木材薄板横纹压缩强化的微观结构变化与拉伸弯曲性能

Micro-Structure of Strengthened Wood Sheets by Compression Perpendicular to Grain and Its Stretch Bending Performance

以黑龙江产大青杨（Populus ussuriensis）刨切薄板为研究对象,用常温水浸泡至饱水状态,不经热软化预处理进行横纹压缩强化,经160、180℃高温定型处理1~24 h。通过扫描电镜观察横纹压缩强化前、后（未压缩材和压缩材）木材横、纵切面上的微观结构变化;分析横纹压缩强化前、后,木材拉伸、弯曲性能变化。结果表明：压缩材横切面上整体变形较均匀;横、纵切面上均未发现压缩裂纹或破坏;纵切面上,导管壁均有因压缩产生顺纤维方向的横向挤压折皱条纹;横切面上,大青杨压缩材管孔沿压缩方向变形最大。弯曲强度和断裂应力有所降低,最大应力时的应变平均值、断裂应力时的应变平均值,都随热处理时间的增加而下降。

Sliced wood sheets of Populus ussuriensis were dipped into water under normal temperature until water-saturated,then compressed from perpendicular to grain without heated softening pretreatment and form-fixed under 160 ℃ and 180 ℃ for 1-24 hours. The micro-structure at across-grain section and along-grain section of wood sheets before and after compression were examined with scanning electron microscope,and the pulling and bending performances of wood sheets before and after compression were analyzed. The entirety compression deformations of three species are relatively even and well-distributed, and there are no significant differences between the surface and the internal. There are no cracks or breaks at both acrossgrain and along-grain sections. The vessel deformation of P. ussuriensis along compression direction is the most obvious, and the average strain at maximum stress and the average strain at fracture stress both decrease with the increase of heat treatment duration.