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Cyclic response of friction damped mechanical systems - PhD thesis - part II
This is the "part II" of my PhD thesis.
It addresses the problem of finding the dynamic cyclic response of mechanical systems experiencing dry friction with a particular focus on the influence of varying normal and tangential loads. I first start from a single degree of freedom model and gradually increase the complexity of the system. In the last chapter I address a system with 12 degrees of freedom which shows localized vibration states, that are very similar to solutions known in other physics fields like optics and fluid dynamics.
In chapter 7 a very simple model of structure subjected to dry friction is studied, constituted by a single degree of freedom system subjected to a periodical tangential excitation and a (possibly) varying normal load. First we compare the quasi-static solution with the dynamic solution in the limit of very low excitation frequency, then we study (in the bounded regime) how the peak displacement and dissipation is related to the phase shift between the normal and the tangential load. In chapter 8 the dynamical behaviour of a mass-spring-viscous damper structure linked to a massless Coulomb damper is studied with attention to the regime that minimize the vibration amplitude of the mass. Finally in chapter 9, we study a friction-excited nonlinear oscillator chain, where a polynomial nonlinearity is introduced in the system. We focus our attention on the multiplicity of solutions that are proven to exist in certain parameter ranges which leads to a bifurcation pattern similar to the snaking bifurcations. In the end conclusions and possible developments of the present work are proposed.
The most of the data reported have been published in known international journal papers. A comprehensive list can be found here:
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Interactions and possible collaborations are welcome,