Research On EFPI-FBG Hybrid Sensing Technology For Simultaneous Measurement Of High Temperature And Large Strain

With the advent of fiber and the development of fiber optic communication, fiber optic sensor has been becoming mature in recent years. And the technology popularization and formation of industry has also gradually become a reality. According with the demand of modern sensor technology, fiber optic sensors which have the potential to be widely applied in aero/astro-nautical Engineering and petrochemicals industry get continuous promotion and rapid development. However the monitoring system with characteristics of multi—parameter measurement and multi-measuring points installation requests the optic sensor to realize multi-parameter measurement in order to simplify the installation of sensors and transmission lines.In these areas, high temperature and large strain working condition hampers the application and popularization of optic fiber sensing technology. What's more, the cross-sensitivity of temperature and strain is also a big problem to solve. So, the research of the simultaneous measurement of multi-parameter based on the fiber optic sensing technology is necessary and important.Based on a deep analysis of the measuring principle of FBG and EFPI, this paper proposed a compound EFPI-FBG sensor, which can detect strain and temperature simultaneously. After specialized design, the measurement range of the sensor suffices the requirement of practical use. The main research work and achievement obtained of this project are:First,the design scheme of simultaneous measurement of strain and temperature system is presented based on the detailed analysis of the sensing principles and characteristics of FBG mad EFPI.And the simultaneous measuring principle has been analyzed profoundly. In the EFPI-FBG hybrid sensor,the FBG is used to measure temperature and the EFPI used to measure strain.The work of data acquisition and analysis processing of the strain and temperature signal can be completed using the identical demodulation system.Second.study on structural design and fabricating technology of the EFPI-FBG compound sensor is performed.Each structural parameter scope of the EFPI-FBG sensing head is offered.The encapsulation structure and dimension of the EFPI-FBG compound sensor are determined.The fabrication and encapsulation technological process of the sensor has been set down respectively.And we have manufactured the finished product of this new type of EFPI-FBG compound sensor successfully.Third, the experimental system of simultaneous measurement of strain and temperature using the EFPI-FBG compound sensor has been designed.The strain and temperature characteristics of the sensor have been tested and the result has verified the practicability of the simultaneous measuring system with temperature self-compensation. And realize the measurement of large strain under high temperature.