The Researches Of Wood Libration Characteristic By FEM

FEM is a pervasive and perfect method in simulating the process of experiment, applied in many field, especially like mechanism, civil engineering etc. its strong function is to simulate and forecast. This method remarkably changed the situation restricted by condition, when we experiment. The method of experiment by account and simulate, which applied to study dynamic characteristic in wood, has became one of the major research directions. Since FEM has the strong ability in simulating and universality in applying, it begins to be applied in researching the mechanics capability of woodiness material.According to research spruce and deal, this paper explore the feasibility that FEM was applied in study wood dynamic characteristic, construct a forecast model suited dynamic characteristic of no-lacuna, get the experience in apply FEM for wood, provide the available experience for analysis of libration characteristic in material.Major conclusions:1. According to the results, orthotropic model is available in measuring dynamic characteristic of wood, free libration is suitable with line elasticity situation, the FEM model for no-lacuna is successful.2. Compare the results from spruce and deal, we found that material character (texture, density distributing) markedly influenced the results; the paper also analyse the reason from the process of making the model and testing by FFT. All this is useful for perfect the FEM model.3. Compare the two methods by FFT and FEM, we found that as long as the FEM model is available, we could obtain more step frequency by FEM model, this point show that analyse by FEM has more advantage than by FFT.4. The deal model has error, the error brings on increase of analyse error, so we need to study and correct the model further.5. According to forecasting the bend libration frequency in radial direction and tangent direction and remarkable factor in material attribute, we obtained: libration frequencies in the two directions are different, material modulus of elasticity in axes direction influence the results most remarkably.