Detection of Void and Crack Defects in Type IV Hydrogen Storage Vessels by Microwave Technique

Abstract

Non-destructive testing based on microwave technique has been developing rapidly. In the present study, microwave-based method was used to detect void and crack defects in the carbon fiber composite wound layer of type IV hydrogen storage vessels. Taking advantage of a vector network analyzer, the reflection coefficient S11 of type IV hydrogen storage vessel samples without defects and with a void or a crack defect in the composite wound layer was measured. The defect-containing vessels exhibited S11 values much different from those of vessels without defects, according to which the defects can be detected. Additionally, identification of the two defects can be realized by analyzing the S11 values, as the void gives rise to more reflection of microwave than the crack. During the inspection, only when the horn antenna is against the defect does the S11 show significant changes, suggesting the detection sensitivity of the method. This study lays a solid foundation for the development of microwave inspection of defects in the composite wound layer of type IV hydrogen storage vessels.