油热处理对竹材声学振动性能的影响

Effect of Oil Heat Treatment on the Acoustic Vibration Performance of Bamboo

为探究油热处理对竹材声学振动性能、尺寸稳定性的影响规律,减少竹乐器在使用过程中出现开裂、变形,从而导致音质受损的不利影响,以大豆油为加热介质对竹材进行热处理,热处理温度分别为140、170、200℃,加热时间分别为2 h和4 h,利用双通道快速傅里叶变换分析仪得到试件处理前后的振动频谱图,读取其前五阶弯曲振动频率,分析声学振动性能参数,研究油热处理对竹材声学振动性能、尺寸稳定性的影响。处理后竹材的比动弹性模量(E_(sp))、声辐射品质常数(R)有明显提高,密度(ρ)、声阻抗(ω)、动力学损耗角正切(tanδ)和E/G呈下降趋势,声学振动效率得到提高。其中,经200℃、4 h处理后带有竹节的竹材声学振动性能提升最大,E_(sp)增幅为29.20%、ρ降幅为15.12%、R增幅为33.75%、ω降幅为3.41%、tanδ降幅为40.52%,E/G降幅为2.33%。最小体积干缩率和最大抗吸湿膨胀率分别为0.33%、56.95%,体积干缩率和体积吸湿膨胀率随处理时间和温度的增大而减小。结果表明,当油热处理时间为200℃,时间为4 h时,试件的声学振动性能得到了较好的改善,油热处理对竹材声学振动性能和尺寸稳定性的提升有积极作用。

In order to explore the impact of oil heat treatment on the acoustic vibration performance and dimensional stability of bamboo materials,and to reduce the adverse effects of cracking,deformation,and damage to sound quality of bamboo musical instruments during use,the experiment used soybean oil as the heating medium to heat treat bamboo,with heat treatment temperatures of 140℃,170℃,and 200℃and heating times of 2 and 4 hours.The vibration spectrum of the specimens before and after treatment was obtained using the dual channel FFT analyzer,and took the first to fifth bending vibration frequencies.Its acoustic vibration performance parameters were analyzed to study the effect of oil heat treatment on the acoustic vibration performance and dimensional stability of bamboo.After treatment,the specific dynamic modulus of elasticity(E_(sp))and sound radiation quality constant(R)of bamboo had significantly increased,and the density(ρ),acoustic impedance(ω),dynamic loss angle tangent(tanδ),E/G showed a downward trend,and the acoustic vibration efficiency had been improved.After being treated at 200℃for 4 hours,the materials with bamboo nodes showed the greatest improvement in acoustic vibration performance,with an increase in E sp of 29.20%,a decrease inρof 15.12%,an increase in R of 33.75%,a decrease inωof 3.41%,a decrease in tanδof 40.52%,and a decrease in E/G value of 2.33%.The minimum volume dry shrinkage and maximum anti hygroscopic expansion were 0.33%and 56.95%,respectively.The volume dry shrinkage and volume hygroscopic expansion decreased with increasing treatment time and temperature.Results showed that when the oil heat treatment time was 200℃and the time was 4 hours,the acoustic vibration performance of the specimens was better improved.Oil heat treatment had positive effects on improving the acoustic vibration performance and dimensional stability of bamboo.