Shelling Ratio and Core Density Effects on Stiffness, Ultimate Strength, and Toughness of Veneered-Hardwood Beams

Static bending tests were conducted on 3/4-inch-thick, 12-by 39-inch hardboards, red oak veneered-hardboard composites, and red oak lumber. Toughness tests were made on small specimens (3/4 square by 11 in.) using a (USDA Forest Service) toughness testing machine. Both MOE and MOR values of hardboard cores increased with increasing density regardless of the thickness. Values of MOE, MOR, and toughness were influenced by shelling ratio and hardboard core density of the composite specimens with shelling ratio exhibiting a greater effect. Shelling ratio is defined as the ratio of the total face thickness to the total thickness of the composite panel. At shelling ratios of 0.262 and greater, the stiffness of the panels approached that of red oak lumber; values of the ultimate bending strength and toughness of the panel were equal to or superior to those of the commercial red oak plywood. As functions of shelling ratio or red oak veneer thickness, hardboard core density, and their interaction, all values of the dependent variables of MOE, MOR, and toughness could be described by three multivariable least squares regression equations. The interaction of shelling ratio and core density affected MOE and toughness but not MOR.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member