PURPOSE: To measure the moisture content of a sawn lumber conveniently with constant accuracy even under a condition where the vibration of sawn lumber is restricted by measuring the natural frequency of a second order or above.
CONSTITUTION: A sawn lumber 1, e.g. a structural member for building, is hit on one end face thereof by means of a hammer 2, for example, under a condition that the sawn lumber is restricted at the node and antinode of basic vibration (e.g. the sawn lumbers are stacked on crosspieces). Longitudinal oscillation sound thus generated is caught by means of a microphone 3 set on the end face and subjected to frequency analysis by means of an FFT(Fast Fourier Transformation) spectrum analyzer 4. Moisture content of sawn lumber is measured using the natural frequency of second order or above obtained by the frequency analysis.
ARIMA TAKANORI
SAKOTA TADAYOSHI
ARIMA TAKANORI
SAKOTA TADAYOSHI