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

汽车轮胎的压力是关于用户安全、轮胎磨损/寿命和车辆燃料消耗的重要因素。因此，现在美国和欧洲大部分地区的法律强制要求的关键设备是电子轮胎压力监测系统（TPMS）。这些通常安装在轮胎腔中，并由自带电池供电，以实现与汽车仪表板的无线连接。不幸的是，在这种应用中使用电池带来了几个挑战，包括它们有限的生命周期、难以维护以及回收和处置的问题。高度依赖电池的一个潜在解决方案是基于直接压电效应的新能量收集传感器的实现。这本质上是通过具有压电特性的材料将机械能转换为电能。汽车轮胎中的高应变环境是不可避免的，因此能够将由此产生的变形能转换为有用的电力供应是一个巨大的优势。由于压电陶瓷具有理想的压电功能特性，以往的研究和目前的器件都集中在压电陶瓷上。然而，这些材料在高工作应变条件下是易碎的和不可靠的。由此产生的解决方案往往更复杂，因此也更昂贵。更便宜的替代品是基于聚合物的设备，其具有灵活的优点，但汽车轮胎的工作温度对它们的结合提出了挑战。该项目旨在开发基于多孔聚合物系统中的压电陶瓷颗粒的创新三相复合材料。新型复合材料应调整组成材料的性能，以易于集成到轮胎本身中，包括在高操作条件下的功能稳定性。此外，该设计旨在提高能量收集能力，并满足低成本大规模生产的潜在需求。优化这种应用的性能将涉及仔细设计的微观结构，包括拓扑因素的影响。孔和陶瓷颗粒的连通性，形态和尺寸分布将随着不同的制造方法进行研究。这些微观结构特征和最终的机电性能之间的关系，在复合材料将通过一个新的模型进行探索。该项目的主要研究还将通过文献和实验结果对各个组成阶段进行电-热-机械研究。项目的总体目标是在现有TPMS的基础上开发一种具有大规模生产潜力的自供电系统。能量收集优值的优化将需要通过对柔性复合膜的变形测试和对兼容电极进行的分析来评估。初步的原型测试将有助于验证组件的可行性。这项研究工作与EPSRC有关，因为自供电设备正在寻求推进无线技术，有可能通过物联网（IoT）使日常生活的许多领域受益。此外，该项目重点关注工程领域的创新设计和材料开发。

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.