文献类型：期刊文献

英文题名：Comparative investigation on the orthotropic viscoelastic properties of wood during cooling and heating variations

作者：Li, Zhu[1] Jiang, Jiali[1] Lyu, Jianxiong[1] Cao, Jinzhen[2]

第一作者：李珠

通信作者：Lyu, JX[1]

机构：[1]Chinese Acad Forestry, Res Inst Wood Ind, Hunan Collaborat Innovat Ctr Effect Utilizing Woo, Beijing 100091, Peoples R China;[2]Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing, Peoples R China

年份：0

外文期刊名：WOOD MATERIAL SCIENCE & ENGINEERING

收录：;EI(收录号：20215211406399);Scopus(收录号：2-s2.0-85121832740);WOS:【SCI-EXPANDED(收录号:WOS:000734313900001)】；

基金：The authors are grateful for the financial support from the National Natural Science Foundation of China [grant numbers 32071689 and 31971591].

语种：英文

外文关键词：Chinese fir; orthotropic viscoelasticity; cooling and heating variations; moisture content; low temperature

摘要：Differences in the orthotropic viscoelastic properties of Chinese fir wood (Cunninghamia lanceolata) during cooling and heating variations were investigated in the temperature range between -120 degrees C and 25 degrees C. The stiffness and damping of the longitudinal (L), radial (R), and tangential (T) specimens were determined for five equilibrium moisture content (EMC) levels ranging from 0.6% to 25.2%. Results showed that the tensile storage modulus (E') values in the cooling run were lower than those in the heating run at each temperature, regardless of the grain orientation and EMC level. The absolute value of the changing rate of E' (vertical bar Delta E'vertical bar) in the cooling run was more pronounced than that in the heating run. The values of vertical bar Delta E'vertical bar demonstrated an anisotropy at all EMC levels, while the vertical bar Delta E'vertical bar of L specimens were lower than that of transverse specimens. Compared to per unit temperature, per unit moisture content exerted more influence on the stiffness of specimens. The gamma-relaxation was observed in the loss modulus (E '') and loss factor (tan delta) temperature spectrum. The gamma-relaxation peak temperature in the E '' temperature spectrum was lower than that in the tan delta spectrum. The gamma-relaxation peak temperature in the cooling run was lower than that in the heating run, irrespective of the grain orientation. Furthermore, the gamma-relaxation peak temperature shifted to a lower temperature range with an increasing amount of adsorbed water, independent of cooling and heating runs.