Structural Health Monitoring Method For Cryogenic Composite Tank

Composite materials have been widely used in the fields of aeronautics and astronautics, and have been one of the primary materials of rocket structures. Due to the excellent properties, the use of carbon fiber composite materials for Reusable Launch Vehicle fuel tank has become the research focus of the aviation countries in recent years. In order to ensure the safe operation and to reduce the maintenance cost of the composite tank at ultra-low temperature environment, for the special composite tank, in this paper, a kind of structural health monitoring sensing system has been designed and used in cryogenic temperature based on ultrasonic guided wave method, The damage identification of cryogenic temperature composite materials by ultrasonic guided wave damage imaging method was successfully carried out. Its main research contents are as follows:First, the research status of the field of structural health monitoring was summarized, and the propagation theory of ultrasonic guided wave and the damage identification method of composite material low temperature tank were introduced. The mechanical properties of four kinds of adhesives (DW-1, Hysol(?) EA9395, Hysol(?) EA 9396 and Araldite) were compared by the cryogenic and room temperature experiments. The impedance value of the piezoelectric sensor (PZT-5A) at cryogenic temperature was tested in a period of 60 days. The experimental results show that the Araldite can be used as adhesive layer of the sensor for structure health monitoring at cryogenic temperature, and the selected piezoelectric sensor PZT-5A can also keep a good durability at cryogenic temperature.Then, a flexible sensor array was designed and produced by two installation methods. The flexible sensor array can be used to identify the damages in aluminum at room temperatures, and was tested by transmitting and receiving guided wave. The feasibility of the flexible sensor array was verified in cryogenic temperature,At last, the ultrasound guided wave damage diagnosis experiment was carried out on the composite plate at cryogenic temperature using the designed sensing system. Experimental results show that the flexible sensor array with Araldite adhesive can be used as a sensing system by combining the ultrasonic guided wave imaging method, which can identify the different degree of damage in the composite plate at cryogenic temperature.