Modelling and optimisation of a force amplification energy harvester

Abstract

A flexure frame mechanism is a device historically used to amplify the displacement of an actuator with limited travel, such as a piezoelectric stack actuator. Conversely, these mechanisms may be used as a generator to amplify the force applied to piezoelectric transducers. This in turn can greatly increase the harvested power. Previous studies have used a variety of methods to analyse the amplification factor of a flexure frame mechanism operating as an actuator in displacement mode, as opposed to a generator in force amplification mode. The effects on the performance of such a device when operating in force amplification mode are not as well understood. In this study, an analysis of the force amplification of a flexure frame mechanism is conducted. A model of the force amplification factor based on the material properties and geometry of the device is developed for use as an optimisation and design tool. The analytical findings are compared against finite element analysis simulation and experimental results for validation. The effect of the stiffness of the central piezoelectric stack and the maximum stresses developed in the frame are determined to be critical parameters in determining the effectiveness of the mechanism as an energy harvester.

Strongly coupled piezoelectric energy harvesters: Finite element modelling and experimental validation

“…A piezoelectric stack energy harvester (PSEH) with a mechanical transformer was used to study in this work, which is a good example of strongly coupled PEH. Similar harvesters have been widely studied for low-frequency compressive force energy harvesting [31][32][33][34] due to the high electrical power output, which is a result of the force amplification mechanism and the high electromechanical coupling of piezoelectric stacks used [35].…”

Design and dynamic analysis of integrated architecture for vibration energy harvesting including piezoelectric frame and mechanical amplifier

“…Cao et al [31] designed an analytical model to describe the static displacement and force interactions between generic serial-parallel compliant mechanisms and piezo-stacks. Evans et al [32] investigated a force-amplified piezoelectric stack device that was found to have a maximum level of amplification at a low-frequency level. Multi-stage force amplification frames (AFs) were proposed in Refs.…”

Modeling of a Symmetric Five-Bar Displacement Amplification Compliant Mechanism for Energy Harvesting

“…As these competing attributes are often conflicting, a trade-off must usually be made to come up with a compromise, which can be conducted through proper modeling and simulation tools. Compliant mechanisms have been modeled using pseudo-rigid-body models (PRBM) [ 14 , 19 , 20 , 21 , 22 ], or topology optimization methods [ 23 , 24 ]. The mathematical modeling of compliant mechanisms with right-circular and corner-filleted flexure joints have also been performed using Castigliano’s energy theorem [ 25 ], and the principle of virtual work [ 26 ].…”