正向压力下FBG柔性传感器界面滑移的应变误差分析

Analysis of Strain Error of FBG Flexible Sensor with Relative Slip under Vertical Pressure

为了研究光纤布拉格光栅柔性传感器与封装材料界面间的相对滑移引致的应变误差是否可以忽略,采用ANSYS有限件元仿真软,分析了滑移引起的纤芯各点轴向应变的相对误差与正向压力关系,通过分析影响传感器结构的敏感性参数包括纤芯材料、涂覆层材料、封装材料与尺寸,探讨相对滑移对光纤布拉格光栅轴向应变相对误差的影响.研究结果表明,正向压力在[0.1 N,10 N]范围时,纤芯各点轴向应变相对误差随着正向压力的增大而减小,且呈现纤芯小两端大的趋势.实际应用中应结合正向压力大小,选取弹性模量较小的纤芯材料和摩擦系数较大的封装材料,可使轴向应变相对误差小于10%;选择涂覆层弹性模量为2.4×10^10 Pa,厚度为0.0625 mm,可使轴向应变相对误差降低到8.57%;当光纤布拉格光栅半埋入长度大于40 mm时,纤芯的轴向应变相对误差总体低于20%,此时可认为涂覆层与硅胶之间为完全粘结,无相对滑移.

To discuss the strain error caused by the relative slip between the flexible Fiber Bragg Grating sensor and the substrate material,ANSYS finite element simulation software was used to analyze the relationship between the relative error of axial strain at each point of the core and the forward pressure.The parameters affecting strain transfer of the sensor,including core material,coating material,substrate material and size were analyzed,and the effect of relative slip on the relative error of FBG axial strain were explored.The results show that the relative error of axial strain at each point decreases with the increase of forward pressure,when the pressure is in the range of[0.1 N,10 N],which presents the trend of small in core and big in two ends.In practical application,it should be combine the positive pressure to select the core material with less elastic modulus and the substrate material with higher friction coefficient,the relative error of axial strain could be less than 10%;select coating elastic modulus 2.4×10^10 Pa,0.0625 mm thickness,the relative error of axial strain could be reduced to 8.57%;when half length of the FGB is more than 40 mm,the axial strain relative error of the core could be less than 20%,at this point,it could be considered that the coating and silica gel are completely bonded.