Application of Fiber-optic Sensors to CFRP Pressure Tanks for Internal Strain Monitoring

초록

There are growing concerns on carbon fiber reinforced plastics (CFRP) due to their high specific strength and light weight for applications on many kinds of structures including aerospace structures like satellites, infrastructures like bridges, and special purpose structures requesting high level of engineering performances. Among those structures, CFRP pressure tanks are recently promising as an alternative of metal based pressure tanks that are being widely applied to many types of gas tanks for decades. In this paper, fiber-optic sensors, fiber Bragg grating (FBG) sensors in particular, are applied to a CFRP pressure tank with embedment in order to measure internal strains during the whole life cycle including fabrication, pressurizing, and final breakage. The tank is fabricated using filament winding processes and the pressurizing test is conducted with water to its final burst. During the test, all data from embedded FBG sensors and attached electric strain gauges (ESGs) are acquired to a laptop computer in real-time. Through the test, the applicability and validity of FBG sensors on CFRP pressure tanks are evaluated by comparing the experimental results from FBG sensors with those from both ESGs and FEM analysis. In conclusion, FBG sensors embedded into CFRP pressure tanks can successfully measure internal strains at both domes and cylinders and the results show good agreements with those from FEM analysis as well as ESGs. This means that FBG sensors can be one of good solutions to monitor internal strains of many kinds of pressure tanks, which are generally under severe environmental conditions like very high internal pressures and ultra-low temperatures, including CFRP pressure tanks by embedment.