Due to the distinctive merits of FBG, e.g., compact size and immune to electromagnetic, strain sensors based on FBG
have attracted an increasing number of attentions in the field of structural health monitoring. But it is not easy to
fabricate a strain sensor which can survive at high temperature, because normal material can not stand in a strain creep
when the temperature is higher than 200°C. In this paper, a novel strain sensor consisting of a high temperature resistant
FBG and a metal rhombus structure is presented and demonstrated for surface strain measurement. The FBG is bonded
on the metal structure via a low softening point glass and pre-stretched about 2nm before it is bonded, so it can measure
compress and stretch tension. The experimental result shows that the proposed strain sensor can survive at 300°C, and
the average wavelength-strain sensitivity for compress and stretch, are 1.821 pm/μepsilon and 1.814 pm/μepsilon , respectively.
A more insensitive material to temperature and more appropriate adhesive are needed to improve the linear relationship
in the next step.
Fiber Bragg Grating (FBG) sensing technology has many applications, and it’s widely used in detection of temperature, strain and etc. Now the application of FBG sensor is limited to the temperature below 200°C owing to the so called High Temperature Erasing Phenomenon. Strain detection over 200°C is still an engineering challenge since high temperature has a bad influence on the sensor, testing equipment and test data, etc, thus effective measurement apparatus are needed to ensure the accuracy of the measurement over 200°C, but there are no suitable FBG strain experimental apparatus in high temperature to date. In this paper a high temperature FBG strain experimental apparatus has been designed to detect the strain in high temperature. In order to verify working condition of the high temperature FBG strain, an application of FBG strain sensing experiment was given in this paper. The high temperature FBG strain sensor was installed in the apparatus, the internal temperature of experimental apparatus was controlled from -20 to 300°C accurately, and strain loading was given by the counterweight, then the data was recorded through electrical resistance strain measurement and optical sensing interrogator. Experimental data result shows that the high temperature FBG strain experimental apparatus can work properly over 200°C. The design of the high temperature FBG strain experimental apparatus are demonstrated suitable for high temperature strain gauges and FBG strain sensors , etc, which can work under the temperature of -20 ~ 300°C, the strain of -1500 ~ +1500μepsilon and the wavelength resolution of 1pm.