非轴向力下粘贴式FBG传感器应变传递机制研究

摘要

研究了结构监测中粘贴式光纤布拉格光栅(FBG)传感器轴线方向与基体结构主应力方向成一定角度时,传感器测量的应交与基体结构实际应变的关系.建立了非轴向力作用下粘贴式FBG传感器应变传递方程和应变传递理论模型,并得到沿传感器标距各点的应变传递率、最大应变传递率和平均应变传递率.通过有限元仿真验证了理论模型的有效性,通过参数分析得到平均应变传递率随传感器角度变化的规律.研究结果表明:平均应变传递率随传感器角度的增大而减小,当传感器角度为零时,平均应变传递率最大,且方程形式与轴向力情况相同,因此推导所得的方程可归结为平均应变传递率的一般表达式；当传感器角度为90°时,平均应变传递率为零,此时传感器不能测出基体结构的应变.给出的理论模型及仿真结果对指导粘贴式FBG传感器在结构健康监测中的实际应用有参考价值.%The relationship in structural health monitoring between the strain measured by a surface-bonded fiber Bragg grating (FBG) sensor and the actual strain of the matrix structure when the direction of the sensor axis is at a certain angle to the main stress direction of the matrix structure was investigated.The strain transfer equation and the theoretical strain-transfer model of a surface-bonded FBG sensor were established,and the strain transfer rate along the sensor gauge,the maximum strain transfer rate and the average strain transfer rate were obtained.The validation of the theoretical model was verified by the finite element method (FEM),and the change of the average strain transfer rate with the sensor angle was obtained by the parameter analysis.The results of the study show that the average strain transfer rate decreases with the increase of the sensor angle.When the sensor angle is zero,the average strain transfer rate is the largest,and its equation form is the same as the axial force case.Therefore,the theoretical model could be attributed to the general expression.When the sensor angle is 90°(the direction of the sensor axis is vertical to the principal stress direction of the matrix structure),the average strain transfer rate drops to zero.In this case,the measurement result is invalid.The theoretical model and simulation results are of referential significance to guiding the practical application of the surface-bonded FBG sensor in structural health monitoring.