Flaw detection in a multi-material multi-layered composite: Using FEM and air-coupled UT
Ceramic tiles are the main ingredient of a multi‐layer multi‐material composite being considered for the modernization of tank armors. The high stiffness, low attenuation, and precise dimensions of these uniform tiles make them remarkable resonators when driven to vibrate. This study is aimed at modeling the vibration modes of the tiles and the composite lay‐up with finite element analysis and comparing the results with the resonance modes observed in air‐coupled ultrasonic excitation of the tiles and armor samples. Defects in the tile, during manufacturing and∕or after usage, are expected to change the resonance modes. The comparison of a pristine tile∕lay‐up and a defective tile∕lay‐up will thus be a quantitative damage metric. The understanding of the vibration behavior of the tile, both by itself and in the composite lay‐up, can provide useful guidance to the nondestructive evaluation of armor panels containing ceramic tiles.