Study On The Log Heartwood And Sapwood Density And Moisture Content Detection Based On Computed Tomography

Under the current circumstances of forest resources scarcity and the highly consumption of timber, using computed tomography (CT) technology for nondestructive testing of log density and moisture content before sawing, is of great significance to timber saving and reasonable selecting. In this paper, CT technology was applied for forecasting density and moisture content of the logs of two ages, heartwood and sapwood respectively. It proved that CT was a feasible way to forecast density and moisture content for the different ages, heartwood and sapwood of logs, through establishing the prediction models of CT number-density, CT number-moisture content.Two ages of Fraxinus mandschurica, Ulmus pumila L., Larixgmelinii and Pinus tabudaeformis var.mukdensis Uyeki which were common in north, were selected for studying the influence of different tree ages and wood types on CT detection. After sawed and marked, the samples of two ages, heartwood and sapwood of logs were scanned by CT scanner. The samples were divided into two groups; one was for validation, the other for experiment. The average CT number of each sample was calculated.Drainage method was used to measure the density of samples. The prediction models of CT number and density of logs’two ages, heartwood and sapwood were established, through matching samples’CT numbers and density values. The results were linear relationships and CT numbers had the positive correlation with density values. Weighing method was applied for moisture content measurement. The relationships between CT numbers and moisture content values were linear, and CT numbers had the negative correlation with the moisture content values. The CT numbers of control group were put into the linear formulas and the predicted values of density and moisture content were got. The calibration curves were got by comparing predicted values and measured values. The correlation coefficients (R2) were above0.84which showed the prediction results were in conformity with the measurement results.The linear relationships between CT numbers and density values, CT numbers and moisture content values were established for heartwood and sapwood of two ages of logs. The results illustrated that CT could be used for density and moisture content measurement regardless of logs’different ages and parts. Thus a new method for density and moisture content measurement was found.