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，表征和开发下一代轻质智能压电纳米复合材料（SPNCs），用于传感器，致动器和能量收集器，更深入地了解控制其机电行为的基本参数。新型spnc采用有限间距优先排列的纳米线阵列（NWs），并在环氧树脂基体中包裹纳米级表面电极。由于氧化锌和氮化镓具有出色的机电性能，因此选择了NWs。压电系数定义了NWs和spnc的机电特性；除了小场条件外，这些系数与温度有关。******研究计划：长期目标是产生导致新的spnc设计和分析工具的新知识，需要以下短期目标：利用新型混合分子动力学(MD)-密度泛函理论（DFT）对环氧基包围的NW施加恒定电场下的机械应变，确定均质传感器光纤的有效力学性能和直接压电系数。* * * 2。利用DFT-MD计算了均匀化致动器纤维的有效力学性能和逆压电系数。* * * 3。通过使用3D分层多尺度策略扩大目标1中开发的有效传感器光纤网络，确定spnc的整体机电特性。* * * 4。通过使用改进的微力学和均质化方案以及新的网络识别策略，扩大目标2中开发的有效致动器纤维网络，计算SPNC的整体机电性能。* * * 5。开展广泛的实验工作，包括测量控制NWs和spnc行为的参数，这将指导各自的原子和连续体模型并验证其预测。这些纤锌矿纳米结构的掺杂、缺陷、去极化和温度的未知作用将在目标1-5中进行研究。******意义：spnc被设想为下一代民用和军事应用的基石，其特点是适应性、多功能性和自主的传感、驱动和能量收集。该研究将开拓一种技术，以表征热电机械载荷对压电系数的影响，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缺陷，培训66 HQP，并促进技术向加拿大工业和军事转移。

***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.