The effects of yield stress of poplar (Poplar × euramericana cv. ‘Neva’) on temperature (60–210°C), moisture content (oven dry-30%) and grain response mechanism and as well as its role in the formation of sandwich compressed wood were studied in this paper. The results showed that the yield stress of wood was significantly affected by moisture content(MC), temperature and their interaction. Compared with temperature, the relative change rate of yield stress was nearly 10 times higher for each 1% increase in MC than for each 1°C increase in temperature. The experimental data revealed that the relative change rate of yield stress depended on the softening effect of wood by moisture and temperature. The asymmetry of yield stress in different grain direction also depended on wood hydrothermal softening effect. Raising the temperature or increasing the MC could make wood radial vs tangential asymmetry decrease and radial vs radial tangential asymmetry disappear. In the process of hydrothermal compression, the yield stress gradient caused by the hydrothermal softening inside the wood was the main reason for the formation of sandwich compressed wood, and provided a scientific basis for the controllability of the position and thickness of the compressed layer(s).

杨树屈服应力的影响（白杨 × 欧美黑简历。本文研究了温度（60–210°C），水分（烤箱干燥-30％），谷物响应机理及其在夹心压缩木形成中的作用等方面的“ Neva”。结果表明，木材的屈服应力受含水量，温度及其相互作用的影响很大。与温度相比，MC每增加1％，屈服应力的相对变化率要比温度每升高1°C高近10倍。实验数据表明，屈服应力的相对变化率取决于木材受水分和温度的软化作用。木材不同方向的屈服应力的不对称性也取决于木材的水热软化效果。升高温度或增加MC可以使木材的径向与切向不对称性降低，径向与径向切向不对称性消失。在水热压缩过程中，木材内部水热软化引起的屈服应力梯度是形成夹心压缩木的主要原因，为压缩层位置和厚度的可控性提供了科学依据。 ）。