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为进一步探讨木材在高温高压蒸汽干燥过程中的应力释放机理,该研究以日本柳杉木材为研究对象,利用新开发的耐热、耐压应力传感器和专用夹具,对高温高压蒸汽条件下木材的拉伸应力松弛特性进行了较为详细、全面的系统研究.结果表明:温度条件对木材应力松弛的影响远比应变水平的影响显著,随着温度的增加、木材应力松弛急剧增大,残余应力迅速下降;木材应力的松弛除了受温度的影响外,受环境相对湿度的影响显著.无论木材的径向还是弦向,其拉伸应力松弛过程中的残余应力和木材干燥过程中的最大收缩应力随温度变化的关系十分吻合.该结果充分证明了木材在高温高压过热蒸汽干燥过程中的收缩应力显著降低,是由于收缩变形而引起的收缩应力在长时间处于拉伸状态下应力释放所致.
In order to further investigate the stress release mechanism of wood in the process of high temperature and high pressure steam drying, the research took the Japanese cedar wood as the research object, and made use of newly developed heat-resistant and pressure-resistant stress sensors and special fixtures. The results show that the influence of temperature on the stress relaxation of wood is far more significant than that of strain level. With the increase of temperature, the stress relaxation of wood increases sharply, and the residual stress rapidly increases. Except for the influence of temperature on the relaxation of wood stress, which is significantly affected by the relative humidity of the environment.Whether the radial or chord direction of wood, the residual stress in the process of tensile stress relaxation and the maximum shrinkage stress in the process of wood drying The results are consistent with the temperature of the results show that the wood in the high temperature and pressure superheated steam drying shrinkage stress was significantly reduced due to shrinkage deformation caused by shrinkage stress in a long time in the tensile stress relief.