Abstract:

It aimed at offering technique reference for studying the product line of wood strength's real time rating. It adopted the nature frequency measurement system of fast fourier transform(FFT) to auto_measure the dynamic modulus of elasticity(DMOE), and adopted mechanical test machine to measure the static modulus of elasticity(E_S) of air-drying lumber which were buying from the market. The species are including Fraxinus mandshurica, Pinus koraiensis, Juglans mandshurica. Some results were gained and described as follows: 1)The correlation between every species' E_S and transverse vibration DMOE(E_F), longitudinal vibration DMOE(E_L) are significant. 2)For whole species, the correlation between E_S and E_F, E_L are more significant than that the single sort of species'. It indicated that the method of FFT is universal. 3)The correlations between E_S and sample's density(ρ) are significant, but the correlation coefficient of E_S and ρ is lower those between E_F, E_L and E_S. It indicated that wood E_S is more exact by the method of estimating based on FFT measuring than the method of estimating based on density.

Key words: lumber, non-destructive test, dynamic modulus of elasticity(DMOE)