中文摘要：

研究应力波在立木内部纵截面上的传播规律及影响因素,建立传播速度模型。以浙江农林大学植物园内4个树种共计40株树木作为实验样本,采用Arbor Sonic 3D应力波成像系统测量应力波在不同角度纵截面上各点间的传播速度。结果表明：同一截面上任意2点间的传播速度随方向角的增大而增大;不同纵截面上任意2点间的传播速度与所在纵截面与径切面的夹角相关。对健康样本试验数据的拟合结果为v（θ,α）/v0≈kx2＋1（0≤k≤1）,k值取决于被测树木的物理力学参数;所有建立的回归模型决定系数R2均大于0.93,表明具有较高的拟合优度。不同树种应力波速度各不相同。纵截面上应力波传播规律与方向角θ和α相关,θ决定速度大小,α决定速度变化,即决定拟合方程二次项系数k的大小。健康树木纵截面上θ,α和v（θ,α）/v0满足如下关系：f（θ,α）=1＋{[vl-（-0.2α2＋1）vR]/vl}·θ2。对不同树种的检测结果均表明了该模型的有效性,在木材无损检测方向具有重要实际应用价值。

英文摘要：

To establish a propagation velocity model of stress wave in longitudinal section,standing trees of different species were selected as samples to study their stress wave velocity pattern for different angles in the longitudinal section of wood.Using a theoretical analysis,the velocity model of stress waves in the longitudinal section of wood was built.Then within the Zhejiang A F University Botanical Gardens,a total of 40 test samples from four species of trees was selected.The experimental Arbor Sonic 3D stress wave imaging system was used with a comparative analysis of the results to determine the stress wave propagation velocity.Analysis of the model included fitting an equation to a healthy sample and a regression analysis.Results showed that the propagation velocity between any two points in the same section increases with increasing direction angle.And the propagation velocity between any two points in different longitudinal sections is related to the angle between the longitudinal section and the diameter section.Healthy sample test data were fitted to：v（θ,α）/v0≈ kx2＋ 1（0 ≤ k ≤ 1） where k was dependent on the size of angle α between the longitudinal section and the radial section of the tree under test.In the established regression model the R2 0.93 indicated that the model had a high goodness of fit.For different species,due to different internal characteristics,stress wave velocities also differed.The propagation law of stress wave in longitudinal section is related to the direction angle θ and α.θdetermines the velocity,and α determines the velocity change,which means the size of the quadratic coefficient k of the fitting equation.For the longitudinal section of healthy trees,θ and α and v（θ,α）/v0 satisfied the geometric relationships：f（θ,α）=1＋{[vl-（-0.2α2＋ 1）vR]/vl}·θ2.Overall,detection results of different species showed the validity of the model which could have important practical applications for nondestructive testing of wood.