Research engineer, Forest Products Laboratory, USDA,
Compressive and tensile strength of dry Douglas-fir was measured through rapid constant deformation rate tests at temperatures from 25 to 288°C, at initial thermoequilibrium and after 2 h of heating.
The tensile strength decreased slowly with increasing temperatures to 175°C. Above 175°C, the tensile strength reduces rapidly. This is attributed to alteration of the cellulosic fraction of wood.
The compressive strength decreases more uniformly with temperatures increasing to 288°C due to changes occurring in all three basic wood components with change in temperature.
A first-order reaction equation for bond rupture/formation was adopted to describe the response. Including only terms for bond rupture resulted in good correlation to the observed strength response at reaching thermoequilibrium.
Paper ID: JTE10025J