Strain Transfer Mechanism of Grating Ends Fiber Bragg Grating for Structural Health Monitoring

• 作者: Fangxiong Tang Guang Chen Keqin Ding Qibo Feng Xinran Yin
• 来源期刊: 结构耐久性与健康监测(英文)
• 学科: 工学
• 关键词: Structural health monitoring GRATING ENDS bonding fiber BRAGG GRATING the AVERAGE STRAIN transfer shear-lag theory
• 年，卷（期）: 2019,（3）
• 页码范围: 289-301
• 页数: 13页
• 分类号: TN2

摘要

The grating ends bonding fiber Bragg grating(FBG)sensor has been widely used in sensor packages such as substrate type and clamp type for health monitoring of large structures.However,owing to the shear deformation of the adhesive layer of FBG,the strain measured by FBG is often different from the strain of actual matrix,which causes strain measurement errors.This investigation aims at improving the measurement accuracy of strain for the grating ends surface-bonded FBG.To fulfill this objective,a strain transfer equation of the grating ends bonding FBG is derived,and a theoretical model of the average strain transfer from the matrix to the optical fiber is developed.Moreover,parameters that influence the average strain transfer rate from the matrix to the optical fiber are analyzed.A selection scheme of bonding parameters by numerical simulation is provided,which is significantly advantageous over that of the grating bonding FBG.The theoretical equation is verified by finite element method(FEM).Compared with the existing model,the proposed model has higher measurement accuracy.Experimental tests are performed to validate the effectiveness of the proposed model on the equalintensity cantilever beam,whose surface is attached to the bare FBG with grating ends bonding and strain gauge by using epoxy glue.The results show that there is a great agreement between the outcome of the bare FBG and that of the strain gauge,and the corrected strain is closer to the true strain.The proposed model provides a theoretical basis for the design of the grating ends surface-bonded FBG strain sensor for health monitoring of large structures.