Study on detecting lumber damage using acoustic radiation

The method using the sound caused by knocking the lumber to detect its damages has applied for a long time, but it mostly depends on the people’s experience and the subjective elements which could cause great errors to the judgment of damage. This paper analyzed the relationship between the lumber vibration impulse response and acoustic radiation properties. The analysis results showed that lumber acoustic radiation time-domain and frequency-domain signal characteristics depend on the structural characteristics of lumber. By testing the lumber acoustic radiation properties, it was known that the differences of damage and its location could change the main vibration frequency, energy of the lumber and waveform of time-domain. Based on these characteristics, it is effective to identify the damage of the lumber and its location.