A novel method for estimating the wood moisture content above the fiber saturation point (FSP) is proposed, and the method performance is confirmed. Previous studies have highlighted that there is a negative linear correlation between the specific dynamic Young’s modulus (log (E/ρ)) and tangent loss (log (tanδ)) of clear small wood specimens. We confirm that this correlation can be obtained for air-dried commercial lumber from Japanese cedar, or sugi (Cryptomeria japonica), via experimental analysis. The best-fit linear regression line of this correlation only changes by the apparent density above the FSP (i.e., only by the moisture content of the specimen) when E and tanδ are kept constant in this high moisture content range. Here, we derive an equation to calculate the moisture content using log (E/ρ) and log (tanδ) based on the regression line of sugi wood at the FSP. A 45-day drying test was conducted on 23 green lumber specimens, with the E/ρ and tanδ values calculated from the natural resonance frequency fr, the logarithmic decrement λ and dimensions at various drying stages. The estimated moisture contents are in good agreement with the measured values, confirming the performance of proposed moisture content method.

中文翻译：

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使用比动态杨氏模量和切线损耗之间的相关性估算杉木中纤维饱和点以上的水分含量

提出了一种新的估计纤维饱和点（FSP）以上木材水分的方法，并确认了该方法的性能。先前的研究强调，透明小木材样品的比动态杨氏模量（log（E /ρ））与切线损耗（log（tanδ））之间存在负线性关系。我们证实可以通过实验分析从日本雪松或sugi（日本柳杉）风干的商用木材中获得这种相关性。当E和tanδ在此高水分含量范围内保持恒定时，这种相关性的最佳拟合线性回归线仅改变FSP上方的表观密度（即仅改变样品的水分含量）。这里，我们基于FSP上杉木材的回归线，导出了使用log（E /ρ）和log（tanδ）来计算水分含量的方程式。在23个生材样品上进行了45天的干燥测试，其E /ρ和tanδ值是根据自然共振频率fr，对数递减λ和各个干燥阶段的尺寸计算得出的。估计的水分含量与测量值非常吻合，证实了所提出的水分含量方法的性能。