Thermal behavior at wood and composite wood surfaces

当用白炽灯照射表面时，端面吸收的热量是边缘纹理表面的1.2倍。测定了不同颜色、不同密度的各种木材和不同密度的复合木材在白炽灯照射下的表面温升速率，模拟了人体皮肤与木材复合材料交界处的热行为。建立了基于有限差分数值方法的换热模型，分析了交界处温度和换热速率的变化。该模型可用于估计人的手掌与木材表面接触时的感官温度。利用针叶树种与周围组织的热物性差异，应用热学方法检测针叶树种的节结。用白炽灯照射木材表面，测量表面温度的变化率。结果表明，节间温升速率最低，其次为籽粒畸变区。从加热开始后60s的热图中可以检测到结点的大小，热是根据在缺陷部分的应力-应变曲线上建立的滞后环的能量损失产生的。反复弯曲的车辙图像可以检测出裂纹和某些缺陷。

The end surfaces absorbed 1.2 times more heat than did these of edge-grained surfaces when the surfaces are irradiated with incandescent lamps. The rate of surface temperature rise for various wood and composite wood with various colors and densities was determined when they were irradiated with incandescent lamps.Thermal behavior at a boundary between human skin and wood composites was simulated. The thermal transfer model based on numerical method with finite differences was proposed to analyze the changes in temperature and rate of heat transfer at the interfeaces. The model was valuable to estimate the sensory warmth felt by man's palm in conact with the wood surface.The thermogaphic method was applied to detect the knots, using with a difference in thermal properties of knot from the surrounding tissues for softwood species. The lumber surface was radiated with incandescent lamps and the rate of change in surface temperature was measured. As the results the rate of temprature rise was the lowest on the knot, follwed by distored grain region. From the thermograph at 60s after commencement of heating it has been found that the knot sizes could be detected.Heat is generated according to the energy loss of hysteresis loops which is obs erved at stress-strain curves of defect portions. Cracks and some kinds of defects could be detected by chermal images with repeated bending.