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和图案化可以在单独的刚性和刚性材料中引起显著的变形特性。这利用了一个看起来很简单--尽管很难实现--的原理：结构是变形的，而不是坚硬的材料。界面显示出与主体材料显著不同的特性。例如，考虑界面在材料的耐腐蚀性和耐磨性中所起的作用，或者它们对材料的导电性和导热性的影响。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，在本项目中考虑的结构中实现了大变形能力。只有在全面了解相关力学原理的情况下，才能充分利用这些结构，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化可用的功能材料，即优化应力和位移的空间分布，以及在各种加载情况下提高寿命。因此，该项目的目标是对具有结构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，可以阐明潜在的力学(以及后来的热和电)机制，从而为开发具有大变形能力的结构多层复合材料奠定了理论基础。将利用连续介质力学模型和有限元分析来研究裂纹和分层的变形机制和破坏。将开发自动生成代表性体积元素的算法，以便于许多几何和材料属性的变化。分析了这些几何和材料参数对力学性能、变形能力、裂纹扩展和破坏行为的影响。从而为结构多层复合材料的开发和优化建立了理论数值框架。该项目将重点放在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，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.