Abstract
Until canvas became the most popular support medium in the 16th century, wood was used in numerous paintings which represent today a significant part of our cultural heritage, particularly in museums and churches. A few centuries later, wooden panel paintings exhibit cupping deformations: this cupping is generally interpreted as the consequence of asymmetrical moisture exchanges through panel thickness due to the painted layer. It is also known that wood growth rings and orthotropic orientation are possible causes of deformations due to drying. History of the climatic variations near the panel raises the complex question of time-dependant (thermo-hygro-mechanical) behavior of wood. Better understanding of such behavior could help wood scientists and curators in taking decisions relating to panel transport or museum climate regulations. We suggest a general mechanical approach of this problem, dealing with both material (wood) and structure (panel) point of view. The method includes experimental, theoretical and numerical aspects. Particular attention is put on interaction between wood material (anisotropy, hygromechanical couplings) and the structural level (sawing pattern of panel, joints between planks). A numerical calculation tool is developed, based on orthotropic plate theory and existing heat and mass transfer formulation: numerical simulations are performed to discuss the conservation of a 500 years old wooden panel located in a French church.