Improving the Electric Response of a Cantilever Piezoelectric Energy Harvester by Constraining Tip Curvature

Abstract

The paper studies the influence of tip curvature on the electrical response of a piezoelectric energy harvester, on a direction other than the charge generation one. Finite element analyses were conducted for the given piezoelectric transducer, which show an increase in the voltage output if blocking the tip curvature on yOz plane between two bars, leaving free only the deflection on xOz plane. The comparison was made between cantilever tip constrained with bars and cantilever with an equivalent proof mass respectively. The simulations in COMSOL Multiphysics are furthermore validated by experimental laboratory tests, confirming the increase of the electric output potential with ~8%. This occurs due to inducing higher stress into the structure by blocking its tip curvature. The frequency response, defined between base excitation and the output voltage, was determined using an impedance analyser. The bars also act as a proof mass, thus decreasing the resonant frequency optimally down to the vibration frequencies of an oil-free compressor’s downstream pipe on which the transducer will be mounted in order to harness the inherent vibrations and subsequently power wireless sensors.

Vibration Analysis of a Twin-Screw Compressor as a Potential Source for Piezoelectric Energy Harvesting

“…The experimental tests conducted in 2018 rendered ~4.2 V/g with no tip mass [30]. The tests in early 2020 outlined 3.280 V/g in the same conditions with no mass [31]. We obtained a drastically decreased voltage response of 1.333 V/g with no tip mass and 5.345 V/g with a 7.4 g tip mass in our latest publication at the end of 2022 [26], which confirmed our apprehension that this piezoelectric device is getting near the end of its lifespan.…”

Optimization of cantilever piezoelectric harvester to triangular shape with material reduction using finite element analysis

“…The PEH has previously been tested in laboratory [ 39 , [53] , [54] , [55] ] and on a gas turbine test bench [ 56 , 57 ], focusing on the voltage output at resonance. The experimental harvesting system illustrated in Fig.…”

“…Our previous experimental research [ 39 , 53 ], employing the physical rectangular piezoelectric structure, brought us to this paper. We compared the experimental results to the simulation results in Ref.…”

“…We have paid attention to keeping the von Mises stress within reasonable limits that would not exceed ∼80 MPa, obtained in the simulations for the rectangular cantilever with inertial mass of 4.0 g. This mass value is in accordance with the physical experiment, and is much below cantilever materials' maximum tensile strengths [ 37 ] and below PZT-5H bending strength of 114.8 MPa found by Anton et al [ 38 ]. However, when adding an electric circuit simulating the load impedance of 1 MΩ + 50 pF (input impedance of the spectrum analyser [ 39 , 40 ]), the stress is reduced to 78.5 MPa due to the dissipative nature of the electrical resistance that manifests as an equivalent mechanical damping. This stress value was further used in the comparative study evaluating the shapes’ performances in same stress conditions.…”

Numerical Analyses on the Responses of Unimorph and Bimorph Piezoelectric Harvesters in Time Domain

“…The simulated geometry was inspired by Mide PPA-4011 piezoelectric harvester (Fig. 1), which has been simulated and tested in previous research works [12][13][14][15]. The physical harvester has four PZT-5H layers and complicated internal circuitry regarding the electrical connections, which is not disclosed by the manufacturer [16].…”