Eventos Anais de eventos
DINAME 2017
XVII International Symposium on Dynamic Problems of Mechanics
Asynchronous modes of vibration in a heavy-chain model
Submission Author:
CARLOS MAZZILLI , SP , Brazil
Co-Authors:
CARLOS MAZZILLI, Stefano Lenci
Presenter: CARLOS MAZZILLI
doi://10.26678/ABCM.DINAME2017.DIN17-0022
Abstract
Asynchronous modes of vibration, characterized by localized free oscillations, are unexpected findings in linear structural systems. Yet, among other examples, they may be found in non-conservative systems, such as those with follower forces, as well as in conservative systems, such as simple portal frames, provided the system parameters are duly calibrated. In the present paper, a three-degree-of-freedom heavy-chain model is also shown to display such a behaviour, depending on the hanging force, the dead weight, the system stiffness, mass and geometric characteristics. Two types of asynchronous modes are seen to exist: the so-called isolated mode, with a single non-null physical coordinate, and the so-called non-isolated mode, with more than one non-null physical coordinate, although still localized. It is curious that in this simple model the companion modes of isolated modes are non-isolated ones, all of them being of course asynchronous. At this stage, a linearized formulation of modal analysis is carried out, leaving to a later moment the discussion of non-linear effects upon the asynchronicity phenomenon. The heavy-chain model addressed here bears similarities with offshore risers, cylindrical reservoirs and cylindrical pressure vessels under pre-stressing. Understanding the asynchronicity phenomenon is the first step towards using it in technological applications, such as vibration control, energy harvesting and micro-sensors.
Keywords
asynchronous modes, heavy chain, localization
