Dipartimento d'Ingegneria

Mechanics of machines - Meccanica applicata alle macchine

Dynamics of machines: Activities regard the modeling and simulation of the dynamical behavior of mechanical systems such as transmission systems, mechanical seals, concrete mixers (planetary mixers, twin shaft and turbine shaft mixers) and rolling mills. This research line includes non-linear dynamic systems, stability and self-excited vibrations, condition monitoring and diagnostics. Particular attention is focused on chatter and stick-slip phenomena.

Wear: The wear analysis process consists of the following elements: examination of the entire tribosystem , characterization of the wear situation, selection of analytical wear relationships, evaluation and verification of wear solutions. Goal of the research is to improve the performances of mechanical components despite to wearing action.

Lubrication: This activities regards numerical modeling and simulations of lubrication in different regimes: hydrostatic lubrication, hydrodynamic full fluid lubrication , mixed lubrication and boundary lubrication. The general approach is devoted to find out models that are in any case related to real and industrial application and the experimental validation.

                Wear is a significant mechanical and clinical problem. To acquire further knowledge on the tribological phenomena that involve freeform mechanical components or medical prostheses, wear tests are performed on biomedical and industrial materials in order to solve or reduce failures or malfunctions due to material loss. Scientific and technological advances in the field of optical scanning allow the application of innovative devices for wear measurements, leading to improvements that were unimaginable until a few years ago. It is therefore important to develop techniques, based on new instrumentations, for more accurate and reproducible measurements of wear. The use of Innovative techinques by means 3d optical scanners represents a new challenge in wear assessment and defining of "digital tribology".
                  The discussion of the use of innovative 3D optical scanners and an experimental procedure to detect and evaluate wear are presented in the research paper [ http://www.mdpi.com/1996-1944/10/5/548 ]  where this technique with other wear evaluation methods is compared for industrial components and biomedical devices.

by Maria Cristina Valigi, Silvia Logozzo and Saverio Affatato.
We have investigated  mechanical face seals   used  as sealing devices of  pumps in cooling  systems of automobile engines. Sometimes the mechanical face seals generate undesired acoustic emissions: ringing. Ringing phenomena in mechanical face seals are one of the inconveniences that appears under certain conditions but they are rarely studied because of the difficulty in reproducing these phenomena. Seals may operate in any of the following three lubrication regimes: full film lubrication, mixed lubrication  and  boundary lubrication.
The problem is examined through a lumped parameters model together with a mixed friction tribological model. Numerical simulations compared with experimental results  demonstrate that  the phenomenon is caused by the insurgence of stick-slip vibrations. In addition, the stability threshold is investigated and the influences of some design parameters are evaluated.


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