RELATIONSHIP BETWEEN LOG AND LUMBER MODULUS OF ELASTICITY

Past nondestructive evaluation (NDE) research efforts have paved the w ay for the successful use of NDE for determining the quality of finish ed wood products. However, little effort has been expended on developi ng nonvisual NDE techniques for use in grading or sorting logs for int ernal soundness and structural quality. This paper describes the resul ts of a study that addressed this problem. Longitudinal stress wave ND E techniques were used to evaluate the quality of 193 balsam fir and e astern spruce logs prior to processing into lumber. Longitudinal speed -of-stress wave transmission was used to determine the modulus of elas ticity (MOE) for each log. The MOE of each piece of structural lumber cut from the logs was then determined using transverse vibration NDE t echniques. A strong relationship was observed between the MOE of the l ogs and the lumber obtained from the logs.