Local moisture content and swelling strain in wood investigated by NMR and X-Ray microtomography

Abstract : The aim of this paper is to study the swelling properties of wood in relation to its moisture content by using non-invasive methods. The NMR methods lead to determine, on the one hand, the distribution of the moisture content in the sample (by Magnetic Resonance Imaging MRI) and, on the other hand, the evolution of the water into the porous network (by longitudinal relaxation time T1). X-Ray microtomography observations coupled with volumetric digital image correlation (V-DIC) give access to 3D-displacement fields from which local strain heterogeneities have been derived. It is shown that deformation is non homogeneous in relation to the moisture content in early and latewood.