Design, and characterisation of impact based and non-contact piezoelectric harvesters for rotating objects

Abstract

This thesis highlights two different methods of extracting electrical energy from rotational forces using impact based and non-contact based piezoelectric harvesters. In this work, the centripetal force is used as the main acting force that causes the piezoelectric harvesters to produce output power. In order to achieve this, the harvesters are mounted in a horizontal position while the rotational forces are applied. The impact based piezoelectric harvester consists of a tube with one piezoelectric pre-stressed beam mounted at each end of the tube. A ball bearing that has the freedom of movement between the two ends of the tube generates an impact force on the piezoelectric structures due to the effect of the centripetal force. The impact based piezoelectric harvester is modelled and its behaviour is analysed and verified experimentally. For the non-contact piezoelectric harvester, the applied force on the piezoelectric element is produced by a magnetic levitation system without the need for a direct physical contact. The impact of the magnet size and shape is studied and the results become a guideline that is used to design and optimize the piezoelectric harvester. The model of the non-contact piezoelectric harvester is derived and verified experimentally in order to analyse its behaviour at different boundary conditions. A comparison between the two harvesters is carried out. This includes highlighting the advantages and the limitations of each of them.

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Identifiers

ORCID for N.M. White: orcid.org/0000-0003-1532-6452

ORCID for M.J. Tudor: orcid.org/0000-0003-1179-9455

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