Nonlinear energy harvesting from vibratory disc-shaped piezoelectric laminates

Implementing resonators with geometrical nonlinearities in vibrational energy harvesting systems leads to considerable enhancement of their operational bandwidths. This advantage of nonlinear devices in comparison to their linear counterparts is much more obvious especially at small-scale where transition to nonlinear regime of vibration occurs at moderately small amplitudes of the base excitation. In this paper the nonlinear behavior of a disc-shaped piezoelectric laminated harvester considering midplane-stretching effect is investigated. Extended Hamilton’s principle is exploited to extract electromechanically coupled governing partial differential equations of the system. The equations are firstly order-reduced and then analytically solved implementing perturbation method of multiple scales. A nonlinear finite element method(FEM) simulation of the system is performed additionally for the purpose of verification which shows agreement with the analytical solution to a large extent. The frequency response of the output power at primary resonance of the harvester is calculated to investigate the effect of nonlinearity on the system performance. Effect of various parameters including mechanical quality factor, external load impedance and base excitation amplitude on the behavior of the system are studied. Findings indicate that in the nonlinear regime both output power and operational bandwidth of the harvester will be enhanced by increasing the mechanical quality factor which can be considered as a significant advantage in comparison to linear harvesters in which these two factors vary in opposite ways as quality factor is changed.

A nonlinear triboelectric nanogenerator with a broadened band-width for effective harvesting of vibration energy

A narrow resonance bandwidth of an energy harvesters limits its response to the wide frequency spectrum in ambient environ-ments.This work proposes an addition of a nonlinear restoring force applied to a triboelectric nanogenerator(TENG)to tune and broaden the resonance bandwidth.This restoring force is applied by permanent magnets at both sides of the slider and two external magnets.The noncontact strategy is adopted between the slider and the grating electrodes to avoid the wear of electrodes and energy loss caused by friction.The results show that compared with the linear system,the nonlinear noncontact TENG(NN-TENG)can increase the peak current from 6.3μA to 7.89μA,with an increment of about 25%,increase the peak power from 650μW to 977μW,increasing by about 50%,and increase the bandwidth from 0.5 Hz to 7.75 Hz,increasing by about1400%.This work may enable a new strategy to boost the bandwidth and output power of TENG through nonlinear oscillators.

Dynamics of triboelectric nanogenerators: A review

Triboelectric nanogenerators(TENGs)represent a promising next‐generation renewable energy technology.TENGs have become increasingly popular for harvesting vibration energy in the environment due to their advantages of lightweight,broad range of material choices,low cost,and no pollution.However,issues such as input force irregularity,working bandwidth,efficiency calculation,and dynamic modeling hinder the use of TENGs in industrial or practical applications.In this paper,the modeling process of the dynamical system of a TENG is reviewed from the perspective of energy flow.In addition,this paper reviews the main contributions made in recent years to achieve optimized output based on springs,magnetic forces,and pendulums,and introduces different ways to increase the bandwidth of TENGs.Finally,the main problems of TENGs in the process of harvesting vibration energy are discussed.This review may serve as a practical reference for methods to convert irregular mechanical input sources into optimized output performance toward the commercialization of TENGs.