低温环境下桦木顺纹抗压强度的研究  

Study on compression strength parallel to grain of birch wood at low temperature

作　　者：江京辉[1] 于争争 赵丽媛[1] 吕建雄[1] 赵有科[1] 

机构地区：[1]中国林业科学研究院木材工业研究所,北京100091 [2]北京林业大学材料科学与技术学院,北京100083

出　　处：《林业工程学报》2017年第4期30-33,共4页Journal of Forestry Engineering

基　　金：中央级公益性科研院所基本科研业务费专项资金项目(CAFINT2013C09)

摘　　要：为揭示不同水分状态木材在低温环境下的力学强度变化规律,研究了5种水分状态(饱水、生材、纤维饱和点、气干、绝干)桦木木材在0^-196℃低温环境下的顺纹抗压强度,并与室温环境下(20℃)的5种水分状态木材顺纹抗压强度进行比较。结果表明,在低温(0^-196℃)环境下,随着测试环境温度的降低,木材顺纹抗压强度增加,在-196℃环境下,5种水分状态的桦木顺纹抗压强度比室温环境下分别增加821.24%,718.05%,632.87%,223.75%和95.28%。木材顺纹抗压强度与温度呈线性关系,其斜率代表了顺纹抗压强度随温度变化的增加率,即木材含水率越高,随着低温温度的降低,顺纹抗压强度增速越大。在低温环境下,木材细胞中水分形成的冰柱,是木材顺纹抗压强度增加的主要原因。对绝干材而言,木材细胞壁上纤维和纤维胶着物质发生硬化,是其顺纹抗压强度增加的主要原因。The objective of this study was to investigate the effect of low temperature （- 196-0℃ ） on compressionstrength parallel to the grain （CSPG） of birch. The CSPG with five different moisture contents （MC） that were wa-ter-saturated, green, fiber-saturated, air-dried and oven-dried were analyzed from -196℃ to 0℃. The five moisturecontents were 136%, 67%, 29%, 12% and near to 0%. All specimens with a dimension of 20 （R） x20 （T） ~30（L） mm were cut from one piece of board. Seven temperatures were - 196℃ （ liquid nitrogen）, - 160℃, - 110℃,-70℃, -30℃, 0℃ and 20℃, being used in the experiments. The results showed that, when the temperature was be-low 0℃, the CSPG of specimen increased with the decreasing temperature. When the temperature decreased from20℃ to -196℃, the CSPG of the birch wood with five different moisture contents increased by 821.24%, 718.05%,632. 87%, 223.75% and 95.28%, respectively. The relationships between the CSPG and temperature could be de-scribed by a linear for the five MC levels of wood. The slope of the line increased with the increase of the MC, in oth-er words, the higher the MC, the faster increase in CSPG at the same low temperature. One of the primary reasonswas that the frozen ice in the wood cell walls and lumens increased the CSPG of wood at low temperatures. The MC ofthe oven dry wood was near to 0%. When the test temperature reduced, the fiber and fiber glue materials of wood cellhardening was the main reason for the increase of the CSPG.

关 键 词：低温环境 桦木 顺纹抗压强度 含水率 

分 类 号：TB35[一般工业技术—材料科学与工程]