Lattice cores for high performance sandwich composite structures

夹层板广泛应用于工程应用，特别是在航空航天和汽车领域，当结构质量是一个关键的性能指标时，夹层板可以取代传统的大块材料。值得注意的是，蜂窝芯为夹层板提供了独特的性能组合，包括高比刚度和高比强度，以及低导热性，这使它们成为承载，隔热和吸能功能的理想选择。核心的机械性能在很大程度上取决于变形“模式”，即细胞壁的弯曲与拉伸。在相同的相对密度下，细胞壁发生轴向拉伸的岩心比主要通过细胞壁弯曲或屈曲变形的岩心坚硬十倍。这个博士项目的目的是研究通过在核心单元细胞中引入多材料关节和弯曲铰链，在晶格中诱导拉伸主导行为的可行性。该项目将提供一种新颖而灵活的方法来定制特定的刚度、强度和热性能，而不仅仅是通过单独作用于单元胞的拓扑结构来实现。这些新型核心的特性将通过高保真有限元分析和实验来探索，并采用增材制造方法来构建原型。该项目的主要目标是：-开发高保真有限元模型，以了解单元格和组件级别的晶格核的弹性，非弹性和热响应。-优化拓扑结构和多材料铰接结构，通过参数化建模实现性能最大化。-优化格芯的增材制造初始原型。-以有效和稳健的方式评估可制造性。-测试原型结构，并根据有限元分析模拟评估结果。

Sandwich panels are employed in a wide range of engineering applications, especially in the aerospace and automotive sectors, to replace traditional bulk materials whenever structural mass is a critical performance metric. Notably, cellular cores provide a unique combination of properties to sandwich panels, including high specific stiffness and high specific strength, as well as low thermal conductivity, which makes them ideal for load-bearing, thermal insulation and energy-absorbing functions. The mechanical performance of the core strongly depends on the deformation "mode", i.e. bending versus stretching, of the cell walls. Cores with cell walls undergoing axial stretching can be ten times stiffer than those deforming primarily through wall bending or buckling for the same relative density. The aim of this PhD project is to investigate the feasibility of inducing stretch-dominated behaviour in lattices via the introduction of multi-material joints and flexural hinges in the core unit cell. This project will provide a novel and flexible method for tailoring specific stiffness, strength and thermal properties beyond what can be achieved by acting upon the topology of the unit cell alone. The properties of these novel cores will be explored both numerically, via high-fidelity finite element analysis, and experimentally, employing additive manufacturing methods to build prototypes. The key objectives of this project are: - Development of high-fidelity finite element models to understand the elastic, inelastic and thermal response of lattice cores at the unit cell and assembly levels. - Optimisation of topology and multi-material hinged configurations to maximise the performance through parametric modelling. - Additive manufacturing initial prototypes of the optimised lattice cores. - Assessing the manufacturability in an efficient and robust fashion. - Testing the prototype structures and evaluate the results against the finite element analysis simulations.