高温中胶合木构件胶缝界面剪切断裂能研究

Study on shear fracture energy for bondlines in glulam at high temperature

在氮气保护、温度为20~250℃条件下,开展了120个杨木、花旗松和落叶松-间苯二酚-酚醛树脂(PRF)胶缝界面剪切断裂能试验研究.结果表明:界面剪切断裂能随着温度的升高而降低;当温度为150℃时,由于PRF胶黏剂进一步固化,因此木材-胶黏剂胶缝界面性能提高;当温度高于150℃时,密度较低的杨木和花旗松-PRF胶缝界面断裂能试件的破坏位移下降明显,密度较高的落叶松-PRF胶缝界面断裂能试件的破坏位移相对稳定;20℃时杨木、花旗松和落叶松-PRF胶缝界面的剪切断裂能分别为4.68,5.05,5.37 N·mm-1,100℃时胶缝界面裂缝尖端塑性变形增加,剪切断裂能较初始值分别增加7.2%,6.6%和14.8%,250℃时界面剪切断裂能分别降至0.44,0.46,1.63 N·mm-1.

The study on interfacial shear fracture energy of 120 poplar, Douglas fir and larch-PRF(phenol-resorcinolformaldehyde)were conducted at 20~250 °C under nitrogen condition.Results show that the shear fracture energy of bondline presents a decline trend with the increase of temperature.The performance of wood-adhesive bondline is enhanced at 150 °C due to the further curing of PRF adhesive. The failure displacement of the poplar-PRF and Douglas fir-PRF bondline specimens with relatively low density for interfacial shear fracture energy testing decreases obviously when the temperature is higher than 150 °C,while the failure displacement of the larch-PRF bondline specimens with relatively high density for interfacial shear fracture energy testing is relatively stable.The shear fracture energies of poplar,Douglas fir and larch-PRF specimens are determined as 4.68,5.05 and 5.37 N?mm-1 at 20 °C,respectively.At 100 °C,the plastic deformation at the crack tip of the bondline increases,and the shear fracture energies increase by 7.2%,6.6% and 14.8% compared with the initial values,respectively.The interfacial shear fracture energies reduce to 0.44,0.46 and 1.63 N?mm-1 at 250 °C,respectively.