SIMPLIFIED CLASSIFICATION OF SAWN WOOD ACCORDING TO GRADE

摘要

PURPOSE: To simply classify the strength and static Young's modulus of sawn wood by using a natural oscillation frequency of a third order or higher even under a condition that the oscillation of a log is restricted. ;CONSTITUTION: In a state that cut down logs 1 are left on the ground or that their oscillation is restricted such as in a state that they are heaped up as shown is the figure in a raw lumber market, that is to say, under a condition that the position of every node and every antinode of fundamental oscillations of the logs is restricted, longitudinal oscillation sounds generated when one edge of every log 1 is hit by a hammer 2 or the like are caught by a microphone 3 which is placed on the other edge. Then, in a simple classification method, a natural oscillation frequency of a third order or higher out of resonance frequencies obtained by analyzing the frequency by an FET(Fast Fourier Transformation) spectrum analyzer 4 is adopted, and the strength and static Young's modulus of sawn wood are estimated.;COPYRIGHT: (C)1995,JPO