Detection of wood defects using low acoustic impedance-based PZT transducers

Early detection of common defects in wooden structures is an important factor to avoid costly maintenance and improve the life expectancy of structures. A novel qualitative technique has been developed and evaluated for detecting near-surface abnormalities and defects in wooden structures. The proposed setup consisted of a piezoelectric ceramic lead zirconate titanate transducer and an impedance evaluation board. This setup is cost-effective and can be easily employed over various wooden structures. The proposed setup was evaluated on a polymeric material with a debonding. The main experimental validations were conducted on wood specimens with unfilled carved cavities and also putty-filled holes. In addition, the setup was tested for the poor gluing in a wooden specimen. The measured impedance for each location was recorded and normalized to the reference baseline. The proposed setup could detect the cavities and putty-filled regions successfully. It also could detect the approximate geometry of defects. The glued and unglued regions were detected as well.