Performance of timber board models for prediction of local bending stiffness and strength - with application on Douglas fir sawn timber

Efficient utilization of structural timber requires accurate methods for machine strength grading. One the most presented this far is based on data local fiber orientation board surfaces, obtained from laser scanning. In paper, two potential improvements method are examined. The first one consists replacing a model simple integration over cross sections boards calculation bending stiffness by 3D solid finite element (FE) which derived. second improvement concerns replacement in interior more advanced taking location pith and growth direction knots into account. Application alternative models sample than 200 Douglas fir boards, size 40 mm X 100 3000 mm, cut large logs, show that each evaluated contributes to improved grading accuracy. When calculated utilizing herein suggested FE combination with coefficient determination as high 0.76 obtained. For comparison, 0.71 obtain using simpler original models.