背面裂隙对杨木胶合界面力学性能的影响

Influence of lathe checks on mechanical properties of poplar veneer bonding interface

采用微观数字散斑干涉技术和宏观剪切强度试验相结合,分析并讨论了杨木单板背面裂隙的存在对其胶合界面微观力学性能和宏观剪切强度的影响;采用淀粉糊、淀粉糊/木粉、豆胶3种封闭剂处理杨木胶合界面上的背面裂隙,探讨改性试样微观应变分布和宏观力学性能之间的关联。结果表明：存在背面裂隙的杨木单板胶合界面上的应变数值较大,达到1.5×10^-3～4.0×10^-3,复合材料整体的强度显著减小;不同封闭剂处理背面裂隙的试件,其胶合界面的应变显著大于未处理的试件;封闭剂处理后,杨木单板层积材干强度未能全部提高,湿强度却出现不同程度的下降。

Influence of lathe checks on microscopic mechanical properties of poplar veneer bonding interface and macroscopic shear strength was examined by using microscopic digital speckle pattern interferometry combined with macroscopic shear testing in this paper. In addition,gelatinized starch,gelatinized starch /wood flour compound,soybean adhesive were used to modify lathe checks of poplar bonding interface,and the relationship of microscopic strain distribution and macroscopic mechanical properties of modified samples was discussed. The results showed that the strain values of bonding interface with lathe checks were bigger at the value of 1. 5 × 10^-3- 4. 0 × 10^-3,and the whole composite strength decreased significantly. The strain values of bonding interface modified by different sealing treatment were remarkably bigger than unmodified samples,at the same time,not all dry shear strength increased while all wet shear strength deceased to varying degree.