宽温度域水分增塑木材的黏弹性与时湿等效

It is difficult to control specimen’s moisture content during the experiment of wood viscoelasticity under high temperature, so no one has ever studied wood viscoelasticity systematically under high temperature. This project is to study viscoelasticity of water plasticized wood systematically with advanced equipment under wide temperature field, and to bring up and discuss new theory: time-moisture superposition, so that it enriches the viscoelastic theory of wood，contribute to construct mechanic system of wood viscoelasticity and provides guidance for wood drying, wood-based panel pressing, wood structure design, etc.. We systematically test and analysis creep and stress relaxation of specimen coated with high temperature film under wide temperature field and wide moisture content field, using DMA with humidity accessory manufactured in USA. The thesis published by the applicant indicates that moisture change of specimen ( moisture content: 12%, temperature: 95℃)can be controlled within 0.2% during experiment. We also will do research on simulation of fitting, time-temperature superposition, etc.; based on which, we will bring up and discuss time-moisture superposition, and deduce the equation of displacement for TMSP, and based on the quantitative relation of coupling effect of temperature and moisture content, we will discuss time-temperature-moisture superposition more deeply and deduce its dual equation of displacement.. Key words: wood viscoelasticity, creep, moisture content, time-temperature superposition, time-moisture superposition

高温条件下木材黏弹性试验过程中很难控制住试件的含水率，因而迄今无人研究过木材高温条件下的黏弹性。本项目旨在用先进的设备，系统地研究宽温度域内水分增塑木材的黏弹性，并提出和探讨新的理论-时湿等效性。本研究将丰富木材的黏弹性理论，有助于木材黏弹性力学体系的构建；为木材干燥、人造板热压、木结构设计等提供有力的理论指导。.本研究采用带湿度附件的美国产DMA加试件包耐高温膜的方法（申请人已发表的SCI论文表明，含水率12%试件95℃试验过程中含水率的变化能控制在±0.2% 内 ），系统地测定宽温度域和宽含水率域内木材的蠕变和应力松弛，分析其变化规律，并进行模型拟合、时温等效等研究；在此基础上提出和探讨时湿等效性，推导时湿等效位移方程，并基于试验中测定到的温度和含水率耦合效应的定量关系进一步探讨时间-温度-湿含量的等效性，推导其双重位移方程。.关键词：木材黏弹性；蠕变；含水率；时温等效；时湿等效

高温条件下木材黏弹性试验过程中很难控制住试件的含水率，因而迄今无人系统地研究过木材在宽温度域和宽含水率域条件下的黏弹性。本研究将丰富木材的黏弹性理论，有助于木材黏弹性力学体系的构建；并对木材干燥、人造板热压、木结构设计等提供有力的理论指导。. 本研究采用带湿度附件的美国产DMA加试件包耐高温膜的方法，系统地研究了温度0-95℃和含水率0-24%木材黏弹性。试验过程中精确控制了木材含水率，含水率12%试件在95℃试验过程中含水率的变化能控制在±0.2%内。. 试件的总柔量、瞬时柔量和蠕变柔量均随温度升高而增大，初始松弛模量和终了松弛模量均随温度升高而减小。低含水率试件受温度的影响较小，而高含水率试件的受温度的影响很大，两者存在着数量级的差距。在一定的温度下，蠕变柔量和松弛模量会出现突变。. 试件含水率对总柔量、瞬时柔量、蠕变柔量和松弛模量都有很大影响。总柔量、瞬时柔量随含水率的增大而显著增大，初始松弛模量和终了松弛模量随含水率的增大而减小。. 无论试件的纹理方向为顺纹或横纹，温度与时间对蠕变和应力松弛的影响存在等效性，且主曲线和位移因子均会受到木材含水率和参考温度的影响；同样地，含水率与时间对蠕变和应力松弛的影响存在等效性，且主曲线和位移因子均会受到温度和参考含水率的影响。