Structural vibration energy harvesting via bistable nonlinear attachments

A vibration-based bistable electromagnetic energy harvester coupled to a directly excited host structure is theoretically and experimentally examined. The primary goal of the study is to investigate the potential benet of the bistable element for harvesting broadband and low-amplitude vibration energy. The considered system consists of a grounded, weakly damped, linear oscillator (LO) coupled to a lightweight, damped oscillator by means of an element which provides for both cubic nonlinear and negative linear stiness components and electromechanical coupling elements. Single and repeated impulses with varying amplitude applied to the LO are the vibration energy sources considered. A thorough sensitivity analysis of the system's key parameters provides design insights for a bistable nonlinear energy harvesting (BNEH) device able to attain robust harvesting efficiency. Energy localization into the bistable attachment is achieved through the exploitation of three BNEH main dynamical regimes; namely, periodic cross-well, aperiodic (chaotic) cross-well, and in-well oscillations. For the experimental investigation on the performance of the bistable device, nonlinear and negative linear terms in the mechanical coupling are physically realized by exploiting the transverse displacement of a buckled slender steel beam; the electromechanical coupling is accomplished by an electromagnetic transducer

Il comfort nelle passerelle pedonali. Parte 2: un caso studio

L’articolo è dedicato alle verifiche di comfort nelle passerelle pedonali. Nella prima parte sono stati confrontati gli standard progettuali previsti da alcune delle normative e linee guida (sia nazionali, sia internazionali) più accreditate. In questa seconda parte, come esempio paradigmatico, si effettua la verifica di comfort di una passerella pedonale in acciaio di recente costruzione, mostrando come il soddisfacimento dei requisiti prestazionali richiesti necessiti un opportuno adeguamento del sistema strutturale. Si propone, infine, una possibile soluzione progettuale, basata sull’utilizzo di un sistema di mitigazione con smorzatore a massa accordata.The work focuses on the comfort analysis of pedestrian walkways. In the first part the design rules provided by some of the most reliable codes and guidelines (both national and international) have been explicated and compared. In this second part, as a paradigmatic example, the comfort analysis of a lately built steel footbridge is carried out, showing how the fulfillment of the required performances needs a proper adaptation of the structural system. A possible design solution, based on the use of a tuned mass damper as mitigation system, is eventually proposed

Il comfort nelle passerelle pedonali. Parte 1: analisi comparativa dei criteri normativi

L’articolo è dedicato alle verifiche di comfort nelle passerelle pedonali. Nella prima parte, dopo aver richiamato i concetti basilari che regolano la fisica del problema, sono enucleati e confrontati gli standard progettuali previsti da alcune delle normative e linee guida (sia nazionali, sia internazionali) più accreditate. La scelta di una filosofia progettuale rispetto alle altre disponibili è quindi commentata e giustificata. Seguirà una seconda parte dedicata alla verifica di comfort di una passerella pedonale in acciaio di recente costruzione.The work focuses on the comfort analysis of pedestrian walkways. In the first part, after a brief overview on the basic concepts governing the physics of the problem, the design rules provided by some of the most reliable codes and guidelines (both national and international) are explicated and compared. The choice of a design philosophy among the several available ones is then commented and justified. The second part will deal with the comfort analysis of a lately built steel footbridge

Vibration energy harvesting from impulsive excitations via a bistable nonlinear attachment

A vibration-based bistable electromagnetic energy harvester coupled to a directly excited primary system is examined numerically. The primary goal of the study is to investigate the potential benet of the bistable element for harvesting broadband and low-amplitude vibration energy. The considered system consists of a grounded, weakly damped, linear oscillator (LO) coupled to a light-weight, weakly damped oscillator by means of an element which provides both cubic nonlinear and negative linear stiffness components and electromechanical coupling elements. Single and repeated impulses with varying amplitude applied to the LO are the vibration energy sources considered. A thorough sensitivity analysis of the system's key parameters provides design insights for a bistable nonlinear energy harvesting (BNEH) device able to achieve robust harvesting efficiency. This is achieved through the exploitation of three BNEH main dynamical regimes; namely, periodic cross-well, aperiodic (chaotic) cross-well, and in-well oscillations

Vibration energy harvesting via a bistable nonlinear attachment. Experimental study

A bistable nonlinear electromagnetic energy harvester coupled to an impulsively excited primary linear oscillator has been experimentally investigated. The design of the energy harvesting system was guided by a preliminary numerical study, which predicted a favorable dynamic regime for harvesting purposes. The harvesting system consisted of a lightweight permanent magnet, moving within a stationary coil, nonlinearly coupled to a grounded, weakly damped linear oscillator through a prebuckled, bistable slender steel beam which exhibited both cubic nonlinear and negative linear stiffess behaviors in transverse response along its weak axis. This paper provides the results of an experimental investigation, illustrating the capacity of the bistable element to dramatically enhance harvesting efficiency when subjected to broadband, low-amplitude vibration, executing large amplitude oscillations between the two stable equilibrium positions. Single and repeated impulses of varying amplitude applied to the LO are employed as system inputs, and it is shown, both experimentally and through numerical simulations, that robust harvesting effciency is achieved primarily through periodic cross-well oscillations, particularly at low levels of input energy