| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1992: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1991: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
The properties of ultrasonic velocity through wood were examined to estimate moisture content of wood with moisture gradients by ultrasonic method.Following results were obtained.
1)The simple and good bonding methods were devised to get an accurate ultrasonic velocity. 2) When moisture gradient exists against the forward direction of ultrasound,the law of composite was applicable. When moisture gradient exists parallel to the forward direction of ultrasound, ultrasonic velocity was more dependent on the parts with the faster velocity. 3) Below the fibersaturation, ultrasonic velocity increased curvilinealy as moisture content decreased and the change percentage in ultrasonic velocity per unit moisture content was much more in the longituidnal direction than in the radial. The patterns of ultrasonic velocity-moisture content curves on a graph in a longitudinal and a radial for vapor-saturated specimens during drying were not so different with species. The patterns of ultrasonic velocity-moisture content curves in a longitudinal and a radial for water-saturated specimens during drying depended on the species,and could be divided into three groups. Consider the wood during drying as a composite material of woods with different moisture contents and the law of composite was applied,and the calculations agreed with measured valued. 4) In the LR and LT planes, ultrasonic velocity decreased as grain angle increased in softwoods and hardwoods,but in the RT plane the tendency of ultrasonic velocity on the annual rings in softwoods was different from that in hardwoods. 5) Ultrasonic velocity in a longitudinal was directly proportional to density in some speices, and in some it was inversely proportional to density, and in some no correlation was found between them.
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