Mechanical behaviour of wood compressed in radial direction: Part II. Influence of temperature and moisture content

Abstract

This study investigated the influence of pressing temperature and moisture content on the mechanical properties of wood compressed in radial direction. Jack pine (Pinus banksiana) and balsam poplar (Populus balsamifera) specimens were tested under a combination of pressing temperature (20 °C, 55 °C, 90 °C, and 125 °C) and wood moisture content (2%, 7%, 12%, and 17%). The yield stress (σy) and modulus of elasticity (MOE) of the specimens were determined from the stress- strain response. It was found that an increase in either pressing temperature or moisture content of wood generally caused a decrease in the mechanical properties for both species. The t-test results revealed that jack pine specimens are more sensitive to changes in pressing temperature and wood moisture content than balsam poplar. For jack pine specimens, at any of the pressing temperatures, the moisture content of 12% was found to be a crucial level to start a significant decrease in σy and MOE, while at any of the moisture content, a change in temperature from 55 °C to 90 °C exhibited a significant change in σy and MOE. The regression models developed can be used to predict σy and MOE as a function of temperature and moisture content.

Keywords

• Compression in radial direction
• Yield stress
• Modulus of elasticity
• Pressing temperature
• Wood moisture content
• Stress-strain curve