Acoustic Emission of Composite Vessel

Generally for CNG vehicles, type II vessel, where the increase in used pressure and lighter weight are achieved through fiber-reinforced composite material, which is wrapped in hoopdirection on the steel liner is used. Since 1984, the U.S. experienced more than 80 cases of vehicle fuel tank-related accidents [3] and Korea also experienced 8 cases in which the CNG tank exploded; thus, there is a need for the development of inspection technology for highpressure fuel tanks. In the case of the U.S., the inspection technology of high-pressure fuel tanks were developed by DOD and NASA as an inspection technology for missile fuel tanks[4] but as the use of high-pressure fuel tanks for transport increased DOT executed a research on inspection technology for vehicles based on the research results of NASA and reported that among several NDT technology, Acoustic Emission(AE) has a possibility of being used as an inspection technology for vehicles[5,6]. The gas vessel, which is made of fiber-reinforced composite material, is unlike vessel made of only steel materials in that when the damage increases the acoustic generation activity increases but when the degree of damage increases even more, the acoustic generation activity rather decreases [7]. A study of defect detection and failure analysis for composite Materials using acoustic emission is progressing steadily [9-11,14].