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Mechanistic approach for prediction of cutting forces are showing limits when it comes to enhance the cutting force modelling for specific applications of high-value added and thin parts, which are made of difficult-to-cut materials such as titanium alloys. This is the reason why precise cutting force modelling is needed in order to avoid deflection during machining. Therefore, this contribution aims to improve the description of the chip formation in cutting force modelling thanks to an original experimental set-up built up to observe in-situ the chip flow and measure the cutting forces during Ti6Al4V turning. This study highlights the fact that the chip flow direction has a significant effect on cutting forces and can be influenced by several parameters. In view of the results obtained, a generalised chip flow direction model is suggested. Chips morphology observation is also conducted with the purpose of providing experimental observations physical meaning. Afterwards, a cutting force model is proposed which takes into account the chip flow direction influence.

Machining of difficult-to-cut-materials like heat resistant stainless steels leads to the rapid tool wear and tool failure. The analysis of drilling process of these steels is even more difficult as it is not easy to investigate the cutting process at the drill tip. Therefore for this critical operation, modelling of cutting forces is very important. The study of the mechanical loading is based on the cutting tool geometry variation along the cutting edge. This study aims to investigate the drilling of heat resistant stainless steels with two geometries of twist drills, by analyzing specific cutting energy and forces at a global and a local scale.

This study deals with the post-treatment evaluation of the elastic crossbar system already designed and installed on the recently restored panel painting Deposition from the Crossby an anonymous artist from Abruzzo (sixteenth century). After the restoration, the panel and the crossbars were subjected to mechanical tests to identify their elastic characteristics. Then the panel, equipped with the elastic crossbar system, was subjected for about two months to controlled environmental cycles made up of approximately constant humidity periods. During the two months, the forces exerted by the springs and the deformations of both panel and crossbars were continuously monitored. A mathematical model, calibrated on the specific parameters derived from the analysis of the panel, provided the deformation that the panel would have shown without the crossbars; comparing the model output with the measured data provided a restraining effect (RE) of approximately 7% (RE could range between zero – no restraint – and 100% – total restraint). Future developments of this project will define appropriate procedures to design an elastic crossbar system for a given panel, once the expert judgement of restorers has identified the most desirable RE to be achieved.

This research work investigates the possibility to use a hygroscopic model based on Fick’s law to predict the global moisture content variations an historical violin undergoes during a concert. To set up the model to work some input are required such as: the object geometries, the wood species used, the thicknesses, the moisture diffusion coefficients, the permeability of varnished surfaces, the anhydrous masses of the moisture exchanging parts, the sorption isotherms, information often far from being available or measurable. At a first extent, the model was run on the environmental conditions recorded during nine concerts played with the “Cannone” violin (1743) and the computed mass variations compared with the mass variations recorded during the same concerts. The model, set with simplifying conditions and with diffusion coefficients from literature, has shown a very little predictive capacity. On the other hand, the model was tuned on the experimental data using an inverse procedure for moisture diffusion coefficient identification. After the tuning the model has shown a very good predictive ability showing how Fick’s low can be profitably used to assess the mass transfer in a complex heritage object such as a violin. This paper highlights the possibility to successfully use the Fick’s law to model mass transfer in a violin but also makes evident how such models must be tuned with real measurements in order to be effective.