Determining Dynamic Viscoelasticity And Shear Modulus Of Wood Composites

In this article, the goal is to provide a quick method to determine the dynamic viscoelasticity and shear modulus for wood composites. Detection theory and detection systems development were explored to determine a method for obtaining the dynamic viscoelasticity and shear modulus of wood composites. The development of the theory and testing methods will provide benefits in many other related research areas. These methods will provide a consistent theoretical and technical basis for scientific evaluation of stiffness, strength, seismic, vibration isolation, acoustic noise, and other characteristics of wood composites, and play a guiding role in production quality control.The application of cantilever-beam free vibration theory on testing dynamic viscoelasticity and shear modulus of wood composites is one of the significant developments for this thesis. First of all, the relationships between free vibration characteristic parameters with the shear modulus and dynamic viscoelasticity of materials were determined for wood composite specimens, using the Kelvin model theory, the Euler-Bernoulli beam theory, and the vibrating reed theory. Specimen dimensions with physical and mechanical properties were included in deriving the formulas for shear modulus, storage modulus, loss modulus, and loss angle. This information provided the theoretical basis for determining test values. Secondly, the theoretical studies provided a basis to build a cantilever beam vibration system and method that can detect necessary characteristic parameters. Finally, the result is a method to test and determine the dynamic viscoelasticity and the shear modulus of wood composites. The following conclusions were obtained by analyzing the experimental data using correlation analysis software by Statistical Package for the Social Science (SPSS). The logarithmic reduction factor is an important parameter for the dynamic viscoelasticity and shear modulus testing of wood composites. There is a good linear correspondence between dynamic viscoelasticity and density for the wood materials tested. The correlation coefficients were0.86and0.65respectively between the storage modulus and density, loss modulus and density. Dynamic viscoelasticity of wood materials is primarily influenced by composition and material arrangement, and has less to do with physical characteristics such as size, quality of the material. The storage modulus and loss modulus obtained by the cantilever free vibration method and the forced vibration method have significant correlation coefficients of0.87and0.84, respectively. Thus showing the cantilever-beam free vibration method to detect dynamic viscoelasticity of the wood composites is feasible. The shear modulus also correlates closely with material density. The linear correlation between the shear modulus and the cantilever dynamic modulus is significant, and the correlation coefficient is0.996, which means that the method to could be used to detect shear modulus of the wood materials.The research results shows that based on the cantilever free vibration principle can be used for rapid determination of dynamic viscoelasticity and shear modulus for wood composites. It is possible to use the test apparatus to determine the storage modulus, loss modulus, and shear modulus effectively for wood composites, and thus better evaluate the material’s stiffness, strength, seismic, vibration isolation, acoustic noise, and other performance characteristics with one test setup and apparatus.