Grenadilla wood (Dalbergia melanoxylon Guill. & Perr.) is a hardwood species found in Tanzania, Mozambique, and other countries in the tropical part of Africa, especially in the Eastern-Central region. Thanks to its high density and good hygro-scopic stability, it is used in the making of various musical instruments and fine furniture. Due to the scarcity of published data on this wood species, more studies on its properties are needed to improve its processing and use, and even to search for sustainable alternative materials as its trade is increasingly limited by new regulations. This work is focused on the hygromechanical properties, which hold an important role in the applications of this wood: diffusion coefficients and adsorption-desorp-tion curve (both measured at T = 20 • C), swelling-shrinkage coefficients and full orthotropic elastic constants using an ultrasonic method. Results show that grenadilla wood possesses small water diffusion coefficients (from 1.54 ± 0.49 × 10 −7 cm 2 ∕s in T direction to 4.58 ± 0.84 × 10 −7 cm 2 ∕s in L direction), which is probably related to its high density (1250.0 ± 26.2 kg∕m 2); unique equilibrium moisture content (sorp-tion) curve with a lower fiber saturation point (0.173 ± 0.003); smaller swelling-shrinkage coefficients (0.20 ± 0.03 and 0.32 ± 0.05 in T and R directions, respectively); and elastic constants lower in the longitudinal direction (15.56 ± 1.79 GPa) and higher in the transverse ones (5.10 ± 0.46 GPa and 4.05 ± 0.35 GPa in R and T directions, respectively) than what could be expected with a standard model based on the density only. Several explanations were described here, from the effects of a high extractive content to the possibility of a high microfibril and/or fiber angle.

中文翻译：

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石榴木 (Dalbergia melanoxylon) 的吸湿机械特性

Grenadilla wood (Dalbergia melanoxylon Guill. & Perr.) 是一种在坦桑尼亚、莫桑比克和非洲热带地区的其他国家，尤其是东部-中部地区发现的硬木树种。由于其密度高，吸湿稳定性好，用于制作各种乐器和精美家具。由于缺乏有关该木材种类的已发表数据，需要对其特性进行更多研究以改进其加工和使用，甚至在其贸易越来越受到新法规限制的情况下寻找可持续的替代材料。这项工作的重点是在这种木材的应用中起着重要作用的湿机械特性：扩散系数和吸附-解吸曲线（均在 T = 20 • C 下测量），使用超声波方法计算膨胀收缩系数和全正交各向异性弹性常数。结果表明，石榴木具有较小的水扩散系数（从 T 方向的 1.54 ± 0.49 × 10 -7 cm 2 ∕s 到 L 方向的 4.58 ± 0.84 × 10 -7 cm 2 ∕s），这可能与其高密度（1250.0 ± 26.2 kg∕m 2）；独特的平衡水分含量（吸附）曲线，具有较低的纤维饱和点 (0.173 ± 0.003)；较小的膨胀收缩系数（在 T 和 R 方向分别为 0.20 ± 0.03 和 0.32 ± 0.05）；纵向的弹性常数 (15.56 ± 1.79 GPa) 和横向的弹性常数 (R 和 T 方向分别为 5.10 ± 0.46 GPa 和 4.05 ± 0.35 GPa) 比基于仅密度。