3D Multiscale Modelling and Characterisation of the Coupled Electromechanical Behaviour of Novel Smart Piezoelectric Nanocomposites

* 背景：我新提出的研究计划的目的是产生新的知识，以准确地建模，建模和开发下一代轻质智能压电纳米复合材料（SPNC），用作传感器，执行器和能量采集器，更好地了解控制其机电行为的基本参数。新的SPNC制造使用优先对齐的纳米线（NW）阵列与有限的间距和封装在环氧树脂基体中的纳米表面电极。由于其出色的机电性能，氧化锌和氮化镓纳米线被选中。压电系数定义了NW和SPNC的机电行为;在小场条件之外，这些系数与温度有关。** 研究计划：长期目标是产生新的知识，导致新的SPNC设计和分析工具，需要以下短期目标：*1。确定有效的机械性能和直接压电系数的均质传感器光纤的直接压电效应，通过施加机械应变在恒定的电场，使用新的混合分子动力学（MD）-密度泛函理论（DFT）的NW由环氧树脂矩阵包围。*2。利用DFT-MD计算了均质化致动器光纤的有效力学性能和匡威压电系数，以实现匡威压电效应。*3。通过使用3D分层多尺度策略扩展目标1中开发的有效传感器纤维网络来确定SPNC的散装机电特性。*4。通过使用修改的微观力学和均匀化方案以及新的网络识别策略，按比例放大目标2中开发的有效致动器纤维网络，计算SPNC的体机电性能。*5。开展广泛的实验工作，包括测量控制NW和SPNC行为的参数，这将指导各自的原子和连续模型并验证其预测。这些纤锌矿纳米结构的掺杂、缺陷、去极化和温度在很大程度上未知的作用将在目标1-5中进行检查。重要性：SPNC被认为是下一代民用和军用应用的基石，其特点是传感，驱动和能量收集的适应性，多功能性和自主性。该研究将开创一种技术，以消除热电机械负载对压电系数的影响，克服单片压电陶瓷的众多局限性，开发高度通用的智能纳米复合材料，解决现有文献中的异常和不足，培训66名HQP，并促进技术转移到加拿大工业和军事。

***BACKGROUND: The aims of my newly proposed research program are to generate new knowledge to accurately model, characterise and develop the next generation of lightweight smart piezoelectric nanocomposites (SPNCs) for use as sensors, actuators and energy harvesters, with greater understanding of the fundamental parameters that govern their electromechanical behaviour. The new SPNCs are fabricated using preferentially aligned array of nanowires (NWs) with finite interspacing and encased by nanoscopic surface electrodes in an epoxy matrix. Due to their outstanding electromechanical properties, Zinc Oxide and Gallium Nitride NWs are selected. The piezoelectric coefficients define the electromechanical behaviour of NWs and SPNCs; beyond the small field condition, these coefficients are temperature dependent. ******RESEARCH PROGRAM: The long-term aims are to generate new knowledge leading to new SPNCs' designs and analysis tools, requiring the following short term objectives:***1. Determine the effective mechanical properties and the direct piezoelectric coefficients of a homogenised sensor fiber for the direct piezoelectric effect by applying mechanical strain at constant electric field using novel hybrid molecular dynamics (MD)-density functional theory (DFT) to a NW surrounded by an epoxy matrix. ***2. Compute the effective mechanical properties and the converse piezoelectric coefficients of a homogenised actuator fiber for the converse piezoelectric effect using DFT-MD. ***3. Determine the bulk electromechanical properties of SPNCs by scaling up a network of the effective sensor fibers developed in Objective 1 using 3D hierarchical multiscale strategy. ***4. Compute the bulk electromechanical properties of SPNC by scaling up a network of the effective actuator fibers developed in Objective 2 using modified micromechanics and homogenization schemes and a new network recognition strategy. ***5. Conduct extensive experimental work that involves the measurements of the parameters that govern the behaviour of NWs and SPNCs, which will guide the respective atomistic and continuum models and validate their predictions. The largely unknown role of doping, defects, depolarisation and temperature of these wurtzite nanostructures will be examined in Objectives 1-5.******SIGNIFICANCE: SPNCs are envisioned to be the building blocks of next generation civil and military applications, characterised by adaptability, multifunctionality and autonomy for sensing, actuating, and energy harvesting. The research will pioneer a technique to characterise the effect of thermo-electro-mechanical loading on the piezoelectric coefficients, overcome the numerous limitations of monolithic piezoceramics, develop highly versatile smart nanocomposites, address anomalies and deficiencies in existing literature, train 66 HQP, and facilitate technology transfer to Canadian industry and military.