杉木木材微观结构与抗弯性能的构效关系

Structure-property relationship between microstructure and bending properties of Chinese fir wood

摘要

【目的】杉木是我国重要的速生结构用材树种，抗弯性能是其结构安全评价的核心指标。而抗弯性能本质上由木材微观结构决定。阐明杉木木材微观结构与抗弯性能的构效关系，可以为杉木木材抗弯性能快速评估、加工改良以及杉木遗传改良措施实施提供科学依据。【方法】以江西省宜春市年珠林场 30 年以上人工林杉木为对象，沿径向区分心材与边材，利用光学显微镜、X 射线衍射仪、应力波检测仪及万能力学试验机等，系统获取壁腔比、微纤丝角、结晶度等微观结构因子及动态/静态抗弯性能指标。通过普通线性和多元线性回归分析，分别构建应力波波速、微观结构因子与抗弯性能的关系模型。【结果】杉木边材呈现“高壁腔比（较心材高 27.0%）、高结晶度（较心材高 14.6%）、低微纤丝角（较心材低 21.7%）”的特征，其动态弹性模量、抗弯弹性模量和抗弯强度较心材分别提升 5.9%、7.1% 和 12.4%。应力波波速与抗弯性能显著相关（ R² 为 0.66 ~ 0.69），壁腔比与抗弯性能的拟合度最高（ R² = 0.67）。多元线性回归模型的 R² 为 0.67 ~ 0.71，表明壁腔比、微纤丝角与结晶度共同作用于抗弯性能，其中壁腔比相对贡献最高（标准化系数 β 为 0.49 ~ 0.59），结晶度（ β 为 0.19 ~ 0.28）与微纤丝角（ β 为−0.18 ~ −0.14）次之。【结论】杉木木材抗弯性能由微观结构因子共同决定，高壁腔比、低微纤丝角和高结晶度有利于获得优异抗弯性能；应力波波速与抗弯性能具较好的相关关系，可作为抗弯性能快速评估的重要指标；多元线性回归模型量化了微观结构因子对抗弯性能的共同影响作用和相对贡献，其中壁腔比是影响抗弯性能的主导因子。

Abstract

[Objective] Chinese fir (Cunninghamia lanceolata) is one of the most important fast-growing structural timber species in China. Its bending properties are key indicators for evaluating the structural safety of wood materials and are fundamentally determined by the wood microstructure. Clarifying the structure–property relationships between microstructural characteristics and bending properties can provide a scientific basis for rapid assessment, processing modification, and genetic improvement of Chinese fir wood. [Method] Chinese fir trees aged over 30 years from a plantation in Nianzhu Forest Farm, Yichun, Jiangxi Province, China, were selected as the study material. Heartwood and sapwood were distinguished along the radial direction. Microstructural parameters, including wall-to-lumen ratio, microfibril angle, and crystallinity, together with dynamic and static bending properties, were determined using optical microscopy, X-ray diffraction, stress-wave testing, and a universal testing machine et al. Ordinary linear regression and multiple linear regression analyses were performed to establish predictive relationships between stress-wave velocity, microstructural factors, and bending properties. [Result] Compared with heartwood, sapwood exhibited a wall-to-lumen ratio 27.0% higher, a crystallinity 14.6% higher, and a microfibril angle 21.7% lower. The dynamic modulus of elasticity (MOE_d), modulus of elasticity (MOE) in bending, and modulus of rupture (MOR) of sapwood were 5.9%, 7.1%, and 12.4% higher than those of heartwood, respectively. Significant relationships were observed between stress-wave velocity and bending properties, with R ² ranging from 0.66 to 0.69. Among the individual microstructural factors, the wall-to-lumen ratio showed the strongest relationship with bending properties (R ² = 0.67). The multiple linear regression models yielded R ² values ranging from 0.67 to 0.71, indicating that wall-to-lumen ratio, microfibril angle, and crystallinity jointly affected bending properties. The standardized regression coefficients showed that the wall-to-lumen ratio had the greatest relative contribution (β of 0.49–0.59), followed by crystallinity (β of 0.19–0.28) and microfibril angle (β ranged from −0.18 to −0.14). [Conclusion] The bending properties of Chinese fir wood are governed by its microstructural factors. A higher wall-to-lumen ratio, lower microfibril angle, and higher crystallinity are associated with superior bending performance. Stress-wave velocity showed relatively strong relationships with bending properties and can therefore serve as an effective indicator for rapid evaluation of bending properties. The multiple linear regression models quantitatively characterized the combined effects and relative contributions of microstructural factors, with wall-to-lumen ratio identified as the dominant factor influencing bending properties.

关键词

杉木 / 木材力学 / 微观结构 / 抗弯性能 / 壁腔比 / 微纤丝角 / 结晶度 / 多元线性回归分析

Key words

Cunninghamia lanceolata / wood mechanics / microstructure / bending properties / wall-to-lumen ratio / microfibril angle / crystallinity / multiple linear regression analysis

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基金资助

国家重点研发计划课题(2023YFD2200501)