Product and Process Variables Associated with a Shaped Particle Beam

Several forming methods were tried in constructing 9-1/4-inch by 8-foot I-beams of reconstituted wood particles using shaped molds and standard particleboard pressing techniques. The forming method holding most promise for commercial application maintains a level mat during the forming period by utilizing a low bulk density fiberous material for the web portion of the beam and alined flakes with high bulk density for the flange areas. Beams having bending stiffness, EI of 1.8 by 106 psi and breaking loads of 10,750 pounds were constructed using alined 0.020- by 0.5- by 2-inch disk flakes in the flanges and 0.020-by 2-inch ring flakes randomly dispersed in the web. Bending stiffness was comparable to that of a solid lumber beam of equal weight while strength was only half that of a lumber beam. In all, twelve beams were constructed using different type, location, and alinement of particles. Beams which were assembled with different material in each flange showed a reduction in bending stiffness and bending strength from those beams having a balanced construction. Gradually changing from flange to web material through a transition zone is a suggested means of reducing stress concentration in the beams. Short span versus long span deflection measurements showed horizontal shear stiffness to be a significant factor in beam design. With proper engineering design and good forming techniques, beams could be made of reconstituted particles to suit a variety of structural applications.

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