Mechanical properties of OSB via the five-point bending test

Interlaminar shear properties of wood composites are rarely evaluated because of the difficulty and cost of conducting established procedures set forth by the American Society of Testing and Materials (ASTM). A relatively new approach, known as the five-point method, was used to study the effects of span and width on shear-free Young’s moduli (E) and interlaminar shear moduli (G) and strength of oriented strandboard. The material evaluated was 23/32-inch (18-mm) grade-stamped single-layer-flooring with a 24-inch (610-mm) span rating. Specimen widths of 2, 6, and 10 inches (51, 152, and 254 m) were investigated over numerous spans in both the main and cross-panel directions. Combined ANOVA and multivariate regression techniques were applied to results of the elastic constants. Varying the pan had no effect on E with respect to the strong direction, but G in both directions and E in the cross direction slightly decreased as span decreased. At the 0.01 probability level, E in both directions increased significantly as width increased. Strength in both directions decreased rapidly as the span increased until a minimum level was reached; at this point, strength was relatively constant and independent of span. For the 6- and 10-inch (152- and 254-mm) widths, average strength in the main direction was 115 psi (793 kPa); 92 percent of the specimens were still failing in shear at the longest span investigated of 20 inches (508 mm). Comparison between five-point results and those of ASTM standards are also presented.

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