Study of asynchronous modal oscillations in pre-tensioned heavy-chains

• Grant number: 17/12779-3
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: December 01, 2017
• End date: June 20, 2022
• Field of knowledge: Engineering - Civil Engineering - Structural Engineering
• Principal Investigator: Carlos Eduardo Nigro Mazzilli
• Grantee: Eduardo Ascenso Reis Ribeiro
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 18/12858-3 - Modal asynchronicity: application to energy-harvesting systems, BE.EP.DD

Abstract

The concept of asynchronicity in dynamical systems is not unique. In fact, one finds in the literature several examples where oscillations are called asynchronous, in different scenarios, hindering the definition of a general description of the phenomenon. Regarding modal vibration analisys, some works suggest that asynchronicity could be related to phase differences between generalised displacements and velocities in non-linear systems. However, recent publications show that asynchronous vibration modes are possible even in simpler linear systems, with few degrees-of-freedom (d.o.f.), where asynchronicity is seen under the perspective of localisation, that is, when part of the structure remains at rest during a modal oscillation. In this respect, the "Study of asynchronous modal oscillations in pre-tensioned heavy-chains" proposes to analyse the asynchronicity phenomenon through the localisation in a number of models: low-hierarchy ones (bar-models with three-d.o.f.), medium-hierarchy ones (bar-models with many d.o.f.) and high-hierarchy ones (cylindrical shells). Preliminary results show that asynchronous vibration modes are possible in the two first classes of models, provided the mechanical-geometric properties of the strucure are properly chosen. The discovery of asynchronous modes in higher hierarchy models, besides being a step forward to the definition of a general concept of asynchronicity, will be very important in practical terms. It is believed that the domain of the asynchronicity phenomenon in complex structures will allow, for example: to project structures wchich are safer against earthquakes and impacts (e.g.: nuclear plants, surgery rooms, brigdes, high buildings etc), reducing or even eliminating the necessity of expensive vibration control devices; to harvest electric energy from the concentration of kinetic energy in part of a system; optimise the signal amplification in microsensors. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

MENDES, BRENO A. P.; MAZZILLI, CARLOS E. N.; RIBEIRO, EDUARDO A. R.. Energy harvesting in a slender-rod model with modal asynchronicity. NONLINEAR DYNAMICS, v. 99, n. 1, SI, p. 611-624, JAN 2020. (17/12779-3)

MENDES, BRENO A. P.; MAZZILLI, CARLOS E. N.; RIBEIRO, EDUARDO A. R.. Energy harvesting in a slender-rod model with modal asynchronicity. NONLINEAR DYNAMICS, v. 99, n. 1, p. 14-pg., 2020-01-01. (17/12779-3)

RIBEIRO, EDUARDO A. R.; MAZZILLI, CARLOS E. N.; LENCI, STEFANO. Influence of Geometric Nonlinearities on the Asynchronous Modes of an Articulated Prestressed Slender Structure. JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME, v. 141, n. 2, APR 2019. (17/12779-3)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

RIBEIRO, Eduardo Ascenso Reis. Modal asynchronicity in structures: a discussion on the admissibility of asynchronous vibration modes in structural systems and their potentiality for energy harvesting and vibration control.. 2022. Doctoral Thesis - Universidade de São Paulo (USP). Escola Politécnica (EP/BC) São Paulo.