Interface strain transfer mechanism and error modification for adhered FBG strain sensor

The application of adhered FBG strain sensor is affected by interface strain transfer and error modification. In his paper, firstly, based on the characteristics of forces and damage, the fundamental hypotheses are given, and the general expression of interface transferring mechanism is derived. After that, united form of the characteristic value-λ for the general equation is given for the multi-layer coatings. Finally, according to the error-modified equation of adhered FBG sensor, the relationships the error rate η against the shear modulus and the thickness of the glue are given. With regard to the glue applied in engineering (thickness is from 4mm to 60mm, shear modulus is from 30MPa to 200MPa), the error rate η is about 5-10%, and the correction coefficient k is about 1.05-1.11. Hence, the error modification must be considered when adhered FBG strain sensors are used in civil engineering.