SLM-Topo: Development of a process specific topology optimization method for additive manufacturing of lightweight structures examplified by the SLM process

接近最终几何形状的生成制造是复杂部件生产技术的一个里程碑。选择性激光熔化（SLM）等方法是基于粉末的光束熔化工艺，在未来的工业应用中具有很高的潜力。然而，在这种情况下，附加值不能仅仅通过将这种生产技术应用于已经设计好的部件来产生。相反，可以通过利用所获得的设计自由来增强收益。此外，SLM受到工艺特定的限制，例如最小细节尺寸，悬垂角等，以及挑战，例如工艺管理，组件几何形状和最终材料属性之间的内在联系。这导致了在考虑几何和材料特性的情况下，要制造的部件的系统设计方面的研究空白。为了制定一个考虑到制造过程中几何约束和冶金缺陷的策略，必须针对SLM的传统设计准则开发一个新的设计概念。对于传统的拓扑优化，采用各向同性、均质材料模型，该模型预设了组件中相应的材料特性。在增材制造零件的情况下，材料性能是各向异性和不均匀分布在整个组件。在生成制造过程的背景下，计算的优化结果可以在SLM过程中产生，而无需其他必要的人工返工。因此，本研究项目的目的是开发一种拓扑优化方法，该方法特别考虑了材料的各向异性和非均匀性，以获得最适合增材制造工艺的部件几何形状。优化的目的是在考虑强度限制的情况下使构件刚度最大化。这使得增材制造技术领域的进一步轻量化设计潜力得以开发。将使用以材料轻量化设计而闻名的AlSi10Mg合金，该合金在SLM工艺中也可以进行出色的加工。因此，拓扑结构的优化扩展到由SLM工艺产生的材料性能，并最终在组件测试中得到验证。必要的研究工作将在卡尔斯鲁厄理工学院（KIT）的IPEK -产品工程研究所和卡尔斯鲁厄理工学院（KIT）的IAM-WK -应用材料研究所（IAM WK）之间合作进行，利用拓扑优化和材料表征领域的广泛知识。

The generative manufacturing close to the final geometries represents a milestone in the production technology of complex components. Methods such as selective laser melting (SLM) are powder-based beam melting processes, with high potential in future industrial use. In this case, however, the added value can not be generated solely by the application of this production technology to already designed components. Rather, the benefit can be enhanced by exploiting the design freedom gained. Furthermore, the SLM is subject to process-specific limitations, such as minimal detail size, overhang angle, etc., as well as challenges, such as the inherent link between process management, component geometry and resulting material properties. This results in a research gap in the systematic design of components which are to be manufactured in addition, taking into account both geometrical and material-specific properties. In order to develop a strategy, which takes into account, both the geometrical constraints and metallurgical defects during the manufacturing process, a new design concept has to be developed towards conventional design guidelines for SLM.For conventional topology optimization, isotropic, homogeneous material models are used which presuppose corresponding material properties in the component. In the case of additive manufactured parts, the material properties are distributed anisotropically and inhomogeneously across the component. In the context of generative manufacturing processes there is considerable potential that the calculated optimization results can be produced in the SLM process without the otherwise necessary manual re-work. The aim of this research project is thus to develop a topology optimization method, which specifically takes into account anisotropic and inhomogeneous material properties in order to obtain a component geometry, which is optimally adapted to the additive manufacturing process. The aim of the optimization is the maximization of the component stiffness, taking into account strength restrictions. This allows further lightweight design potentials in the field of additive production technology to be developed. The alloy AlSi10Mg, which is known from the material lightweight design and can also be processed excellently in the SLM process, will be used. The optimization of the topology is thereby extended to the material properties as resulting from the SLM process, and finally validated in component tests. The necessary research work will be carried out in cooperation between the IPEK – Institute for Product Engineering at the Karlsruhe Institute of Technology (KIT) and the IAM-WK – Institute for Applied Materials - IAM WK at the Karlsruhe Institute of Technology (KIT), using the extensive knowledge in the areas of topology optimization and material characterization.