Tap testing of composites benchmarked with digital shearography

This paper reports on two non-destructive testing techniques employed to detect subsurface defects in composite materials of both the monolithic and sandwich types. Making use of the NDT techniques named on the title of this paper, Digital Shearography was used to benchmark the results obtained through the Tap Testing method. The tap testing was performed using the Mitsui Woodpecker WP-632AM, a hand held automated impact instrument that displayed the defects’ positional data (X-Y coordinates) on a PC in real time. The versatility and ease of use of the Woodpecker is abundantly demonstrated and the comparisons with the results obtained with Digital Shearography on the same test specimens have given an indication of its accuracy.