度,减小粘贴中间层厚度可以减小胶黏剂蠕变对应变传递的影响。该结论对基于粘贴式FBG的高精密测量具有指导意义。

Effect of adhesive viscoelasticity on strain transfer mechanism of bonded FBG

The effect law of adhesive visco-elasticity on bonded FBG strain transfer was studied in consideration of the effect of adhesive creep on FBG strain transfer under static load during the application of FBG sensor to machine tool strain monitoring. The bonded FBG strain transfer model was re-established for the linear visco-elastic material based on the bonding layer which is simplified as a three-parameter solid model, thus the instant and quasi-static strain transfer relation of the bonded FBG sensor was obtained. Then, the effects of the bonding length, width and height and thickness of interlayer on the instant and quasi-static strain transfer were analyzed through theory and experiment. The experimental results show that: the adhesive creep will lead to the variation of FBG strain with time under the constant stress action; when the bonding length is above 30 mm, the FBG strain transfer ratio change with time is about 4%; when the bonding length is 15 mm, the strain transfer ratio change is approximate 7%. The analysis implies that the appropriate increase of bonding length and decrease of the thickness of bonding interlayer can reduce the effect of adhesive creep on strain transfer. This conclusion has guiding significance for the high-precision measurement based on bonded FBG.