Soutenance de thèse : Giovanna LACERRA
Soutenance d'une thèse de doctorat de l’Université de Lyon en cotutelle internationale entre LA SAPIENZA-Università di Roma (Rome, Italie), et l’INSA Lyon (Villeurbanne, France)
Friction Induced Vibration as a result of system response and contact dynamics: a newer friction law for broadband contact excitation
Doctorante : Giovanna LACERRA
Laboratoire INSA : LaMCoS
Ecole doctorale : ED162 MEGA
Friction-induced vibrations are a complex phenomenon which arises each time two surfaces undergo relative sliding. During the last decades, a significant amount of experimental and numerical works dealt with friction-induced vibrations, while the simulation of the dynamic excitation from frictional contacts has always been a real challenge to face. In this research framework, this work is addressed to the investigation of the Friction-Induced Vibrations, carrying on at the same time experimental and numerical analyses, introducing a new numerical approach to reproduce the local dynamic excitation from the contact and its effect on the vibrational response of the system, without significant increase of the computational costs. The mechanical system, object of the investigation, is composed by two steel beams in frictional contact during relative motion. A parametrical experimental campaign has been conducted to analyse the effects of three main contact parameters on the magnitude and frequency content of the induced vibrations: the relative sliding velocity, the normal load and the surface roughness. In parallel, a numerical model has been implemented to reproduce the local dynamic excitation from the contact and its effect on the vibrational response of the system. A new friction law has been introduced in the model, proposing the use of a perturbative term in the friction coefficient in order to simulate the effects of the contact excitation on the system dynamics. The inclusions of the local dynamic excitation, due to the contact phenomena, by the perturbation term of the friction coefficient allows to correctly reproduce the friction-induced vibrations without introducing a representation of the real surface topography, saving then computational time. With the introduction of this friction law into the numerical model, the comparison between the measured friction-induced vibrations and the ones simulated numerically showed good correlation, validating the proposed friction law.
Amphithéâtre CNRS Rhône-Auvergne (Villeurbanne)