Production and characterization of complex folded cellular structures made of sheet metal

通过折叠平坦的半成品，可以产生三维的细胞结构。折叠结构可用于各种技术领域，特别是作为两个覆盖层之间的夹芯材料。夹层施工方法提供了将刚性、大面积构件投入使用的可能性。与传统的单片或差分构造方法相比，这些组件具有相当大的重量和材料节省。今天的细胞折叠结构只能由非常小的薄片厚度（50≤0.2 mm）的初始材料生产。除了用作夹层元件外，具有较厚金属板的折叠结构在工业用途中作为包层元件，碰撞和承载结构提供了相当大的潜力。由金属薄板制成的蜂窝状折叠芯基于等距折叠结构。在初始状态下，通过围绕一个或多个弯曲轴方向（BAO）的局部弯曲加工，将一个基本平坦的半成品形成重复的单元格。根据DIN 8582进行弯曲具有特殊的位置，因为局部弯曲轴的形成可以对工件（此处为核心）进行复杂的成型，从而可以实现非凡的应用和特定于应用的组件设计。该研究项目的目的是生产和表征由厚度大于0.5mm的铝或钢板制成的复杂细胞结构。为此，正在制定一个工作流程，涵盖从几何和结构设计到新开发的生产技术及其技术限制，再到在上述厚度范围内由金属板制成的优化结构的制造和检查/质量保证的所有方面。具体涉及以下子目标：——开发和转让的分析设计方法对折叠厚表- pre-structuring钣金的方法的发展过程开发生产折叠三明治的核心——造型三明治板的力学性能和过程的定义boundariesThe科学发现的这个项目一方面使折叠结构的更精确的评估潜在的由金属板作为一种新型的二维的核心材料另一方面，三明治的应用扩展了在复杂的、以前未完成的等距成形过程中金属板的行为和加工的基本知识。

By folding flat semi-finished products, three-dimensional cellular structures can be produced. Folding structures can be used in various technical fields, especially as sandwich core material between two covering sheets. Sandwich construction methods offer the possibility to put rigid, large-area components into effect. These components have considerable weight and material savings compared to conventional monolithic or differential construction methods.Today’s cellular folding structures can only be produced from initial materials with very small sheet thicknesses (s0 ≤ 0.2 mm). In addition to their use as sandwich elements, folded structures with thicker sheet metals offer considerable potential for the industrial use as cladding elements, crash and carrying structures.The cellular folding cores made of sheet metal are based on isometric folded structures. In the initial state, a mostly flat semi-finished product is formed into repeating unit cells by local bending processes around one or more bending axis orientations (BAO). Bending according to DIN 8582 takes an exceptional position, since the formation of local bending axes enables complex shaping of the workpiece (here the core), which enables an extraordinarily application and application-specific component design. The aim of the research project is the production and characterization of complex cellular structures made of aluminium or steel sheet with thicknesses greater than 0.5mm. For this purpose, a workflow is being developed that covers all aspects from the geometric and structural design to the newly developed production technologies and their technological limits to the manufacture and inspection / quality assurance of optimized structures made of sheet metal in the above-mentioned thickness range. The following sub-targets are addressed in particular: - Development and transfer of analytical design methods for folding thicker sheets - Development of methods for pre-structuring sheet metal - Process development for the production of folded sandwich cores - Modelling of the mechanical properties of sandwich panels and definition of process boundariesThe scientific findings of this project on the one hand enable a more precise estimation of the potential of folded structures made of sheet metal as a new type of core material for two-dimensional sandwich applications and on the other hand extend the basic knowledge on the behaviour and processing of sheet metal in complex, previously unfinished isometric forming processes.