汽蒸预处理白栎木材弯曲蠕变的时温等效特性  

Time-temperature equivalence in bending creep of white oak wood in steam pretreatment

作　　者：张毓格 侯俊峰[1] 岑俊杰 章卫钢[1] 姜志宏[1] 俞友明[1] ZHANG Yuge;HOU Junfeng;CEN Junjie;ZHANG Weigang;JIANG Zhihong;YU Youming(College of Chemistry and Materials Engineering,Zhejiang A&F University,Hangzhou 311300,Zhejiang,China)

机构地区：[1]浙江农林大学化学与材料工程学院,浙江杭州311300

出　　处：《浙江农林大学学报》2023年第5期1121-1129,共9页Journal of Zhejiang A&F University

基　　金：国家自然科学基金资助项目(32201492,31670561);浙江农林大学科研发展基金人才启动项目(2020FR020)。

摘　　要：【目的】在采用MATLAB2019a软件对早材导管带特征进行数字化表征的基础上,探究汽蒸预处理和早材导管带对白栎Quercus alba木材弯曲蠕变的时温等效特性影响规律。【方法】采用饱和蒸汽(100℃)及过热蒸汽(110、120℃)对试样进行预处理,利用动态热机械分析仪(DMA-Q800)在不同测试温度(20~80℃)条件下测试试样的弯曲蠕变曲线,最后选用测试温度20℃探究试样弯曲蠕变的时温等效特性,并运用Williams-Landel-Ferry(WLF)方程对水平移动因子与测试温度的关系曲线进行拟合。【结果】①试样的瞬时应变和恒定载荷5MPa保持的45min应变均随测试温度的升高而增大。然而,试样的瞬时应变和45 min应变均随汽蒸预处理温度的升高而减小。②基于时温等效原理,可将不同汽蒸预处理试样45 min的短期蠕变曲线平移得到测试温度20℃下白栎木材的长期蠕变曲线。试样的水平移动因子与测试温度的关系曲线满足WLF方程,回归系数(R^(2))均大于0.93,用WLF方程可以对蠕变特性的时间与测试温度关系进行有效表达。【结论】汽蒸预处理、测试温度和早材导管带对白栎木材的弯曲蠕变性能均影响显著;在20~80℃测试温度范围和汽蒸预处理温度(100~120℃)范围内,时温等效适用于白栎木材的弯曲蠕变。[Objective]This study,with the employment of MATLAB 2019a software,is aimed to complete the time-temperature equivalence in bending creep of white oak in steam pretreatment on the basis of digital characterization of earlywood vessel belt characteristics.[Method]First,an investigation was carried out of the creep behavior of specimens pretreated by steam at 100,110,120℃using a dynamic thermo-mechanical analyzer(DMA-Q800)at the test temperature ranging from 20 to 80℃.Then,time-temperature equivalence was applied to predict the long-term creep behavior of white oak on the basis of 45 min creep curves of tested specimens.At last,a further analysis was conducted of the relationship between horizontal shift factor and temperature in accordance with Williams-Landel-Ferry(WLF)equation.[Result](1)Instantaneous strain and 45 min strain under the permanent load of 5 MPa for tested specimens increased with the rise of test temperature yet the strain of specimens decreased with the increase of steam treatment temperature.(2)The 45 min creep curves of specimens can be processed to obtained the long-term creep curves at the referenced test temperature of 20 ℃ according to time-temperature equivalent. (3) The curves between horizontal shift factor and temperature of specimens met the requirements of WLF equation with R^(2) greater than 0.93. (4) The WLF equation can effectively describe the relationship of creep characteristics between test time and temperature. [Conclusion] Steam pretreatment, test temperature and earlywood vessel belt affected the creep behavior of white oak wood significantly and it is feasible to predict the long-term creep behavior of white oak wood by WLF equation in test temperature of 20−80 ℃ and steam pretreatment temperature ranging from 100 to 120 ℃.

关 键 词：白栎木材 弯曲蠕变 汽蒸预处理 早材导管带 时温等效 

分 类 号：S781.3[农业科学—木材科学与技术]