Modulus of Elasticity and Shear Deflection of Walnut-Veneered Particleboard Composite Beams in Flexure

A total of 150 specimens of three thicknesses (3/8, 1/2, and 3/4 inch) of particleboard, 3/4-inch walnut, and 1/36, 1/8, and 3/16-inch veneered-particleboard composites were tested under flexure with span-to-depth ratios of 24, 20, 16, 12, and 8. The variations of modulus of elasticity values were small among the three thicknesses of particleboard. Averaged value of modulus of elasticity for the particleboard was 529,000 psi, and for the walnut, 1,863,000 psi, all with a span-to-depth ratio of 24:1. A veneered particleboard with a shelling ratio of 0.333 or 1/8-inch veneered 1/2-inch particleboard (3/4 inch total thickness) under a static bending test had a modulus of elasticity value of 85 percent to that of the 3/4-inch solid walnut. The pure modulus of elasticity value derived from bending tests for both face walnut and particleboard was approximately 12 percent greater than that of the experimental modulus of elasticity value tested at a span-to-depth ratio of 24:1. Deflection due to shear reached 15.0, 19.7, 31.4, and 37.8 percent of the total deflection at shelling ratios of 0.000, 0.074, 0.333, and 0.500, respectively, for the particleboard; 1/36,1/8, and 3/16-inch veneered particleboard in static bending at a span-to-depth ratio of 24:1. The maximum shear deflections reached 60.0, 69.0, 80.5, and 90.0 percent of the total deflection at shelling ratios of 0.000, 0.074, 0.333, and 0.500, respectively, for plain particleboard and veneered composites, all with a span-to-depth ratio of 8:1. It showed that the shear deflection increases with the increase of the shelling ratio or veneer thickness of the veneered-particleboard composite at all span-to-depth ratios tested. The shear deflection also increased with decreasing span-to-depth ratio. It was found that Equation [2] was especially accurate for approximating the total bending deflection for the 1/36-inch veneer-faced particleboard with 3/4-inch thick particleboard core.

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