Marco Fioravanti

Numerical modeling and assessment of the Ebe schooner-brig

The Ebe schooner-brig was built in 1921 and sailed the Mediterranean Sea for almost 40 years before being dissected into 90 parts to be transported to Milan (Italy). There, the schooner was reassembled, and the naval pavilion of the National Museum of Science and Technology was built around the ship. After 45 years in the museum, the ship presents significant deformations of both the deck and the keel, particularly in correspondence with the external supports. Despite several interventions in the past and a recent restoration, the deformation phenomenon is still worrying, and the real cause has yet to be understood. Experts have already advanced some hypotheses, often in opposition to one another; unfortunately, a continuous monitoring of the ship deformation has not been installed. In the present study, the schooner structure is modeled with the commercial finite element code Diana, considering a two-dimensional model of the ship section and a three-dimensional model of the whole schooner, accounting for different levels of details and discretization. The results obtained allow for a deeper understanding of the stress-strain field in the schooner, providing a first safety assessment and useful hints for the design of the monitoring and future interventions.

The influence of dovetailed cross beams on the dimensional stability of a panel painting from the Middle Ages

Abstract This paper describes experiments carried out to determine the influence of dovetailed cross beams on the dimensional stability of a panel painting from the Middle Ages. Besides a serious cup (transverse distortion), the panel featured an unusual longitudinal distortion, a bow, mostly originating from bending in the proximity of the middle cross beam. Because of its localized occurrence, bending appeared to be caused by the crossbeam somehow pushing on the walls of its channel. Thanks to the cooperation offered by the curator and the restorer, some non-damaging tests were performed to measure the distortions of the panel, with and without the cross beams, after conditioning it in different climates. Processing and analysis of the measurement results demonstrated that the bow of the panel increases as the wood moisture content decreases. This led to the conclusion that the bow is actually produced by forces exerted by the cross beam along the panels length, according to a mechanism named thrust transformation. By this mechanism the cross beam partly transforms the panels tendency towards cupping, into a bow distortion.

Non-invasive wood identification of historical musical bows

We identified the wood of the sticks of eight bows in the historical collection of musical instruments in the Galleria dell’ Accademia in Florence. Wood identification was carried out non-invasively (i.e., without sampling wood from the original objects), because the removal of samples from fine musical instruments will affect their aesthetic integrity and/or functional quality. Identification attempts using reflected light microscopy of wood surfaces, gave only partial results due to the poor quality of the surfaces and the particular geometry of the sticks that does not have any transverse surface. Application of Synchrotron light X-ray microtomography (µCT) in phase-contrast mode to the whole sticks allowed us to obtain stacks of transverse-sectional images that, processed as virtual volumes, revealed several anatomical features. With µCT it was possible to identify three bows as Brosimum guianense (Moraceae), one bow as Caesalpinia echinata (Caesalpiniaceae), and four bows as Manilkara sp. (Sapotaceae).