鹅掌楸天然林木材物理力学及垂直变异特性研究

A Study of Wood Physical and Mechanical Properties and Vertical Variation Characteristics of Natural Liriodendron chinense Forest

对鹅掌楸天然林木材物理力学与垂直变异进行了测定分析,结果表明:鹅掌楸天然林木材的基本密度、全干密度和气干密度分别为0.352 g·cm^(-3)、0.396 g·cm^(-3)和0.558 g·cm^(-3),基本密度、全干密度和气干密度性状在垂直方向均为上部>中部>下部,各部位的差异极显著。木材气干状态时体积干缩率为7.21%,全干状态时干缩率为2.54%;从全干到气干时,木材体积湿胀率为4.54%;从气干到吸水饱和时,木材体积湿胀率为12.41%;在垂直方向上,木材的体积干缩率为上部>下部>中部,而体积湿胀率为上部>中部>下部,且不同部位出体积干缩湿胀性在垂直方向上存在差异性显著。木材的顺纹抗压强度和抗弯强度分别为34.7 MPa和53.22 MPa;横面、弦面和径面的硬度分别为3.49 kN、2.55 kN和2.45 kN;在垂直方向上,木材的顺纹抗压强度、抗弯强度、横面硬度和径面硬度表现出上部>中部>下部的规律。由此可知,鹅掌楸天然林木材密度属轻中等水平,顺纹抗压、抗弯性能及硬度属一般水平,是适合加工利用的树种。

Abstract： Studies were made of the physical and mechanical properties and its vertical variation of Liriodendron chinense wood from natural forest. The results showed the wood basic density （ BD）, over-dry density（DD）and air-dry density（AD）were respectively 0. 352 g·cm^-3 ,0. 396 g·cm^-3 and 0. 558 g·cm^-3. The characteristics of BD,DD and AD displayed the upper 〉 middle 〉 lower parts in the vertical direction, and the difference was very significant. The wood volume shrinkage ratio of natural L. chinense forest under air-drying condition were 7.21%, while under oven-dry condition, it was 2. 54% . The wet expansion rate of wood volume was 4. 54% from oven-dry to air-dry, while the volume wet expansion rate of wood was 12. 41% from air-dry to water absorption. The wood shrinkage was the upper 〉 the lower 〉 the middle part in the vertical direction, while the volume part 〉 the lower part. The volume dry shrinkage dampness wetting rate was the the upper part 〉 the middle was different in the vertical direction. The compressive strength and flexural strength of the wood were 34. 7 MPa and 53.22 MPa, respectively. The hardness of the transverse, chord and diameter surfaces were 3.49 kN,2.55 kN and 2.45 kN, respective- ly. In the vertical direction, the CIS compressive strength, bending strength, transverse hardness and the hardness of the diameter surface of wood showed the rule of the upper part 〉 the middle part 〉 the lower part. It was proved that wood density of natural forest of L. chinense was a light medium level, and its CIS compression, bending resistance and hardness were general level. The wood of L. chirtertse was suitable for processing and utilization.