Creep parameters of spruce wood in high temperature environment

Abstract

The paper presents partial results of an ongoing project dealing with thermal diffusion and mechanical behavior of spruce wood in high temperature environment (up to 180°C). The objective of this part of study was to obtain rheological properties of spruce wood which will be used in future modeling of wood performance in high temperatures. Oven dry samples (30 x 30 x 700 mm3) underwent constant mechanical loading in bending parallel to grain (σmax = 7.3 MPa, load span 600 mm) at three temperature levels, namely 120°C, 150°C and 180°C, respectively. Deflection of the samples was measured using optical non-contact method. Four rheological parameters of Burger’s model, describing immediate elastic, delayed visco-elastic as well as plastic (permanent material change) behavior, were determined which show the strong influence of the temperature on creep propagation. Experimental setup, results and further application in the modeling of high temperature treatment are discussed.