西加云杉木材音板剪切模量的频率法测试分析

The Frequency Method for Measurement and Evaluation of Shear Modulus of Picea Sitchensis Soundboard

云杉类树种是完美的乐器共鸣资材,故以西加云杉径切板音板试材为研究对象,依据板的弯扭理论,用振动频率法实测试材在自由支承方式下的第1阶扭转频率值,测算得到剪切模量值;并用声学法进行了同步验证试验分析。结果表明,试材的测量值达到使用要求;频率法测量结果与声学法一致,具有快速、准确、重复性好等优点。该研究对我国开展钢琴等乐器音板用材的无损检测质量分等及其选材有一定的参考价值。

Spruce is the perfect tree species for resonating instrument material. In this paper, trail cutting board of Picea sitchensis was taken as studied material. The method used a vibration frequency to get the first order bending and torsional frequencies of free plate based on the theory of bending and torsion for plate and then shear modulus was calculated. Besides, acoustic method was applied for concurrent validation measurement and analysis. Main results are as follow： the measurement result of Picea sitchensis samples satisfy the use requirement; the measurement result by using frequency method is consistent with the measurement result by using acoustic method. In addition, this frequency method has advantages of rapidness, accuracy and high repeatability. This work can provide reference to nondestructive testing, quality assessment and selection of soundboard lumbers for musical instruments, such as piano.