The Flexural Properties of Eastern Oak Pallet Lumber

Bending properties of cut-to-size pallet lumber are a critical input in the design of wood pallets. Because of the size and importance of the pallet industry, these properties can have a major impact on the performance and reliability of America’s materials handling systems. Over 2,700 samples of green eastern oak deckboards (1 by 4, 1 by 6) and stringers (2 by 4) were randomly sampled from mills located throughout the Eastern United States. Each piece was graded according to National Wooden Pallet and Container Association specifications and tested to destruction in third-point bending. The results showed that there were statistically, but not practically, significant differences between red and white species groups and between 1 by 4 and 1 by 6 deckboards. Coefficients of variation (COV) for modulus of elasticity (MOE) and modulus of rupture (MOR) ranged from 22.6 and 29.7 percent and 18.9 to 29.3 percent, respectively, for individual grades of stringers and deckboards. Average deck-board and stringer MORs for all sampled lumber were nearly equal and averaged 7,174 pounds per square inch (psi) indicating that any effect of size was eclisped by others factors. Stringer MOE averaged 1.182 x 106 psi with deckboard MOE 12 percent greater. The grading procedure did significantly segregate material by strength and stiffness. The populations of lumber MOR and MOE were characterized by Weibull and Gaussean distributions for use in computer simulation of pallet performance and development of reliability-based design procedures for wood pallets.

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