Prediction of Internal Defect Area in Wooden Components by Stress Wave Velocity Analysis

Xin Li, Jian Dai, Wei Qian, Li-Hong Chang

Abstract


In this study, wooden components torn down from ancient buildings were used as the experimental materials. With methodology based on reverse simulation testing, some artificial holes making up different proportional areas of their cross-section were chiseled and tested with a six-sensor-point stress wave testing device. The results indicated that two-dimensional analog images could be used to judge the internal defects of wooden components qualitatively but did not provide quantitative, accurate determination. By comparing and contrasting the attenuation tendency of stress wave velocities among adjacent sensor points, separated sensor points, and diagonal sensor points, the defect grade of wooden components can be classified. Six variations were chosen as discriminant factors. These were the attenuation coefficients of the stress wave velocities via three propagation paths and the relative proportions of their absolute values. The Mahalanobis distance discrimination model was adopted for the in-grade estimation of the internal defects present in the component’s cross-section. This method had high operability and no misjudgment ratio.

Keywords


Ancient buildings; Wooden components; Stress wave; Internal defects; Distance discrimination

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