Full text
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| Author(s): |
Danilo Braghini
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Mecânica |
| Defense date: | 2024-07-12 |
| Examining board members: |
José Roberto de França Arruda;
Alberto Luiz Serpa;
Carlos De Marqui Junior
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| Advisor: | José Roberto de França Arruda |
| Abstract | |
Active metamaterials have been in the spotlight due to their flexibility and the possibility of tuning; however, there appears to be a significant gap in the literature regarding active metastructures stability and performance. These materials may exhibit topological behavior, which can overcome the sensitivity to manufacturing variability and defects. In this context, designing active metamaterials with skin modes associated with the physics of non-Hermitian systems is an important and challenging task. The skin modes had previously been observed in quantum systems and have recently been reproduced in classical mechanics, where potential technological applications include vibration and noise control, wave filtering and multiplexing, highly sensitive sensors, and control of synthetic filaments and membranes in biological media. Nevertheless, such active metastructures are intrinsically unstable. This work addresses the problem of active metamaterial stability and is motivated to reduce the need for heuristic solutions in designing non-Hermitian active metastructures. The main contribution relies on using simple one-dimensional spring-mass-damper arrays to investigate the stability limits of the closed-loop metastructure and a metric of the directional propagation caused by the skin effect, which characterizes the desired performance. The performance of any topological mode cannot, though, be analyzed with disregard for the topological nature of the metamaterials and its implications in the resulting metastructure dynamics. Thus, this work also provides an extensive and general view of periodic systems with periodically applied non-reciprocal feedback interactions, encompassing different kinds of feedback laws, both local and non-local, in lumped-parameter and distributed-parameter systems, damped and undamped. On the one hand, spectral models for longitudinal wave motion are used to show the particularities of the dispersion diagrams of this family of metamaterials. On the other hand, using time-integration schemes based on a general state-space framework, time-domain responses are computed to analyze the odd resultant dynamics and associated stability issues (AU) | |
| FAPESP's process: | 21/05140-1 - Non-Hermitian metamaterials and non-reciprocal metastructuras |
| Grantee: | Danilo Braghini |
| Support Opportunities: | Scholarships in Brazil - Master |