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ブナ材を実験材料として、濃度を-50～+100℃の範囲で変化させたとき、1MHzの周波数のもとで、木材の力学的減衰におよぼす水分の影響について検討を行った。木材の力学的減衰の極大が、-10～-20℃の低温側に認められる。また、全乾から含水率約6％に至るまで、力学的減衰の極大値の温度の位置はほとんど変化しないが、含水率約6％以上で、含水率の増加とともに、その位置は低温側へ移動する。これは、木材への水...分の吸着の機構と密接に関係するものと考えられる。
The dynamic mechanical behavior of Buna-wood (Fagus crenata Blume) has been investigated as a function of temperature at a frequency of ultrasonic region. The ultrasonic attenuation in wood specimen was measured by means of pulse transmission method for a 1MHz-longitudinal wave. The testing temperatures ranged from near -50°C to as high as 100°C, and the moisture contents of wood specimens were from almost 0% (oven-dry) to 21%. Main results obtained are as fcllows： (1) The maximum mechanical damping of wood was observed at low temperatures(-10 - -20°C). The occurrence of the maximum damping may be largely associated with the action of moisture which is adsorbed on wood substances. (2)The position of the maximum mechanical damping in wood shifted with moisture content. At moisture contents below about 6%, the position of the maximum damping was situated near -10°C, and at moisture contents greater than about 6%, this position shifted to lower temperatures with increasing moisture content. This behavior is believed to be associated with the mechanism of the adsorption of moisture in wood. (3) For a high frequency of 1 MHz, the shift to lower temperatures of the position of the maximum mechanical damping caused by the adsorption of moisture on wood became smaller, as compared to the results obtained at the low frequency range of 3.5 Hz to 110 Hz.続きを見る
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Mendeley出力
木材学会誌21(7)