The Contribution of numerical simulation for the diagnosis of the conservation of art objects: Application to Antonio Santucci’s armillary sphere of the 16th century

Antonio Santucci’s armillary sphere is one of the symbols of the wealth of the world cultural heritage: it is an elaborate representation of the geocentric universe as it was known at that time. Its exceptional dimensions (more than 3 meters high) make it an object which is considered as a complex structure, built with a technique of mixite made of nail-laminated timber. Constructed at the end of the 16th century, this sphere has suffered wear and tear, mostly due to the combined effects of gravity loads over time and environmental agents (such as variations in the relative humidity of the air), as well as means of exposure of the object. The purpose of this research project is to study delayed phenomena, and it lies in the evaluation of the coupled mechano-sorptive effects likely to generate a critical state which would threaten the stability and the durability of the structure. This study highlights a problem which is already very real, even though irreversible consequences may not appear until the future. This work shows the importance of taking into account the variations in relative humidity undergone by the environment in which the sphere is exposed. These changes are at the origin of increasing deformations which could soon become prejudicial to the satisfactory conservation of the object.