Abstract The relationship between grain angle and wood properties has not been focus of researches in wood industry. The aim of this study was to establish grain angle variations in commercial Eucalyptus logs and their effects on physical-mechanical wood properties. Wood maximum angular deviation (MAD) was correlated with density, volumetric shrinkage, compressive strength parallel to grain, flexural strength and stiffness as determined by bending and acoustic methods in wood of seven Eucalyptus grandis × Eucalyptus urophylla clones at 13 years old. The relationship between MAD at pith-bark and base-top positions and its effect on the physical and mechanical properties were evaluated. Amplitude of MAD values was small for the seven clones, and the mean was 6.2°. The grain deviation decreased by only 8% in base-top direction, and the correlations among MAD and three logs heights were small and negative (r = −0.13). MAD values presented an increasing trend of 33% in pith-bark direction, with a small positive correlation (r = 0.42). Basic density (BD) presented a significant correlation with the MAD (r = 26). There was no significant correlation between the MAD and volumetric shrinkage, mechanical properties and modulus of elasticity dynamic (determined by stress wave timer, ultrasound or transverse vibration).

中文翻译：

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桉树木纹角度变化及其与物理力学性质的关系

摘要 木纹角度与木材特性的关系一直不是木材工业研究的重点。本研究的目的是确定商业桉木原木的纹理角度变化及其对物理机械木材特性的影响。木材最大角度偏差 (MAD) 与密度、体积收缩、平行于纹理的抗压强度、弯曲强度和刚度相关，这是通过弯曲和声学方法在 13 岁的 7 个大桉 × 尾叶桉无性系木材中测定的。评估了髓-树皮和基顶位置的 MAD 之间的关系及其对物理和机械性能的影响。7个克隆的MAD值幅度较小，平均值为6.2°。基顶方向的纹理偏差仅减少了 8%，并且 MAD 与三个对数高度之间的相关性很小且为负（r = -0.13）。MAD 值在髓-树皮方向呈 33% 的增加趋势，呈小正相关（r = 0.42）。基本密度 (BD) 与 MAD 显着相关 (r = 26)。MAD 与体积收缩、机械性能和弹性动态模量（由应力波计时器、超声波或横向振动确定）之间没有显着相关性。