Study On The Preparation And Acoustic Vibration Properties Of Birch Veneer/Fiberglass Composites

In the face of the serious shortage of musical instrument sound board material resources in our country,it is very necessary to improve the utilization rate of wood to achieve inferior wood use and to find new materials to replace the musical instrument wood sound board materials.The test used glass fiber as the reinforcing materials and birch veneer as the base materials.The birch veneer/glass fiber composite materials was designed according to the veneer laminated wood structure.The effects of laying structure and hot pressing process conditions of glass fiber cloth on the acoustic vibration properties of composites were investigated.Finally,the acoustic vibration properties of composites were evaluated comprehensively by comprehensive evaluation method,and compared with spruce used in common musical instruments.The main findings of the paper are as follows:(1)The acoustic vibration performance of the composites laid under the surface veneer with glass fiber cloth were better than that of the composites laid with fibers close to the core veneer.The E/??E/G?R?v??/? of composites A placed under the surface veneer with a layer of glass fiber cloth wree 8.7%,17.8%,4.87%,4.27%,8.5%higher than those of composite B with one layer of glass fiber cloth on one side of core veneer respectively.Tan? of composite A is 4.34%smaller than that of composite B?The E/??E/G?R?v??/? of the composite C covered with two layers of glass fiber cloth under the upper and lower surface veneer are higher than that of the composite D laid on both sides of the core veneer with two layers of glass fiber cloth.(2)The number of glass fiber cloth layers has a significant effect on the acoustic vibration properties of birch veneer/glass fiber composites.The acoustic vibration performance of the composites with glass fiber cloth were better than that those of the composites without glass fiber cloth.The E/??E/G?v??/? of the composites with two layers of glass fiber cloth reached the maximum,which increased by 46.8%,21.91%,20.1%?25.79%,respectively compared with the composite materials without glass fiber cloth.The results show that the acoustic vibration properties of the composites with two layers of glass fiber cloth were better than those with one layer,three layers and four layers of glass fiber cloth respectively.(3)On the basis of single factor experiments,the test results of acoustic vibration properties of composites were fitted by quadratic polynomial regression with Design-Expert software,and the factors that had no significant effect on the model were eliminated.The regression equations and response surface models of E/??E/G?R?tan??v were established,and the optimum process parameters were determined as follows:hot pressing temperature was 89?,hot pressing pressure was 1.3 MPa,and sizing amount was 180 g·m-2.(4)Comparing the acoustic vibration performance of composites with that those of sitka spruce,which are commonly used for musical instruments.It was found that the E/??E/G?v of composite material C,which has excellent acoustic vibration performance,were close to those of sitka spruce.It shows that birch veneer/glass fiber composite has the possibility to replace the soundboard made of solid wood.(5)By using the comprehensive scoring and comprehensive coordinate method to comprehensively evaluate the acoustic vibration performance of birch veneer/glass fiber composites,it can be seen that the acoustic vibration performance of the composites with glass fiber laid on the surface veneer were better than that of the fiber glass cloth near the core.The composite materials with two layers of glass fiber cloth have the best acoustic vibration performance.