Exploiting bistable oscillator subharmonics for magnified broadband vibration energy harvesting

Abstract

Recent research on primary battery alternatives for supplying autonomous wireless devices has recently highlighted the advantages of nonlinear oscillators' dynamics and more particularly bistable oscillators' behavior for ambient vibration harvesting. The key property of bistable oscillators compared to linear ones is their enhanced operational frequency bandwidth under harmonic excitation, potentially leading to a better adaptation to the environment. However, the classical frequency response characterization of such devices does not reveal all the possible dynamic behaviors offered by bistable oscillators. Thus, subharmonic motions are experimentally investigated in this letter, and their energy harvesting potential as well as their ability to enhance the bistable generator bandwidth is evaluated. The results obtained with a generator integrating buckled beams for the bistability feature show that, in addition to the commonly considered harmonic behavior, subharmonics allow widening of the useful operating frequency band of the bistable microgenerator by 180% compared to the sole exploitation of the first harmonic motion.

Orbit jump in bistable energy harvesters through buckling level modification

“…Several different behaviors can coexist on the same frequency range, solely determined by its initial conditions. Some of those behaviors are interesting for energy harvesting, namely the common harmonic 1 high orbit (for which the mass moves from one stable position to another at the same frequency as the excitation) [8,9] and the subharmonic 3 high orbit (for which the mass moves from one stable position to another at a frequency 3 times lower than the excitation), as reported by the authors in previous studies [10,11]. However, some other behaviors, namely the low orbits (for which the mass oscillate around one stable position), are not interesting for energy harvesting as they induce low amplitude displacements and thus low energy levels.…”

“…For each of them, a time signal is presented as well as a phase portrait for different excitation frequencies. The steady-state behaviors highlighted in Figure 2 are those the authors reported as an interesting aspect for energy harvesting purpose in a previous work [10], namely the common harmonic 1 orbit and the subharmonic orbits. Subharmonic orbits are defined as follow: for subharmonic n orbit, the mass moves with a frequency n times lower than the excitation frequency.…”

Broadband frequency response of a nonlinear resonator with clearance for energy harvesting

“…4c). This solution is consistent with the recent results by Huguet et al [8] and Syta et al [7] where the subharmonic solutions were present. Here, the beam deflection response is formed in a sequence of peaks depending on impacts in the chosen system geometry and dynamical conditions.…”

“…For instance, possible solutions in double well system resonators [7] are related to the small amplitude single well solution and the large amplitude cross barrier solution. Especially, subharmonic solutions with a large amplitude are very useful for energy harvesting [7,8]. Following the concept of the inverted elastic pendulum which undergoes a bifurcation of single to double equilibria under load of a tip mass [9], we propose a system with the effect of clearance in the clamping.…”

Vibrational tests of a system with two coupled beams and a distributed tip mass

“…Recently, various nonlinear systems where proposed for vibration energy harvesting [1][2][3][4]. They guarantee broadband frequency energy converters important for variable vibration energy sources [5][6][7] comparing to linear devices [8]. The role of nonlinearities [5,6] is important non only in broadening of frequency in the main resonance region through inclination of the resonance curve but also in involving multiple solutions.…”