The optical fibre sensing technology has been widely used to measure the internal strain of similar material. However

the coupling between the optical fibre and similar materials has not yet been resolved. In previous studies

theoretical results of strain transfer cannot be validated in the experiments. A one-dimensional optical fibre Bragg grating (FBG) similar material was designed and realized using three layers of fibre-adhesive-similar material. The sensor provides a method to solve the problem of coupling between the fibre and similar material. The FGB sensor without coating layer was used as the sensing element

and the axial centre strain was measured by using the fibre embedded in the similar-material strain testing pieces. We investigated the behaviour of strain transfer using theoretical analysis

numerical simulation and a newly designed calibration. The results of the average strain transfer rate of the sensor obtained by different methods were very close

which demonstrated good coupling among fibre

adhesive and similar material. Moreover

the accuracy and reliability of theoretical analysis and numerical simulation were verified by a new calibration experiment. The method provides a feasible solution for the three-dimensional strain measurement of similar material in the model.