Abstract
Conservation or restoration of many ancient wooden artefacts such as panel paintings is madedifficult. In addition by issues linked to wood ageing, but also by the delicate situationsoriginaling from asymmetrical moisture transfer phenomena through surface layer and woodensubstrate. Conservators have tried to eradicate panels curvatures by moistening and flatteningby pressure ; or simply in term of restoration act, by panel thinning followed by gluing on arigid support. Between fortunate handling and absence of environmental control, some paintlayers flaked material was partially lost, cracks opened. Indeed, the artefacts from culturalheritage that we handle are the witness of ancient times and practices, and may provide keysto the understanding of long-term behaviour of wooden structures.First, we have focused on the basic understanding of wood aging, we have made hygro-thermaltreatment at 120°C for several humidities and at 50°C by hydric cycles on poplar samples(Populus alba). We underlined physical and chemical process and the reversible effect of heattreatedwood. Then we studied the behaviour of a painted panel part, and the relation betweenwood and preparatory layer. Our work shows clearly that the hygromechanical behaviour ofthe preparatory layer is very dependent on its composition, and that it is important to knowprecisely the layer composition before being able to analyse the global behavior of a panelpainting. Finally, our work concerned experimental and numerical study of hygromechanicalbehaviour of a wooden panel, based on continuous mass weighting and measurement of strainby stereo-correlation during hygrothermal fluctuations of the environment. We decoupled experimentallythe different components occurring in hygromechanics of panel painting, and weworked to set up a numerical tool allowing the simulation of observed phenomena. This thesispresents, on a fundamental point of view, the wooden panel behavior under climatic fluctuations,linking with cultural conservator actors (such as curators, conservators, scientists fromcultural heritage . . .) in order to develop tools to decision help.