Viscoelasticity of Air-Dried or Thermo-Treated Woods

Evaluation of Viscous-Elastic Properties of Resonance Maple Wood

“…The results obtained by [2; 13; 18] show that softening of softwood actually takes place at higher temperatures than for hardwood. Another aspect is also important for interpretation: wood tissue is more regular in the radial direction compared to the tangential direction [16][17]. In bending tests (the load applied in the radial direction produces a bending moment in the tangential direction), the cell walls are loaded mainly with pure traction and compression, while if the load is applied in the tangential direction producing a bending moment in the radial direction, cell walls are rather exposed to bending, behaviour described by [17].…”

“…Another aspect is also important for interpretation: wood tissue is more regular in the radial direction compared to the tangential direction [16][17]. In bending tests (the load applied in the radial direction produces a bending moment in the tangential direction), the cell walls are loaded mainly with pure traction and compression, while if the load is applied in the tangential direction producing a bending moment in the radial direction, cell walls are rather exposed to bending, behaviour described by [17]. The tangential stress due to simple plane bending induces a cellular slip that most likely occurs in the middle lamella.…”

Effect of surface carbonization on mechanical properties of LVL

“…The failure mode was not changed as the temperatures increased; for example, crack failures were seen in the surface layers of the samples that were heated at 120 °C, and 240 °C, and not in the others. The elasticity of heat-treated wood might increase because of additional lignin cross-linking near the glass transition temperature (Villani et al 2017), which could be the reason why a crack failure was not found in Sample Ⅲ or Sample Ⅳ. The carbonized surface layers had a complicated effect on the LVL, which was not homogeneously made.…”

“…The integrity of fiber failure was seen in all five samples without stratification caused by different layers, except for a crack failure in the face veneer of Sample Ⅱ.The failure mode was not changed as the temperatures increased; for example, crack failures were seen in the surface layers of the samples that were heated at 120 °C, and 240 °C, and not in the others. The elasticity of heat-treated wood might increase because of additional lignin cross-linking near the glass transition temperature(Villani et al 2017), which could be the reason why a crack failure was not found in Sample Ⅲ or Sample Ⅳ.…”