Functionally Graded Piezoelectric Composites for Strain Energy Harvesting in Car Tyres.

The pressure of automotive tyres is an important factor with regards to the user's safety, tyre wear/lifetime, and vehicle fuel consumptions. As a result, a key device which is now compulsory by law in the U.S. and most of Europe, is an electronic Tyre Pressure Monitoring System (TPMS). These are often fitted in the tyre cavity and are powered off self-housed batteries in order to achieve the wireless connection linking to the car dashboard. Unfortunately the use of batteries in this application presents several challenges including their limited life cycle, difficult accessibility for maintenance, and issues of recycling and disposal. A potential solution to the high reliance on batteries is the implementation of new energy harvesting sensors based upon the direct piezoelectric effect. This is essentially the conversion of mechanical energy to electrical energy via materials exhibiting piezoelectric properties.
The high-strain environment in automotive tyres is inevitable, so the ability to convert the resulting deformation energy into a useful electrical supply is a great benefit. Previous research and present devices have focused heavily on piezo-ceramics due to their ideal piezo-functional behaviour. However, these materials are brittle and unreliable under the high operating strain conditions. Resulting solutions are often more complex and therefore expensive. The cheaper alternatives are polymer-based devices, which have the benefit of being flexible but the operation temperatures of the automotive tyre pose challenges for their incorporation.
This project aims to develop innovative tri-phase composites based upon piezo-ceramic particulates within a porous-polymer system. The novel composite should tailor the constituent material properties for easy integration into the tyre itself, including functional stability within the high operating conditions. Additionally, the design aims to enhance the energy harvesting ability and meet the potential demand for low-cost mass production.
Optimisation of the properties for this application will involve careful design of the microstructure, including the influence of topological factors. The connectivity, morphology and size distributions of both pores and ceramic particulates will be investigated alongside different fabrication methods. The relationship between these microstructural features and final electromechanical properties in the composite will be explored via a new model. Essential research in the project will also be the individual electro-thermo-mechanical studies of the constituent phases, both via the literature and experimental outcomes.
The overall project objective is to develop a self-powered system based on existing TPMS with the potential for mass production. The optimisation of energy harvesting figures of merit will need to be assessed by deformation tests on the flexible composite films and analysis undertaken on compatible electrodes. Preliminary prototype testing will then help characterise the component feasibility.
The research work is relevant to the EPSRC as self-powering devices are being sought for advancing wireless technologies with the potential to benefit many areas of everyday live via the Internet of Thing (IoT). Additionally, the project focuses heavily on innovative design and material developments within the field of engineering.