Polar scan technique for material characterization and identification of new operating regimes

The quest for more sophisticated methods imparts a significant challenge in the field of NDT and material characterization. In this paper, we present and discuss experimental polar scans of typical carbon-based composite materials, recorded with different shock wave transducers. Besides the well-known measurements performed in transmission (T) and double through transmission (TT), we introduce polar scans of both the backscattered and the double-double through transmission (TTTT) signal. The amplitude as well as the time of flight values (of the peak amplitude) are recorded as function of the scanned solid angle. Because of the frequency dependence of the recorded polar scans, the observed patterns cannot be linked to bulk waves, but rather to discrete plate modes. Furthermore, it is observed that the backscattered signal is dependent on the layer orientations of the material and is highly sensitive to the frequency of the incident pulse. Comparison between the results obtained with T, TT and TTTT method indicates that more detailed information can be obtained when employing the TTTT method.

ISBN:978-972-8826-26-0

Jaar van publicatie:2012

Trefwoorden:polar scan, NDT, carbon fibre reinforced composites, backscatter, 4T recording