Thermo-structural behavior of soft wood under high X-ray tomography resolution

Abstract

This study consists in better understanding of the influence of the temperature variations on softwood morphological and structural properties. In this context, the X-ray tomography protocol has been used to follow the property variations, a specific tomographic platinum was used to generate thermal flows and to solicit the sample during scans. The study was carried out for temperatures between -5°C and 40°C. The numerical treatments allowed us to investigate the evolution of three microstructural properties of the wood: porosity, specific surface and the pores diameter. In addition, the material exhibits hysteresis behavior along a heating and cooling cycle caused by the anisotropic changes expressed by the swelling / shrinkage of the wooden cell walls. To better quantify these morphological variations, a Digital Image Correlation (DIC) were investigated and the deformation field were calculated function of the wood anatomical structure for both earlywood and latewood. In the tangential direction, the deformation presents a maximum of 1.5 times larger than the radial one. In addition, the deformations caused by heating are larger than those of the cooling cycle. This study provides the literature and future research with promising results especially on the evolution of the wood morphology for better prediction of its macroscopic hygro-thermal behavior.