Stress Wave Tomography Methods For Internal Defects In RL Plane Of Wood

Wood non-destructive testing technology which based on stress wave has important significance for the forest protection.The shape,size and position of the defect on the RL(radial and longitudinal)Plane of the wood cannot be obtained by conventional wood cross-sectional imaging.To overcome such limitations,this paper proposed two novel imaging method for the internal defects on the RL Plane of the wood.1、Based on the propagation law of the stress wave in the wood section we proposed a new method to distinguish the stress wave propagation path through the defect by using propagation velocity of stress wave on the RL plane of the wood.Secondly,the propagation velocity of the stress wave is converted into the value of the estimated point on the RL plane of wood and the two-dimensional imaging of the RL plane of wood is realized by using the velocity correction interpolation(VCI)method.2、This paper proposes a wood path-section defect imaging method based on path grouping interpolation method(GI).The grouping method is used to group the propagation paths of stress waves,and the stress wave path within the group is determined according to the velocity of stress wave.The defect path is marked with a special point,and the improved interpolation method is used to perform interpolation imaging of RL plane of wood.3、By using the stress wave non-destructive testing instrument,sample data were collected from the several different shapes of experimental samples,and the MFC was used to program the algorithm to realize the imaging of the path defects of the wood.The experimental results showed that VCI and GI method can reflect the defects of RL plane of wood better than the IDW method.The proposed method which can truly reflect the internal defects of the trees.Finally,the VCI、GI and IDW method are quantitatively analyzed using the method of confusion matrix.The results showed that the proposed method has higher average accuracy、average accuracy and average recall than IDW method,and the VCI method has better imaging results than other methods.