高温热处理对尾叶桉木材声学振动性能的影响

Effect of High-temperature Heat Treatment on the Acoustic-vibration Performance of Eucalyptus urophylla

以N2为保护气体,对尾叶桉(Eucalyptus urophylla)木材进行热处理,热处理温度分别为170、190、210℃,保温时间分别为2、3、4 h,并分析处理前后其声学振动参数(比动弹性模量E/ρ、声辐射品质常数R、声阻抗ω、弹性模量与剪切模量之比E/G等)的变化,结果表明:经适当温度与保温时间的热处理后,尾叶桉处理材的E/ρ、R、E/G可得到不同程度的提高,而其ω则呈下降趋势,使得木材的声学振动性能得到有效改善。其中处理材的E/ρ的最大增幅为12.3%(190℃、2 h),其R的最大增幅为16.7%(210℃、3 h),其E/G的最大增幅为14.2%(210℃、4 h),其ω的最大降幅为6.0%(210℃、4 h)。总体结果表明,当热处理温度为210℃、保温时间为3 h时,尾叶桉木材的振动性能得到较好的改善。

The acoustic-vibration parameters ofEucalyptus urophylla,including specific Young’s modulus(E/ρ),coefficient of sound-radiation resistance(R),sound resistance(ω),and the ratio of Young’s modulus to the dynamic stiffness modulus(E/G),before and after heat treatment were measured and characterized.Conditions for the heat treatment included N2as the protection gas and temperatures of170℃,190℃,and210℃with holding times of2h,3h,and4h.The results showed that specific Young’s modulus,the coefficient of sound-radiation resistance,and the ratio of Young’s modulus to the dynamic stiffness modulus increased,whereas sound resistance decreased,thereby the heat treatment with proper temperature and suitable holding time improved the acoustic-vibration performance of the wood.The maximum increments were12.3%for specific Young’s modulus(190°C,2h),16.7%for the coefficient of sound-radiation resistance(210°C,3h),and14.2%for the ratio of Young’s modulus to the dynamic stiffness modulus(210℃,4h).Conversely,the maximum decrease in sound resistance was6.0%(210℃,4h).Overall,the acoustic-vibration performance ofE.urophylla was improved through heat treatment,while the best vibration performance was obtainedat210°Cwithaholdingtimeof3h.