Identifying Void and Crack Defects in Type III Hydrogen Storage Vessels Based on Microwave Inspection

Abstract

Microwave technique has become a promising candidate for non-destructive testing. In this study, microwave-based method was used to inspect type III hydrogen storage vessels and to identify void and crack defects in the carbon fiber composite wound layer. Using a vector network analyzer, the reflection coefficient S11 of type III hydrogen storage vessel samples with no defects and with a void or a crack defect in the composite wound layer was measured. The defect-containing vessels had S11 values significantly different from those of vessels without defects, based on which the defects can be detected. Moreover, identification of the two defects can be achieved by comparing the values of S11, as the void results in more microwave reflection than the crack. During the inspection, only when the horn antenna is against the defect does the S11 show great changes, indicating the detection sensitivity of the method. This work provides new insights into inspection of defects in the of carbon fiber composite wound layer of type III hydrogen storage vessels.