Multi-scale modeling of fracture behavior of polycrystalline ferroelectric ceramics under monotonic and cyclic electromechanical loading

单调和循环机电载荷下多晶铁电陶瓷断裂行为的多尺度建模

基本信息

批准号：
327013632
负责人：
Professor Dr. Meinhard Kuna
金额：
--
依托单位：
Institut für Mechanik und Fluiddynamik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/327013632?language=en
关键词：
Multi scale modeling fracture behavior

项目摘要

Nowadays, functional ferroelectric ceramics are widespread applied in engineering as sensors, actuators, or integrated component of smart composites, where they are exposed to coupled electrical and mechanical in-service loads. Because of their brittleness, cracks can be formed and propagate at material defects and local stress concentrations, which impairs the strength, life time and reliability of such devices. This project is aiming at investigating the fracture processes in ferroelectric materials and devices under electrical, mechanical and combined loading. The loading may happen monotonic or cyclic, which leads either to brittle fracture or to fatigue damage. A multi-scale approach is developed to model the material behavior of polycrystalline ferroelectric ceramics, which comprises the domain processes on the micro-scale and the non-linear electromechanical continuum laws on the macro-scale. These models are implemented in a finite element method. Cyclic electromechanical cohesive zone elements are used to simulate failure phenomena like damage, crack formation and crack growth.By means of these models, the electromechanical stress situation at cracks is investigated in order to find suitable fracture mechanical parameters and failure criteria. At the macro-scale, the configurational force concept is favored. At the micro-scale, the discrete microstructure of the polycrystal is reproduced to model the fracture process zone. This approach allows to correlate the properties of the process zone with the macroscopically measureable fracture toughness and crack parameters. The focus lies on the influence of the electric field on the loading situation and fracture toughness.As a result of the project, a simulation tool will be developed, which enables a scale-bridging quantitative description of the elementary failure processes, crack initiation and crack propagation of ferroelectric ceramics.Finally, the elaborated models are verified by comparison with available fracture experiments. They are exemplarily applied to selected ferroelectric devices such as multi-layer stack actuators or macro-fiber-composites.

如今，功能性铁电陶瓷广泛应用于智能复合材料的传感器，执行器或集成组件，并将其暴露于耦合的电气和机械服务载荷。由于它们的脆弱性，可以在物质缺陷和局部应力浓度下形成裂缝，并损害此类设备的强度，寿命和可靠性。该项目旨在研究电电，机械和组合负荷下的铁电材料和设备中的断裂过程。负载可能会发生单调或循环，这会导致脆性骨折或疲劳损伤。开发了一种多尺度方法来对多晶铁电陶瓷的材料行为进行建模，该陶瓷包括微尺度上的域过程和宏观尺度上的非线性机电连续性定律。这些模型以有限元方法实现。环状机电凝聚区元素用于模拟故障现象，例如损害，裂纹形成和裂纹生长。通过这些模型，研究了裂缝处的机电应力状况，以找到合适的断裂机械参数和故障标准。在宏观尺度上，偏爱配置力概念。在微尺度上，复制多晶的离散微观结构以建模断裂过程区域。这种方法允许将过程区域的性质与宏观可测量的断裂韧性和裂纹参数相关联。重点在于电场对负载情况和断裂韧性的影响。由于该项目的结果，将开发一个模拟工具，该工具可以对基本故障过程进行规模桥梁的定量描述，裂纹启动和铁电陶瓷的裂纹传播。通过与可用的Fracture实验相比，通过相比进行了详细的模型。它们被示例应用于选定的铁电设备，例如多层堆栈执行器或宏观纤维复合材料。