木材乾燥に適応可能な新規レオロジーモデルの開発

在测定了Sugi和Hinoki箱心木材表层和内层的粘弹性蠕变性能后，用悬臂蠕变试验测定了木材表层和内层在20、65、80和90℃下的机械吸附蠕变性能。在20℃和65℃下进行蠕变试验，在80℃和95℃下进行蠕变试验，在悬臂梁的自由端施加断裂载荷的10%。应变片在试件的上表面和下表面的第四个跨度被粘接。在温湿室中测量了36h载荷和循环变化相对湿度(RH)下试件的挠度和应变，将机械吸附蠕变定义为累积含水率变化的函数，并用一个开尔文单元和一个串联的仪表盘组成的模型来确定木材的机械吸附蠕变特性。从蠕变试验结果可以看出，温度对木材的蠕变性能有显著影响。随着温度的升高，木材表层和内层试件的蠕变柔量有增大的趋势。此外，在第一个RH循环中，观察到试件的最大挠度和蠕变速率。实验数据与本研究中使用的模型进行了拟合，结果表明吻合较好。因此，本研究得到的模型参数适用于木材机械吸附蠕变特性的识别。

Following determination of viscoelastic creep properties of surface and inner layer of Sugi and Hinoki boxed-heart timber, determination of mechano-sorptive creep properties of surface and inner layer of the timbers was then conducted at temperature of 20, 65, 80 and 90°C using cantilever creep test. A load of 20% from its rupture load was applied for the creep test at temperature of 20 and 65°C. In case of the creep test at temperature of 80 and 95°C, a load of 10% from its rupture load was applied at the free-end of the cantilever. Strain gauges was bonded at a fourth span on upper and bottom faces of the specimen. Deflection and strain were measured on the specimen subjected to load and cycling change of relative humidity (RH) in a temperature and humidity chamber for 36 h. Mechano-sorptive creep is defined as a function of cumulative moisture content change and a model consisted of one Kelvin unit and one dashpot connected in a series was used to determined mechano-sorptive creep properties of the timber. From the creep test results, it was found that temperature had significant effects on the creep properties of the timber. The creep compliance of surface and inner layer specimen of the timbers tended to increase as temperature increased. In addition, the largest deflection and creep rate of the specimen was observed at the first RH cycle. Fitting experimental data with model used in this research shows a good agreement. Therefore, model parameters obtained in this research were applicable for identification of mechano-sorptive creep properties of the timber.