Analysis of acoustic velocity as a predictor of stiffness and strength in 5-inch-diameter pine dowels

In an effort to optimize merchandizing and conversion of small-diameter trees, nondestructive assessment of mechanical properties may improve utilization and resultant product properties. This research tested the ability of acoustic velocity to predict bending stiffness and strength in 5-inch-diameter southern pine dowels. For nondestructive testing, a handheld receiver/computer was employed and used in conjunction with a 1.5-pound hammer (impactor). Acoustic velocity was measured in both green and dry dowels. Following drying and nondestructive testing, the dowels were destructively tested in bending under centerpoint loading. The best single-predictor correlation was observed between acoustic velocity (green) and stiffness (r2 = 0.66), while correlation was poor for acoustic velocity (green) and strength (r2 = 0.18). In each case, acoustic velocity (dry) was a less effective single predictor. Also in each case, the addition of the number of growth rings per inch as a predictor improved the regression model.