Mechanical Characterization of Lumber of Small-Diameter Hardwood Species after Different Drying Schedules

Abstract

The influence on the drying behavior as well as the mechanical properties of lumber of small-diameter hardwoods at different low-temperature convection kiln dryings was investigated. Standard test methods in three-point-bending and the modulus of elasticity in three-point-bending, compression tests parallel and perpendicular to the grain, as well as Brinell hardness tests were performed in order to assess the drying quality. Furthermore, non-standard tensile tests perpendicular to the grain and fracture energy tests in radial/longitudinal and also in tangential/longitudinal crack propagation systems were carried out as a most sensitive test method. The results showed significant changes of the specific fracture energy, bending strength, compression strength parallel and perpendicular to the grain, and the Brinell hardness with good drying performance at the same time.

Keywords:

• Kiln drying
• Lumber of small-diameter hardwood
• Mechanical properties
• Specific fracture energy

Notes

1. Conservative drying.

2. Accelerated drying.

*According to the Austrian timber grade practice.^{[ 10 ]}

MC. Moisture content; EMC. Equilibrium moisture content; ac. Automatic control.

A. Oak; B. Beech; C. Ash; D. Sycamore.

1. Conservative drying; 2. Standard drying; 3. Accelerated drying.

Framed boxes show significant differences (p < 0.05) between conservative and accelerated drying schdules.