Dipartimento d'Ingegneria

Valigi Maria Cristina

Valigi Maria Cristina

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Additional Details

  • Phone
    075 585 3724
  • Mobile Phone
    329 410 3870
  • Role
    Professore associato - Associate professor
  • Area
    Meccanica applicata alle macchine - Mechanics of machines
                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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