Modelling the mechanical properties of interface structured multi-layer composites under large deformations

多层系统中的层和界面的结构化和图案化可以在单独的刚性和非柔性材料中引起显着的变形特性。这利用了一个看似简单但很难实现的原理：结构变形，而不是刚性材料。界面表现出的特性与块体材料的特性有很大不同。例如，考虑界面在耐腐蚀性和耐磨性中的作用或它们对材料中的电传导和热传导的影响。通过构造这些界面，不仅可以定制界面体积比，还可以引入额外的功能，例如本项目中考虑的结构所实现的大变形能力。只有全面了解所涉及的机械原理，才能实现充分利用这些结构，从而实现定制材料的开发和优化。在这方面需要解决的任务包括最大限度地利用可用的功能材料，即，优化应力和位移的空间分布，以及提高各种载荷情况下的使用寿命。因此，该项目的目标是对具有结构化界面的复合材料的结构-性能关系进行建模和研究。基于数值研究，基本的机械（和后来的热和电）机制可以阐明，从而形成的理论基础，能够大变形的结构化多层复合材料的发展。将采用连续介质力学模型和有限元分析来研究开裂和分层的变形机制和失效。将开发用于自动生成代表性体积元素的算法，以促进许多几何形状和材料特性的变化。将分析这些几何和材料参数对机械性能、变形能力、裂纹扩展和失效行为的影响。从而为结构化多层复合材料的开发和优化建立了理论数值框架。该项目将重点关注这些结构在微电子中的应用，但由于分析是基于几何力学关系，因此预计所获得的见解适用于各种材料类别和应用领域。

Structuring and patterning of layers and interfaces in multi-layer systems can induce remarkable deformation properties in individually stiff and inflexible materials. This utilises an apparently simple – however difficult to achieve – principle: The structure is deformed not the stiff material.Interfaces exhibit properties that can significantly vary from those of the bulk material. Consider for example the role interfaces play in corrosion and wear resistance or their influence on electrical and thermal conduction in a material. By structuring these interfaces not only the interface to volume ratio can be tailored but also additional functionality can be induced, for instance the large deformation capabilities achieved in the structures considered in this project.Utilising such structures to their full capability can only be achieved with a comprehensive understanding of the involved mechanical principles that will allow tailored material development and optimisation. Tasks that need to be tackled in this context include maximisation of available functional material, i.e., optimisation of the spatial distributions of stress and displacement, as well as improving life time under a variety of loading cases.The goal of this project therefore is modelling and investigation of structure-property relationships in composite materials with structured interfaces. Based on numerical studies, the underlying mechanical (and later thermal and electrical) mechanisms can be elucidated, thus, forming the theoretical basis for development of structured multilayer composites capable of large deformations. Continuum mechanical modelling and finite element analysis will be employed to study deformation mechanisms and failure by cracking and delamination. Algorithms for automatised generation of representative volume elements will be developed which facilitate variation of numerous geometry and material properties. The influence of these geometrical and material parameters on the mechanical properties, the deformation capabilities, crack propagation and failure behaviour will be analysed. Thereby building a theoretical numerical framework for the development and optimisation of structured multi-layer composites. The project will focus on application of these structures in micro electronics but as the analysis is based on geometry-mechanics relationships, it is expected that gained insights are applicable to a variety of material classes and application fields.