Technological progress leads to mechanical systems characterized by more and more increasing complexity, optimization and power density. As a consequence, higher exchanged/dissipated power per unit area leads to intensification of related dynamic and tribological issues. This project aims to overcome fundamental issues in analyzing, reproducing and control of Friction-Induced Vibrations, in order to provide the necessary tools for the analysis and solving of related issues.
Theoretical and numerical models, in parallel with experiments, will be developed for the reproduction and synthesis of the nonlinear dynamic response to the contact excitation of frictional systems, which brings too often to uncontrollable and unwanted unstable vibrations and noise.
While a general view on Friction-Induced Vibration related issues will be approached, exploiting the experience of the research group in such subject, a direct application to the emerging technologies of Electric Vehicles (EVs) will be focused by the project. The new generation of frictional brakes, forecasted for Electric Vehicle technologies, will be directly addressed, in order to reduce the expected increase of unstable vibrations, which would result in increasing noise and particle emission. A particular focus will be addressed to the newer material pairs and technical solutions forecasted for EVs, applying the fundamental research developments, on an ever-present issue, directly to the newest technological needs.
Individual contributions and methods from the members of the research group, having complementary in-depth expertise on FIV, tribology, dynamics and material science, will be combined into a common pool to promote cross-disciplinary interactions. The goal is to develop novel, cutting-edge approaches and tools to reduce FIV-related social and industrial issues.
As remarked by the wide literature, the numerical simulation of FIV is very complex, because it deals with multi-physics and multi-scale phenomena, which are strongly coupled. One scope of the proposed research is to investigate FIV taking into account the nonlinear phenomena that affects friction-excited dynamical systems, including interface behavior and nonlinear contact stiffness and possibly exploiting them to avoid detrimental dynamical effects, e.g. instabilities.
The present project proposes then to join efforts from the components of the research group, cross-linking different academic competences, including linear and nonlinear dynamics, acoustics, tribology, contact mechanics, and material science. At the same time, the respective components are in active collaboration, on applied issues related to FIV, with several industrial groups in automotive, aerospace, home&buldings and biomechanics. These collaborations will allow for maintaining a close view on the social and industrial applications, which will be affected by the results of the proposed research project.
The integration of the respective domain of competences into a multi-scale and multi-sector approach is the main target of the project and it will provide both innovative hand-on solutions (focused to EV frictional brakes) and explanations to fundamental questions. FIVs have to be investigated not as isolated phenomena or issues, but as generic emergent properties of interactions within or between complex dynamical systems.
If by one side the experimental background of the group on FIVs reproduction and analysis will assure the tools for obtaining new information and features of the phenomena, the increasing power of computational tools (hardware and numerical methods) of the last years laid the foundations for major advances in the comprehension of FIV and, more in general, of dry contacts. The dialog between numerical and experimental analysis, with a complementary approach accounting for both the system dynamics, the interface response and the bulk and surface material behavior will enhance the potentiality in obtaining fundamental advances in the subject.
Moe in detail, the project wishes to outcome with several specific advancements on the actual challenges in modelling, reproducing and controlling of FIVs:
- Contact laws will outcome from experiments on the forecasted pairs of contact materials and implemented into the numerical models;
- The highlighting of nonlinear unstable responses and their physical origin is expected from the theoretical and numerical modelling of the phenomenon, validated by the experiments;
- Instability maps and criterions for the influence of the key factors are expected as a result from the parametric experimental campaigns, together with the interpretation of the trends by numerical simulations.
- The stability criterions will have not only a theoretical interest, but will be practical information for designers, with direct applicability to EV frictional brakes; The project will provide valuable numerical/theoretical tool for FIV, particularly for the materials/expected designs of the new EV brake;
- The research project will provide valuable knowledge in a field such as EV, that is considered the breakthrough technology in mobility, with the aim of prevent noise and reduce particle emissions.
Finally, if the expected results will bring advancements on the fundamental understanding of FIV, the development of the tests and the modelling on a benchmark representative of EV brakes will allows for short term social and industrial impacts by the direct application on this overcoming technology.