A Methodical approach for additively manufactured heat-generating structures – linkage between material development, manufacturing process and geometry

材料挤出（MEX）等增材制造由于其逐层材料沉积的原理，提供了新的设计自由度。除其他优点外，这允许在一个部件内组合多种材料，而不需要额外的组装和连接过程。因此，能够实现材料特定功能的集成，如用于发热的导电性，这提供了高成本功能聚合物的非常有效的开发。发热结构的集成允许通过使用热激活的形状记忆聚合物来制造个性化的焦耳加热系统（几何形状和表面温度）或致动器。目前有两个主要挑战限制了这些潜力的开发。一个是功能复合材料在导电性方面的非常有限的性能，伴随着在加工温度下极高的粘度。另一个挑战是缺乏对工艺参数和几何形状的选择与所产生的电气部件特性之间的内在依赖关系的深入了解。这是由于制造过程中产生的各向异性引起的材料特性变化。由此可见，目前在材料开发、制造工艺和几何形状等方面对增材制造发热结构的系统设计还存在很大的局限性。本研究项目旨在为增材制造发热结构的设计开发一种方法论途径。工艺工程和工程设计领域之间的密切合作是阐明材料系统、工艺参数和几何设计之间复杂相互作用的先决条件。这包括研究功能聚合物的生产工艺，这些聚合物具有针对MEX的特定电气和工艺相关特性，以及用于达到特定表面温度的工艺和几何相关杠杆。通过线料级解析热像分析，对所有影响因素的影响进行评估，并考虑提供设计知识。将利用材料特性、制造工艺和几何定义之间的明确依赖关系来建立模型，该模型在最大程度上是基于物理的。它也适用于参数化的数值模型的有限元方法（FEM）。方法学方法和有限元模型的评估将通过具有初步定义的属性（表面温度和几何形状）的集成发热结构的有针对性的设计和制造来完成。

Additive Manufacturing like Material Extrusion (MEX), offers new freedom in design, due to its principle of layer-by-layer material deposition. Among other benefits, this allows a combination of multiple materials within one part, without additional assembly and joining processes are needed. Thus, an integration of material-specific functions as electrical conductivity for heat generation is enabled which provides a very efficient exploitation of high-cost functional polymers.The integration of heat-generating structures allows manufacturing individualized Joule heating systems (geometry and surface temperature) or actuators by using thermally activated shape-memory polymers. Two central challenges currently limit the exploitation of such potentials. One is the very limited performance of functional composites in terms of electrical conductivity accompanied by an extremely high viscosity at process temperature. The other challenge is the lacking in-depth knowledge about the inherent dependencies between the choice of process parameters and geometry and the resulting electrical part properties. This is due to a change in the material properties caused by anisotropies that originates from the manufacturing process. From this follows, that a systematic design of additively manufactured structures for heat generation with respect to aspects regarding material development, manufacturing process and geometry is strongly limited at present.This research project aims to develop a methodological approach for the design of additively manufactured heat-generating structures. The closely linked cooperation between the fields of process engineering and engineering design is the prerequisite for elucidating the complex interactions of the material system, process parameters and the design of geometry. This includes investigating the production process of functional polymers with defined electrical and process-relevant properties for MEX, as well as process and geometry related levers for reaching defined surface temperatures. By means of strand-level resolved thermographic analysis, the effect of all influencing factors is assessed and regarded for the provision of design-knowledge. The clarified dependencies between material properties, manufacturing process and geometry definition will be employed to establish a model, which is physically based to the greatest extend. It is also applied to parameterize a numerical model by means of the Finite Element Method (FEM). The evaluation of the methodological approach and the FEM-Model will be done by the targeted design and manufacturing of integrated heat-generating structures with preliminarily defined properties (surface temperature and geometry).