Time dependence of Poisson’s effect in wood III: asymmetry of three-dimensional viscoelastic compliance matrix of Japanese cypress
Time dependence of Poisson’s effect in wood III: asymmetry of three-dimensional viscoelastic compliance matrix of Japanese cypress
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DOI：
10.1007/s10086-013-1333-7
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发表时间：
2013-02
影响因子：
2.9
通讯作者：
K. Ando;Mayu Mizutani;Y. Taniguchi;Hiroyuki Yamamoto
中科院分区：
文献类型：
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作者：
K. Ando;Mayu Mizutani;Y. Taniguchi;Hiroyuki Yamamoto
为了从三维角度了解木材的粘弹性，在约9.7%的平衡含水量下，在纵向（L）、径向（R）和切向（T）方向上对日本柏树的匹配样品进行单轴拉伸蠕变加载。纵向和横向应变进行了测量的粘弹性泊松比和三维粘弹性的正常应变有关的顺应性张量的测定。在横向应变的变化表现出相同的趋势，在纵向应变，在所有方向的负载。也就是说，在蠕变过程中，横向应变的绝对值随着增加率的逐渐减小而继续增加;在去除载荷之后，它立即迅速恢复，之后它继续缓慢恢复。在蠕变过程中，横向应变最容易在T方向上增加，其次是R和L。所有的粘弹性泊松比和所有元素的粘弹性柔量的绝对值随蠕变时间的递增而递增。得出日本扁柏的三维粘弹性柔度矩阵是不对称的。
To understand the viscoelasticity of wood three dimensionally, matched samples of Japanese cypress were loaded in uniaxial tensile creep in the longitudinal (L), radial (R), and tangential (T) directions at approximately 9.7 % equilibrium moisture content. Longitudinal and transverse strains were measured for the determination of viscoelastic Poisson’s ratios and three-dimensional viscoelastic compliance tensors concerning the normal strain. The changes in the transverse strains showed the same tendencies as those in the longitudinal strains, in all directions of loading. That is, during creep, the absolute value of transverse strain continued to increase with the gradual reduction in the increase rate; immediately after the removal of the load, it recovered rapidly, after which it continued to recover slowly. The transverse strain increased most easily in the T direction, followed by R and L, during creep. All the viscoelastic Poisson’s ratios and the absolute values of all elements of the viscoelastic compliance increased logarithmically with creep time. The three-dimensional viscoelastic compliance matrix for Japanese cypress is concluded to be asymmetric.