Experimental investigation of amplification, via a mechanical delay-line, in a rainbow-based metamaterial for energy harvesting

Abstract

We experimentally demonstrate that a rainbow-based metamaterial, created by a graded array of resonant rods attached to an elastic beam, operates as a mechanical delay-line by slowing down surface elastic waves to take advantage of wave interaction with resonance. Experiments demonstrate that the rainbow effect reduces the amplitude of the propagating wave in the host structure. At the same time, it dramatically increases both the period of interaction between the waves and the resonators and the wavefield amplitude in the rod endowed with the harvester. Increased energy is thus fed into the resonators over time: we show the enhanced energy harvesting capabilities of this system.

Hydrodynamics of large wave energy converter arrays with random configuration variations

“…The enhancement of elastic wave energy extraction by a chirped array of solid rods was experimentally shown in De Ponti et al. (2020). In solid-state physics, it is well-known that randomizing the surface of a solar cell leads to large gains in energy absorption (Yablonovitch 1982).…”

“…arrays with slowly modulated inter-body spacing, have sparked recent interest for their ability to increase the absorption bandwidth by 'trapping' waves of different frequencies at different sections of the array (Bennetts, Peter & Montiel 2017;Bennetts, Peter & Craster 2018Archer et al 2020). The enhancement of elastic wave energy extraction by a chirped array of solid rods was experimentally shown in De Ponti et al (2020). In solid-state physics, it is well-known that randomizing the surface of a solar cell leads to large gains in energy absorption (Yablonovitch 1982).…”

Enhanced Energy Harvesting of Flexural Waves in Elastic Beams by Bending Mode of Graded Resonators

“…Particular advances have been recently reported in elastic devices made of arrays of resonant rods for deep elastic substrates (Colombi et al, 2016b;Colombi et al, 2017;Colquitt et al, 2017;Chaplain et al, 2020a) to mode convert Rayleigh (R) into Shear (S) or Pressure (P) waves. Such graded line arrays of resonators have been theorised, designed and manufactured also for energy harvesting applications (Chaplain et al, 2020b;De Ponti et al, 2020;Alshaqaq and Erturk, 2021;De Ponti, 2021). In this context, rainbow reflection and trapping mechanisms are employed to enhance the interaction time between waves and the harvesting system, reporting higher power output as compared to ungraded designs.…”

“…In this context, rainbow reflection and trapping mechanisms are employed to enhance the interaction time between waves and the harvesting system, reporting higher power output as compared to ungraded designs. A straightforward implementation consists into a set of rod resonators of increasing height, which effectively couple with the motion of the A 0 mode, with particularly strong interaction at the longitudinal resonance frequency of the rods (De Ponti et al, 2020). Even if the efficiency of the proposed designs has been verified numerically and experimentally, the use of axial resonators could be a problem for both fabrication and proper connection of the piezoelectric patches.…”

Topological Rainbow Trapping for Elastic Energy Harvesting in Graded Su-Schrieffer-Heeger Systems

“…Shown in Fig. 1(b) is the, now conventional, graded metawedge structure [38], that has recently been utilized for energy-harvesting purposes [42,45]. This consists of periodically spaced rods, which increase in height through an adiabatic grading; in each subsequent cell the rod height is linearly increased, with the unit-cell width remaining constant.…”