木材乾燥に適応可能な新規レオロジーモデルの開発

在测定杉木和日木箱心材表面和内层的粘弹性蠕变性能之后，采用悬臂蠕变试验方法测定木材表面和内层在20、65、80和90℃温度下的力学吸附蠕变性能。在20°C和65°C的温度下，施加其断裂载荷20%的载荷进行蠕变试验。在温度为80°C和95°C的蠕变试验中，在悬臂梁的自由端施加其断裂载荷的10%的载荷。应变片在试样的上、下两面按第四个跨度粘接。在温湿度室中，测量了试件在荷载和相对湿度（RH）循环变化作用下的挠度和应变。力学吸附蠕变定义为累积含水率变化的函数，并采用由一个开尔文单位和一个阻尼器串联组成的模型来确定木材的力学吸附蠕变特性。从蠕变试验结果来看，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度均有增大的趋势。此外，在第一个RH循环时，试件的挠度和蠕变速率最大。实验数据与模型拟合结果吻合较好。因此，本研究获得的模型参数可用于木材力学-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.