Modeling Mechanical Properties of 2 by 4 and 2 by 6 Southern Pine Lumber Using Longitudinal Vibration and Visual Characteristics

The light-frame building construction market is increasingly competitive. To maintain and grow its position in the market, the lumber industry needs to be improved and refined. The identification of the strength-reducing characteristics that affect modulus of elasticity (MOE) and modulus of rupture (MOR) are keys to improve the grading process of lumber. Herein, nondestructive techniques, visual evaluation, and mechanical testing were used to assess the structural properties of 1,044 samples of southern pine lumber. Linear regression models were constructed for 2 by 4 and 2 by 6 southern pine lumber using the static bending MOE and MOR, both as dependent variables from the destructive test. Nondestructive measurements, visual characteristics, and lumber density were used as independent variables. Linear regression models were constructed to indirectly estimate the MOE and MOR of southern pine lumber. The variables selected to predict MOE were dynamic modulus of elasticity (dMOE) and density. By adding knot diameter ratio to dMOE and density, it was possible to develop a prediction model for MOR. It was possible to improve predictability of strength (MOR) with a combination of nondestructive testing and knot evaluation.