桦木单板−金属铜网复合材料声学振动性能研究

Acoustic vibration performance of birch veneer-metal copper mesh composites

【目的】传统实木乐器音板的选材和用材都十分严格,然而当下我国优质木材资源紧缺,资源需求压力较大,开发可用作乐器音板的复合材料是缓解木材需求压力的有效途径。【方法】试验制备了双层、5层桦木单板分别与金属铜网复合的两种厚度复合材料。在分析复合材料尺寸稳定性的基础上,利用双通道快速傅里叶变换频谱分析仪测试其声学振动性能,研究桦木单板铺装方向、金属铜网添加位置与添加层数对声学振动性能的影响,并采用综合评分法比较了复合材料与西加云杉的声学性能。【结果】加入金属网后制备的双层、5层桦木单板复合材料的抗湿胀系数最高分别为80.00%与88.09%,胶合界面的增加提升了复合材料的抗湿胀系数。桦木单板铺装方向影响复合材料的E_(L)/E_(R)值,以单板纹理平行铺装的双层单板复合材料E_(L)/E_(R)值为29.09,以单板纹理交错铺装的双层单板复合材料E_(L)/E_(R)值为0.99。加入2层金属铜网的5层复合材料,具有接近西加云杉的振动效率品质和更为优秀的音色,其抗湿涨系数平均值达到87.61%、纵向比动弹性模量达到20.20 GPa、声辐射品质常数达到6.13 m/(Pa·s^(3))、声阻抗为3.29 Pa·s/m、E/G值达到29.63。【结论】通过与西加云杉木材的比较表明,复合材料的声学振动性能基本能达到一般乐器的要求,并且具有良好的尺寸稳定性,是传统实木音板的良好替代材料。

[Objective]The selection and use of traditional solid wood musical instrument soundboards are very strict.However,at present,there is a shortage of high-quality wood resources in our country,and the pressure on resource demand is relatively high.The development of composite materials that can be used as musical instrument soundboards is an effective way to alleviate the pressure on wood demand.[Method]2-layer and 5-layer birch veneer composite materials with two thicknesses and metal copper meshes were prepared in the experiment.On the basis of analyzing the dimensional stability of composite,the acoustic vibration performance of the composite was tested by the dual channel Fast Fourier Transform Spectrum Analyzer(FFT),and the effects of the direction of birch veneer pavement,the location and number of layers of metal copper mesh on the acoustic vibration performance were studied.The acoustic performance of the composite was compared with that of Sitka spruce by the comprehensive scoring method.[Result]The highest coefficient of moisture expansion resistance of double layer and five layer birch veneer composites prepared with metal mesh was 80.00%and 88.09%,respectively.The increase of bonding interface improved the coefficient of moisture expansion resistance of the composites.The direction of birch veneer pavement affected the E_(L)/E_(R) value of composite materials.The E_(L)/E_(R) value of double-layer veneer composite materials paved with parallel veneer texture was 29.09,and the E_(L)/E_(R) value of double-layer veneer composite materials paved with interlaced veneer texture was 0.99.The 5-layer composite added with two layers of metal copper mesh had a vibration efficiency quality close to that of Sitka spruce and a better timbre.Its moisture resistance coefficient reached 87.61%,the longitudinal specific dynamic modulus of elasticity reached 20.02 GPa,the sound radiation quality constant reached 6.13 m/(Pa·s^(3)),the sound impedance was 3.29 Pa·s/m,and the E/G value reached 29.63.[Conclusion]The comparison with Sitka spruce shows that the acoustic vibration performance of the composite material can basically meet the requirements of general musical instruments,and it has good dimensional stability,which is a good substitute for traditional solid wood soundboards.