Quantification of the “Tapping” Technique for the Detection of Edge Defects in Laminated Plates

A miniature piezoelectric transducer has been used to sense both details of the loading history and features of the ringing response in tapping tests conducted on bonded aluminum and graphite/epoxy plates containing artificial flaws. Either the loading or the ringing phase of the resulting output records exhibits significant differences for loading occurring over, as opposed to off, the flaw. When the data are examined in the frequency domain, it is found that major details are beyond the audible range of frequencies.